1.29 JAKE BRAKE®
SERIES 60 SERVICE MANUAL
1.29 JAKE BRAKE®
The engine brake has been designed to fit on the Series 60 engine with no additional valve cover
spacers. There are three styles of valve covers for the Series 60 engine. On engines equipped
with a two-piece aluminum valve cover, it is NOT necessary to remove the lower valve cover to
install the engine brake. However, one style of upper valve cover may require modification at the
breather housing location (inside) for engine brake clearance.
The model, part number and serial number are located on the nameplates at the top of each
housing. See Figure 1-425.
1. Identification Plate
Figure 1-425
Nameplate Location on Housing
NOTICE:
Only the specific brake model can be used with the engine model
it was designed for. Also, the correct slave piston adjustment
specification must be used. Failure to follow these instructions
may result in serious engine or engine brake damage.
Listed in Table 1-9 are the different Jake Brake® models used and the slave piston adjustment
specification.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-533
JAKE BRAKE®
1.29
Model Number
Model Year
Engine
Displacement
Engine
Brake
Slave Piston
Adjustment
6067WU40
Pre-1991
11.1L
760/760A
0.660 mm (0.026 in.)
6067GU40
Pre-1991
12.7L
760/760A
0.508 mm (0.020 in.)
6067WU60
1991
11.1L
760/760A
0.660 mm (0.026 in.)
6067GU40
1991
12.7L
765
0.660 mm (0.026 in.)
6067GU28
1991
12.7L
765
0.660 mm (0.026 in.)
6067GU91
1991
12.7L
765
0.660 mm (0.026 in.)
6067WK60
1994
11.1L
760A
0.660 mm (0.026 in.)
6067GK60
1994
12.7L
765
0.660 mm (0.026 in.)
6067GK28
1994
12.7L
765
0.660 mm (0.026 in.)
6067EK60
1998
11.1L
760B
0.584 mm (0.023 in.)
6067PK60
1998
12.7L
765A
0.584 mm (0.023 in.)
6067TK60
1998
12.7L
765A
0.584 mm (0.023 in.)
6067TK45
1998
12.7L
765A
0.584 mm (0.023 in.)
6067MK60
1998
12.7L
770
0.584 mm (0.023 in.)
6067BK60
1998
12.7L
770
0.584 mm (0.023 in.)
6067HKXX
1998 (Non-Line Haul)
14L
770
0.584 mm (0.023 in.)
6067MK28, 6067MK45,
6067MK57, 6067MK60
2000
12.7L Standard
790
0.660 mm (0.026 in.)
6067BK28, 6067BK45,
6067BK57, 6067BK60
2000
12.7L Premium
790
0.660 mm (0.026 in.)
6067HK45, 6067HK60
2000
14L U.S.
790A
0.660 mm (0.026 in.)
6067WK28, 6067WK60
2000
11.1L
790B
0.660 mm (0.026 in.)
6067LK28, 6067LK45,
6067LK60
2000
11.1L
790B
0.660 mm (0.026 in.)
6063GK60, 6067GK28,
6067GK45, 6067GK91,
6067PK62, 6067TK28,
6067TK60, 6067TK62
2000
12.7L
790B
0.660 mm (0.026 in.)
6067HK62
2000
14L Australian
790C
0.660 mm (0.026 in.)
6067MK28, 6067MK45,
6067MK57, 6067MK60
2000
12.7L Standard
795
0.813 mm (0.032 in.)
6067BK28, 6067BK45,
6067BK57, 6067BK60
2000
12.7L Premium
795
0.813 mm (0.032 in.)
6067HK45, 6067HK60
2000
14L U.S.
795
0.813 mm (0.032 in.)
6067WK28, 6067WK60
2000
11.1L
795
0.813 mm (0.032 in.)
6067LK28, 6067LK45,
6067LK60
2000
11.1L
795
0.813 mm (0.032 in.)
All information subject to change without notice.
1-534
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
6063GK60, 6067GK28,
6067GK45, 6067GK91,
6067PK62, 6067TK28,
6067TK60, 6067TK62
2000
12.7L
795
0.813 mm (0.032 in.)
6067HK62
2000
14L Australian
795
0.813 mm (0.032 in.)
All slave piston adjustments shown here are current as of the date of this manual and supersede all previous adjustments.
XXXX = Model numbers to be determined.
Table 1-9
Jake Brake® Model Information
NOTE:
All engines built after serial number 06R0004455 have the correct engine parts for
engine brake installation. The model numbers have changed because of design changes
in the engine brakes.
NOTE:
All Series 60 engines with serial numbers 06R0004455 or higher are Jake Brake® ready.
Do not install a Jake Brake® on engines with lower serial numbers.
Effective August 10, 2000, Model 795 Jake Brakes are used on all Series 60 engines requiring
an engine brake.
Former Jake Brake® production models for the Series 60 engine were the 760A (which replaced
model 760), 760B, 765, 765A, 770 and 790.
Detroit Diesel engine model Nos. 6067GU28 and 6067GK28 are for bus/coach applications.
Due to interference fits on some coach chassis, a two-housing Jake Brake® kit may be required.
Contact your Detroit Diesel Distributor for information on these kits.
Jake Brake® is a registered trademark of Jacobs Vehicle Systems. J-Lash™ is a trademark of Jacobs Vehicle Systems.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-535
1.29
JAKE BRAKE®
Energizing the engine brake effectively converts a power-producing diesel engine into a
power-absorbing air compressor. This is accomplished through motion transfer using a
master-slave piston arrangement which opens cylinder exhaust valves near the top of the normal
compression stroke, releasing the compressed cylinder charge to exhaust. See Figure 1-426.
1. Exhaust Valve
7. Oil In
2. Slave Piston Assembly
8. Check Valve (Model 760)
3. Exhaust Valve
9. Solenoid Valve
4. Leveling Screw
10. Control Valve
5. Slave Piston Adjusting Screw
11. Master Piston
6. Accumulator
12. Injector Pin and Roller
Figure 1-426
Jake Brake® Schematic
All information subject to change without notice.
1-536
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
The blowdown of compressed air to atmospheric pressure prevents the return of energy to the
engine piston on the expansion stroke, the effect being a net energy loss, since the work done in
compressing the cylinder charge is not returned during the expansion process.
Exhaust blowdown occurs as the energized solenoid valve permits engine lube oil to flow under
pressure through the control valve to both the master piston and the slave piston. See Figure 1-426.
Oil pressure causes the master piston to move down, coming to rest on the injector rocker arm
roller.
The injector rocker arm begins its travel as in the normal injection cycle, moving the master piston
upward and directing high-pressure oil to the slave piston. The ball check valve in the control
valve traps high-pressure oil in the master-slave piston system.
High pressure oil causes the slave piston to move down, momentarily opening the exhaust valves,
while the engine piston is near its top-dead-center position, releasing compressed cylinder air to
the exhaust manifold.
At the bottom of its stroke, the slave piston separates from the valve in the slave piston adjusting
screw, allowing high pressure oil to flow into the accumulator. This reduces the pressure in the
high pressure circuit, permitting the slave piston to retract and the exhaust valves to close in
preparation for the normal exhaust valve cycle. The oil pressure reserved in the accumulator
ensures that the hydraulic circuit is fully charged for the next cycle. Compressed air escapes to the
atmosphere, completing a compression braking cycle.
The Jake Brake® is electronically controlled. Jake Brake® control system wiring will
vary depending on the vehicle manufacturer. For a general overview of the Jake Brake®,
see Figure 1-427 and see Figure 1-428.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-537
1.29
JAKE BRAKE®
1. Ball Check Valve (Model 760 Only)
12. Solenoid Valve
2. Washer
13. Seal Rings
3. Master Piston
14. Accumulator Piston
4. Master Piston Spring
15. Power Lash Assembly
5. Washer and Screw Assembly
16. Slave Piston Adjusting Screw
6. Control Valve
17. Slave Piston
7. Collar
18. Slave Piston Leveling Screw
8. Control Valve Spring
19. Bridge
9. Collar Spring
20. Return Spring
10. Washer
21. Screw
11. Snap Ring Retainer
Figure 1-427
Typical Model 760, 765, or 770 Jake Brake® Assembly
All information subject to change without notice.
1-538
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1. Solenoid Valve
13. Control Valve Cover
2. Solenoid Upper Seal Ring
14. Retaining Ring
3. Solenoid Center Seal Ring
15. Adjusting Screw*
4. Solenoid Lower Seal Ring
16. Locknut
5. Master Piston
17. Slave Piston
6. Master Piston Pushrod
18. Slave Piston Bridge
7. Master Piston Spring
19. Outer Slave Piston Spring
8. Master Piston Retainer
20. Inner Slave Piston Spring
9. Master Piston Retaining Ring
21. Spacer Tube
10. Control Valve
22. Shoulder Bolt
11. Outer Control Valve Spring
23. Drive Screw
12. Inner Control Valve Spring
24. Wire Harness Clip
*Note that Model 790 Jake Brake® uses a J-Lash™ assembly. Model 795 Jake Brake® uses a solid screw.
Figure 1-428
Typical Model 790/795 Jake Brake® Assembly
NOTICE:
This application and adjustment information must be strictly
followed. Failure to follow these instructions may result in
serious engine or engine brake damage.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-539
1.29
JAKE BRAKE®
1.29.1
Repair or Replacement of Jake Brake®
To determine if repair is possible or replacement is necessary, perform the following procedure.
See Figure 1-429.
Figure 1-429
Jake Brake® Repair or Replacement Flowchart
All information subject to change without notice.
1-540
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1.29.2
Removal of Model 760, 765, or 770 Jake Brake®
Remove the model 760, 765, or 770 Jake Brake® as follows:
NOTE:
The following procedures apply to Model 760, 765, and 777 Jake Brake®. For Model
790/795 Jake Brake® removal procedures, refer to section 1.29.6.
To avoid injury, never remove any engine brake
component with engine running.
1. Disconnect starting power for engine. Refer to OEM guidelines.
2. Remove the engine rocker cover. Refer to section 1.6.2 for one-piece, refer to section 1.6.3
for two-piece and refer to section 1.6.5 for three-piece.
NOTE:
If the engine is equipped with an aluminum two-piece valve cover, remove only the upper
valve cover when installing the engine brake.
3. Note the location of the rocker arm shaft, the exhaust valve rocker arm, the fuel injector
rocker arm, and the intake valve rocker arm.
4. Disconnect the solenoid wiring harness connectors from the engine brake solenoids.
See Figure 1-430.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-541
1.29
JAKE BRAKE®
1. Cylinder Head
4. Washers (3 each)
2. Jake Brake® Assembly
5. Capscrews (3 each)
3. Solenoid
6. Engine Brake Harness
Figure 1-430
Jake Brake® Assembly
5. Remove the nine capscrews and washers that secure the engine brake assemblies to the
cylinder head. See Figure 1-430.
NOTE:
Only the Model 760 Jake Brake® uses two different length capscrews. Six bolts, 120 mm
(4.72 in.) long, are used on the exhaust side of the engine. Three bolts, 110 mm (4.33
in.) long, are used on the intake side of the engine. These bolts must be reinstalled
in their correct positions.
6. Remove the engine brake assemblies and the spacer bar.
All information subject to change without notice.
1-542
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
Disassembly of Model 760, 765, or 770 Jake Brake®
1.29.3
Remove the control valve as follows:
To avoid injury from flying parts when working with
components under spring tension, wear adequate eye
protection (face shield or safety goggles).
1. Press down on control valve washer using an appropriate diameter rod to relieve spring
pressure. See Figure 1-431.
1. Jake Brake® Assembly
3. Snap Ring Retainer
2. Spring
4. Snap Ring Pliers
Figure 1-431
Relieving Spring Pressure
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-543
1.29
JAKE BRAKE®
2. Using retaining ring pliers, remove retaining ring.
3. Slowly remove cover until spring pressure ceases, then remove the two control valve
springs and collar. See Figure 1-432.
1. Jake Brake® Assembly
5. Washer
2. Control Valve
6. Collar Spring
3. Collar
7. Control Valve Spring
4. Snap Ring Retainer
Figure 1-432
Removing Control Valve Springs and Collar
4. Using needle-nose pliers, reach into the bore and grasp the stem of the control valve.
Remove control valve.
All information subject to change without notice.
1-544
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
Remove the slave piston adjusting screw as follows:
1. Loosen slave piston adjusting screw locknut.
2. Remove adjusting screw from housing. See Figure 1-433.
1. Jake Brake® Assembly
Figure 1-433
2. Slave Piston Adjusting Screw
Removing Slave Piston Adjusting Screw
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-545
1.29
JAKE BRAKE®
Remove the solenoid valve as follows:
NOTICE:
To avoid possible engine damage, do not disassemble
or tamper with the solenoid valve.
1. Disconnect solenoid valve harness.
2. Using a 7/8 in. socket and extension for former solenoids or a 3/4 in., 6 point socket and
extension for current solenoids, unscrew solenoid valve.
3. Remove and discard the three rubber seal rings. See Figure 1-434.
1. Seal Rings (3)
Figure 1-434
2. Solenoid
Removing Rubber Seal Rings
4. If the lower ring stays in the bottom of the housing bore, remove with a piece of wire.
All information subject to change without notice.
1-546
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
Remove the accumulator as follows:
To avoid injury from flying parts when working with
components under spring tension, wear adequate eye
protection (face shield or safety goggles).
1. Push down on the accumulator cover using the appropriate diameter rod, and remove the
retaining ring. See Figure 1-435.
1. Jake Brake® Assembly
3. Retaining Ring Pliers
2. Retaining Ring
Figure 1-435
Removing Retaining Ring
2. Relieve pressure on the accumulator cover.
3. Remove the cover and spring.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-547
1.29
JAKE BRAKE®
4. Use a magnet to remove the piston from the accumulator bore. See Figure 1-436.
1. Jake Brake® Assembly
4. Retaining Ring
2. Piston
5. Washer
3. Spring
Figure 1-436
Removing Piston from Accumulator Bore with Magnet
All information subject to change without notice.
1-548
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
Remove the master piston as follows:
1. Remove the screw, washer, and master piston spring from the housing.
2. Remove the master piston. See Figure 1-437.
NOTE:
Use needle-nose pliers, if necessary.
1. Washer and Screw Assembly
3. Master Piston
2. Jake Brake® Assembly
4. Master Piston Spring
Figure 1-437
Removing the Master Piston
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-549
1.29
JAKE BRAKE®
On Model 760 only, remove the ball check valve as follows:
1. Remove the plug.
2. Remove the ball check valve and spring.
Remove the slave piston as follows:
1. Remove the screw and washer that retains the slave piston return spring.
2. Remove the bridge and the slave piston. See Figure 1-438.
1. Slave Piston Bridge
4. Return Spring
2. Jake Brake® Housing
5. Washer
3. Slave Piston
6. Screw
Figure 1-438
Removing Bridge and Slave Piston
All information subject to change without notice.
1-550
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
3. Loosen the leveling screw locknut and remove the leveling screw from the bridge.
See Figure 1-439.
1. Slave Piston Bridge
Figure 1-439
2. Slave Piston Leveling Screw
Removing the Leveling Screw from the Bridge
The injector rocker arm contains a pin and roller for actuating the engine brake master
piston. If excessive wear or damage to the roller is present, replace the rocker arm assembly.
Refer to section 1.6.2 .
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-551
1.29
JAKE BRAKE®
1.29.3.1
Cleaning of Model 760, 765, or 770 Jake Brake®
Clean the Jake Brake® as follows:
NOTE:
Use an OSHA-approved cleaning solvent when washing parts. Be sure to coat parts with
clean engine oil when reinstalling them.
1. Wash the control valves with approved cleaning solvent.
2. Push a wire through the hole in the base of the valve to the distance required to ensure
that the ball check is free.
NOTE:
The ball should lift with light pressure on the wire.
To avoid injury from flying debris when using compressed air,
wear adequate eye protection (face shield or safety goggles)
and do not exceed 40 psi (276 kPa) air pressure.
3. Dry the valve with compressed air, and wipe clean with a paper towel.
4. Thoroughly clean the control valve bore in the housing using clean paper towels.
5. Clean slave piston adjusting screw in an approved cleaning solvent.
6. Clean out the solenoid valve bore in the housing.
NOTICE:
Use clean paper towels to clean the solenoid valve bore. Never
use rags, as they may leave lint and residue which can plug the
oil passageways, causing Jake Brake® malfunction.
7. Clean the master piston in approved cleaning solvent.
All information subject to change without notice.
1-552
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1.29.3.2
Inspection of Model 760, 765, or 770 Jake Brake®
The Jacobs engine brake is typically a trouble-free device. However, inspections are necessary
and some maintenance is required. Use the following procedures to keep the engine brake in top
condition.
Inspect the Jake Brake® as follows:
1. Inspect slave piston adjusting screw for protrusion, spring pressure and freedom of
movement.
NOTE:
The plunger should protrude from the bottom of the screw, have light spring pressure
apparent when depressed, and move freely. Be sure the retaining ring is fully engaged
in its groove (groove is located on the bottom of the reset screw and top of the
POWER-LASH assembly).
[a] If the plunger does not protrude, the spring does not have light pressure or does not
move freely, replace the entire screw assembly. Refer to section 1.29.4
[b]
If the slave piston adjusting screw meets specifications, continue with inspection.
2. Inspect the accumulator for wear or damage.
[a] If worn or damaged, replace the accumulator. Refer to section 1.29.4.
[b]
If accumulator is not worn or damaged, continue with inspection.
3. Inspect the master piston bore for wear or damage.
NOTE:
Some wear marks are permissible.
[a] If worn or damaged, replace the master piston. Refer to section 1.29.4.
[b]
If not worn or damaged, continue with inspection.
4. Apply clean lube oil to the piston, and insert into bore.
NOTE:
Master piston should move in and out freely with no binding.
[a] If binding occurs, replace master piston and/or housing. Refer to section 1.29.4.
[b]
If no binding occurs, continue with inspection.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-553
1.29
JAKE BRAKE®
5. Inspect master piston spring for relaxation.
NOTE:
The spring should hold the master piston completely in the housing.
[a] If relaxed, replace the spring. Refer to section 1.29.4.
[b]
If spring holds tightly, continue with inspection.
6. Inspect the ball check valve (Model 760 only) for wear or damage.
[a] If worn or damaged, replace ball check valve. Refer to section 1.29.4.
[b]
If not worn or damaged, proceed with inspection.
7. Inspect slave piston components for excessive wear or damage.
[a] If worn or damaged, replace slave piston component.
[b]
1.29.3.3
If not worn or damaged, proceed with inspection.
Inspection of Control Valve
Inspect the control valve as follows:
1. Dip the control valves in clean lube oil.
2. Holding the control valve by the stem, let it drop into the bore.
[a] If binding occurs or if the ball sticks in the valve, replace the control valve.
Refer to section 1.29.4.
[b]
If no binding occurs and the ball does not stick in the control valve, assemble the
Jake Brake®. Refer to section 1.29.4.
All information subject to change without notice.
1-554
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1.29.4
Assembly of Model 760, 765, or 770 Jake Brake®
Install the control valve as follows:
1. Slip the control valve into the bore. See Figure 1-440.
NOTE:
Make sure the control valve collar is installed with the longer sleeve area facing up. If the
collar is installed upside down, the engine brake cylinder will not operate.
1. Jake Brake® Assembly
5. Washer
2. Control Valve
6. Collar Spring
3. Collar
7. Control Valve Spring
4. Snap Ring Retainer
Figure 1-440
Installing the Control Valve
2. Install the control valve collar and two springs.
NOTE:
Ensure the collar is installed with the longer sleeve area facing up. If the collar is installed
upside down, the engine brake cylinder will not operate.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-555
1.29
JAKE BRAKE®
3. Press the cover (washer) into place.
4. While holding the cover tightly in place, install the retaining ring.
5. Rotate retaining ring ears 90 degrees to assure ring is seated in groove.
Install the slave piston adjusting screw as follows:
1. Place the screw in the housing. See Figure 1-441.
1. Jake Brake® Assembly
Figure 1-441
2. Slave Piston Adjusting Screw
Installing the Slave Piston Adjusting Screw
2. Torque the slave piston adjusting screw locknut to 35 N·m (25 lb·ft).
All information subject to change without notice.
1-556
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
Install the solenoid valve as follows:
NOTE:
As of October 19, 1997, former solenoids have been replaced with the current improved
solenoids. The current solenoids have an increased installation torque and improved
durability. The current solenoid is interchangeable with the former.
1. Coat new solenoid valve seal rings with clean lube oil.
NOTE:
Use current upper seals when installing current solenoids. New seals are identified
with yellow stripes.
2. Install the upper and center seal rings on the solenoid valve body and the lower seal ring
into the bottom of the bore in the housing. See Figure 1-442.
1. Seal Rings (3)
Figure 1-442
2. Solenoid
Installation of Solenoid Valve Seal Rings
3. Make sure the seals are seated properly.
4. Using a 7/8 in. socket and extension for former solenoids or a 3/4 in., 6 point socket
and extension for current solenoids, carefully screw the solenoid valve into the housing
without unseating the seals.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-557
1.29
JAKE BRAKE®
5. Torque the former solenoid to 12.4 N·m (9 lb·ft). Torque the current solenoid to 20 N·m
(15 lb·ft.)
NOTE:
Be careful not to twist the seals while installing.
Install the accumulator as follows:
1. Place the piston into the accumulator bore.
2. Insert the spring, and install the cover.
3. Push down the accumulator cover, and insert retaining ring.
Install the master piston as follows:
1. Apply clean lube oil to the piston.
2. Insert master piston into bore. See Figure 1-443.
1. Washer and Screw Assembly
2. Jake
Brake®
Assembly
Figure 1-443
3. Master Piston
4. Master Piston Spring
Inserting Master Piston into Bore
All information subject to change without notice.
1-558
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
3. Install spring, washer, and screw.
NOTE:
Make sure spring legs are centered around master piston boss.
4. Torque screw to 10 N·m (7.4 lb·ft).
On model 760 only, install the ball check valve as follows:
1. Install the ball check valve and spring. See Figure 1-444.
1. Ball Check Valve
3. Pipe Plug
2. Spring
Figure 1-444
Installation of Ball Check Valve
2. Insert the plug. Torque pipe plug to 11.2 N·m (8.3 lb·ft).
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-559
1.29
JAKE BRAKE®
Install the slave piston as follows:
1. Install the screw from the slave piston side of the bridge.
2. Install the leveling screw locknut.
3. Install the bridge with the leveling screw toward the center of the housing.
See Figure 1-445.
1. Washer
4. Bridge Assembly
2. Screw
5. Jake Brake® Housing
3. Torsion Spring
Figure 1-445
Installing Bridge with Leveling Screw Toward Center of Housing
All information subject to change without notice.
1-560
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
4. Install the slave piston assembly torsion spring with the ends over the bridge.
See Figure 1-446.
Figure 1-446
Installing the Slave Piston Assembly Torsion Spring
5. Install the screw and washer over the center part of the spring.
NOTICE:
While tightening the screw on the torsion spring, push the
spring toward the slave piston assembly. Failure to do so may
result in contact between the intake valve adjusting screw and
torsion spring. Serious engine damage may result.
6. Torque the screw to 20 N·m (15 lb·ft.).
7. Torque the slave piston leveling screw locknut to 47 N·m (35 lb·ft.).
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-561
1.29
JAKE BRAKE®
1.29.5
Installation of Model 760, 765, or 770 Jake Brake®
Install the model 760, 765, or 770 Jake Brake® as follows:
NOTE:
The following procedures apply to Model 760, 765, and 770 Jake Brake®. For Model
790/795 Jake Brake® installation procedures, refer to section 1.29.8.
1. Adjust the intake and exhaust valve clearances and set the injector heights.
Refer to section 12.2 .
To avoid injury from flying debris when using compressed air,
wear adequate eye protection (face shield or safety goggles)
and do not exceed 40 psi (276 kPa) air pressure.
2. Attach the length of tubing to a blow gun nozzle, and blow out the oil from the bolt holes.
3. Cover the holes with hand towels to minimize oil spray.
NOTE:
Removing the oil from the bolt holes prevents the cylinder head from cracking when
tightening the bolts.
All information subject to change without notice.
1-562
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
4. Place the spacer bar on the exhaust manifold side of the cylinder head with the "OUT"
markings adjoining each other and facing the exhaust manifold. See Figure 1-447, and
see Figure 1-448.
Figure 1-447
Spacer Bars with "Out" Marks Adjoined
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-563
1.29
JAKE BRAKE®
Figure 1-448
Location of Spacer Bars
5. Place the three engine brake housings over the rocker shafts with the solenoid valves
toward the camshaft side of the engine.
NOTE:
Be sure housings do not interfere with wiring harness.
All information subject to change without notice.
1-564
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
To avoid injury from loss of vehicle braking control due
to an improperly installed Jake Brake, do not mix rocker
arm shaft and Jake Brake mounting bolts.
NOTICE:
Do not mix the rocker arm shaft bolts and the Jake Brake®
capscrews. If the rocker arm shaft bolt is mistakenly used to
mount the Jake Brake® housing, the longer shoulder on the bolt
will block the oil supply to the Jake Brake® on the camshaft
side of the housing. The brake will not retard the engine as
designed. This condition could cause vehicle damage.
NOTE:
The rocker arm shaft capscrew and Jake Brake® capscrew, part of the Jake Brake®
assembly, are similar in appearance. Both are M12 x 110 mm (4.33 in.) long and have
12–point heads.
NOTE:
In the event of a housing hold down bolt failure on a Jacobs engine brake housing,
replace all bolts on that particular housing.
NOTICE:
Use bolts that have the Jacobs logo, circled "J". Installation
of bolts that do not have the circled "J" may result in damage
to the engine, engine brake or both.
[a] The Jake Brake® bolt has the Jacobs logo (circled "J") and the letters "EF" marked on
the head. The bolt length is no longer marked atop the bolt head.
[b]
The DDC rocker arm shaft bolt has the DDC logo (spinning arrows) and the vendor
I.D. (F-C) on its head.
[c] Jake Brake® model 760 requires two bolts along with one bolt and new washers.
NOTE:
Be sure that only Jake Brake® bolts, see Figure 1-449, are installed in the Jake Brake®
housing.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-565
1.29
JAKE BRAKE®
[d]
The DDC bolt shoulder is much longer, 17.0 mm (0.669 in.) versus 4 mm (0.157 in.)
than the Jake Brake® bolt. See Figure 1-449.
Figure 1-449
Jake Brake® and DDC Bolt Identification
All information subject to change without notice.
1-566
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
NOTICE:
The model 760 uses two lengths of capscrews. Six 120 mm bolts
should be installed on the exhaust side of the engine. Three
110 mm bolts should be installed on the camshaft side of the
engine. Failure to do so will result in engine damage.
6. On model 760, install one washer onto each 120 mm (4.75 in.) bolt, and insert into brake
housing on the exhaust manifold side (two per housing). See Figure 1-450.
1. Washer
Figure 1-450
2. Long Bolt
Installation of Jake Brake Housing Bolts on Exhaust Manifold
Side
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-567
1.29
JAKE BRAKE®
7. On model 760, install one washer on the 110 mm (4.375 in.) bolt, and insert into brake
housing at the camshaft side (one per housing). See Figure 1-451.
1. Jake Brake® Housing Assembly
Figure 1-451
2. Capscrew
Installation of Jake Brake® Housing Bolts on Camshaft Side
8. On models 760A, 760B, 765, and 765A, lubricate each hold down bolt with clean engine
oil.
NOTE:
All the housing capscrews for these models are the same length of 110 mm
(4.375 in.).
9. On models 760A, 760B, 765, and 765A, install a washer on each bolt, and install into
housings (three bolts per housing).
All information subject to change without notice.
1-568
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
10. On models 760A and 765, move the housing from side to side, and locate the housing in
the center position of the movement. See Figure 1-452.
Figure 1-452
Locating Center Position of Housing
11. On models 760B and 765A, move the housing from side to side, and locate as far toward
the camshaft side of the engine as possible.
12. On all models, torque the engine brake capscrews using the following sequence:
[a] Torque the three bolts on the camshaft side of the engine to 55 N·m (40 lb·ft).
[b]
Torque the six bolts on the exhaust manifold side of the engine to 55 N·m (40 lb·ft).
[c] Repeat the tightening sequence and re-torque all bolts to 136 N·m (100 lb·ft).
[d]
Check the torque to 136 N·m (100 lb·ft).
13. Secure wire harness to spacer bars with plastic ties.
14. Connect wiring harness solenoid connectors to solenoids.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-569
1.29
JAKE BRAKE®
1.29.5.1
Adjustment of Slave Piston on Model 760, 765, or 770 Jake
Brake®
Make the following adjustment with the engine stopped and cold, and the oil temperature at 60C
(140F) or below. The exhaust valves on the cylinder must be in the closed position (rocker arm
roller on the base circle of the camshaft). When setting the engine brake lash, the exhaust valves
must be in the closed position. Adjust the slave piston on all models as follows:
NOTE:
The following procedures apply to Model 760, 765, and 770 Jake Brake®. For Model
790/795 Jake Brake® slave piston lash setting procedures, refer to section 1.29.8.1.
NOTE:
Model 770 Jacobs engine brake requires a special procedure for adjusting the slave
piston. The procedure is clearly indicated in the following adjustment steps.
NOTICE:
Improper slave piston adjustment can result in engine
or brake housing damage.
NOTICE:
Strictly follow the slave piston adjustment procedure. Failure to
use the proper adjustment procedure will result in poor engine
brake performance and/or serious engine damage.
1. Refer to section 1.29 for proper slave piston clearance setting.
All information subject to change without notice.
1-570
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
2. Back out the leveling screw in the slave piston assembly until the end of the screw is
beneath the surface of the bridge in the slave piston assembly. See Figure 1-453.
NOTE:
The leveling screw is located in the bridge member of the slave piston assembly.
1. Leveling Screw
Figure 1-453
2. Locknut
Location of Leveling Screw
3. On models 760, 760A, 760B, 765, and 765A, place the correct size feeler gage between
the solid side of the slave piston (the side without the leveling screw) and the exhaust
rocker arm adjusting screw. Feeler gage sizes are listed in Table 1.9 .
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-571
1.29
JAKE BRAKE®
4. On models 760, 760A, 760B, 765, and 765A, turn the slave piston adjusting screw
clockwise until a slight drag is felt on the feeler gage. See Figure 1-454.
1. Slave Piston Bridge
3. Feeler Gage
2. Slave Piston Adjusting Screw
Figure 1-454
Turn Slave Piston Adjusting Screw Clockwise
All information subject to change without notice.
1-572
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
5. Perform the following additional steps on model 770:
[a] Turn in the J-Lash™ adjusting screw until the solid side of the slave piston bridge
assembly contacts the exhaust valve and the valve springs begin to compress. Turn
in one additional turn.
NOTICE:
All oil must be purged from the J-Lash adjusting screw. Oil
remaining in the J-Lash screw will cause inaccurate clearance
adjustment, resulting in possible engine or engine brake damage.
If oil is below room temperature (below 60F), wait at least two
minutes for oil to be purged from the J-Lash adjusting screw.
NOTE:
Wait at least 30 seconds for oil to be purged from the J-Lash™ adjusting screw.
[b]
Back out the adjusting screw only until the correct size feeler gage can be inserted
between the solid side of the slave piston bridge assembly and the exhaust valve.
[c] Adjust the J-Lash™ so that a light drag is felt on the feeler gage.
NOTE:
Do not back out the J-Lash™ more than required to obtain a light drag on the feeler gage.
[d]
Use a screwdriver to hold the J-Lash™ in place, and torque the lock nut to 34 N·m
(25 lb·ft).
NOTE:
If the J-Lash™ screw is backed out until it no longer compresses the slave piston spring,
oil will enter the screw and the adjustment will be incorrect. If this occurs, repeat the
J-Lash™ adjustment procedure.
[e] Recheck the lash settings. If clearance setting is incorrect, repeat the J-Lash™
adjustment procedure.
NOTE:
Once the engine brake has been run, oil enters the J-Lash™ screw making the
engine brake adjustment unreadable. If unsure of the adjustment, repeat the J-Lash™
adjustment procedure.
6. On all models, hold the screw in position, and torque the locknut to 34 N·m (25 lb·ft).
7. Check the adjustment, and repeat if necessary.
NOTE:
Do not disassemble the slave piston adjusting screws.
8. Place the correct feeler gage between the leveling screw and the rocker arm adjusting
screw.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-573
1.29
JAKE BRAKE®
9. Turn the leveling screw clockwise until a slight drag is felt on the feeler gage.
See Figure 1-455.
1. Feeler Gage
3. Rocker Arm Adjusting Screw
2. Slave Piston Leveling Screw
Figure 1-455
Setting Clearance on Leveling Screw and Rocker Arm Adjusting
Screw
10. Hold the leveling screw in position, and torque the locknut to 47 N·m (35 lb·ft).
11. Check adjustment, and repeat if necessary.
12. Repeat the adjustment procedures for the remaining cylinders. Refer to step 2 through
step 11.
NOTE:
Bar over the engine when necessary to place the exhaust valves in the closed position
for slave piston adjustment.
13. Install the engine rocker cover. Refer to section 1.6.8 for one-piece, refer to section 1.6.9
for two-piece and three-piece.
14. Install all remaining components that were removed for this procedure.
15. Connect starting power for the engine.
16. Verify proper Jake Brake® installation by driving the vehicle, then checking engine brake
performance.
All information subject to change without notice.
1-574
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1.29.6
Removal of Model 790/795 Jake Brake® Assembly
Remove the Model 790/795 Jake Brake® as follows:
To avoid injury from hot surfaces, allow engine to cool before
removing any component. Wear protective gloves.
To avoid injury from accidental engine startup while servicing
the engine, disconnect/disable the starting system.
1. With the engine at ambient temperature and power to the starting system disconnected;
refer to section 1.6.2 for a one piece rocker cover, refer to section 1.6.3 for a two piece
rocker cover for diesel, refer to section 1.6.4 for a two piece rocker cover for gas,
refer to section 1.6.5 for a three piece rocker cover, and remove the engine rocker cover.
NOTE:
If the engine has a two-piece cover, the lower valve cover base does not have to be
removed to gain access to the engine brake housings.
2. Note the location of the rocker arm shaft, the exhaust valve rocker arm, the fuel injector
rocker arm, and the intake valve rocker arm.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-575
1.29
JAKE BRAKE®
3. Disconnect the lead wires from each of the solenoid valves and the wire harness clips.
See Figure 1-456.
1. Solenoid Valve
13. Control Valve Cover
2. Solenoid Upper Seal Ring
14. Retaining Ring
3. Solenoid Center Seal Ring
15. Adjusting Screw*
4. Solenoid Lower Seal Ring
16. Locknut
5. Master Piston
17. Slave Piston
6. Master Piston Pushrod
18. Slave Piston Bridge
7. Master Piston Spring
19. Outer Slave Piston Spring
8. Master Piston Retainer
20. Inner Slave Piston Spring
9. Master Piston Retaining Ring
21. Spacer Tube
10. Control Valve
22. Shoulder Bolt
11. Outer Control Valve Spring
23. Drive Screw
12. Inner Control Valve Spring
24. Wire Harness Clip
*Note that Model 790 Jake Brake® uses a J-Lash™ assembly. Model 795 Jake Brake® uses a solid screw.
Figure 1-456
Typical Model 790/795 Jake Brake® Assembly
All information subject to change without notice.
1-576
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
4. Remove the six capscrews and nut that secure the engine brake housing. See Figure 1-457.
1. Capscrew - 170 mm long
3. Stud Bolt
2. Capscrew - 140 mm long
4. Nut
Figure 1-457
Model 790/795 Jake Brake® Fasteners
5. Remove the engine brake housing.
6. Repeat steps 1 through step 5 to remove the second Jake Brake® housing.
7. Retain the six spacer tubes. See Figure 1-456.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-577
1.29
JAKE BRAKE®
1.29.6.1
Disassembly of Model 790/795 Jake Brake®
Disassemble Model 790/795 Jake Brake® as follows:
NOTICE:
To avoid possible engine damage, do not disassemble
or tamper with the solenoid valve.
1. Unscrew and remove the solenoid valve with a 3/4 in.-6 point socket and extension.
Discard the three solenoid seal rings. See Figure 1-458.
NOTE:
If the lower solenoid seal ring stays in the bottom of the housing bore, remove with
a piece of wire or small 90 degree pick.
All information subject to change without notice.
1-578
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1. Solenoid Valve
13. Control Valve Cover
2. Solenoid Upper Seal Ring
14. Retaining Ring
3. Solenoid Center Seal Ring
15. Adjusting Screw*
4. Solenoid Lower Seal Ring
16. Locknut
5. Master Piston
17. Slave Piston
6. Master Piston Pushrod
18. Slave Piston Bridge
7. Master Piston Spring
19. Outer Slave Piston Spring
8. Master Piston Retainer
20. Inner Slave Piston Spring
9. Master Piston Retaining Ring
21. Spacer Tube
10. Control Valve
22. Shoulder Bolt
11. Outer Control Valve Spring
23. Drive Screw
12. Inner Control Valve Spring
24. Wire Harness Clip
*Note that Model 790 Jake Brake® uses a J-Lash™ assembly. Model 795 Jake Brake® uses a solid screw.
Figure 1-458
Typical Model 790/795 Jake Brake® Assembly
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-579
1.29
JAKE BRAKE®
2. Repeat step 1 for removal of the remaining solenoid valves.
To avoid injury from flying parts when working with
components under spring tension, wear adequate eye
protection (face shield or safety goggles).
3. Press down the control valve cover using an appropriate diameter rod to relieve spring
pressure, while slowly removing the retaining ring with snap ring pliers until spring
pressure ceases. Remove the two control valve springs. Discard all these parts.
See Figure 1-458.
4. Using needle-nose pliers, reach into the bore and grasp the stem of the control valve.
Remove and discard the control valve. See Figure 1-458.
5. Repeat step 3 and step 4 for removal of the remaining control valves. See Figure 1-458.
6. Loosen all the locknuts; remove the adjusting screws and locknuts from housing.
See Figure 1-458.
NOTE:
For Model 790 Jake Brakes® remove the J-Lash™ assembly screw. For Model 795 Jake
Brakes® remove the solid screw.
7. Repeat step 6 for removal of the remaining adjusting screws and locknuts.
See Figure 1-458. Retain the adjusting screws and locknuts.
8. Turn the Jake Brake® housing over.
9. Press down the master piston retainer, while slowly removing the master piston retainer
ring with snap ring pliers until spring pressure ceases. See Figure 1-458.
10. Remove and save the master pistons and push rods. See Figure 1-458.
11. Repeat step 9 and step 10 for removal of the remaining master pistons. Discard the master
piston springs, retainers and retaining rings. See Figure 1-458.
12. Carefully remove the shoulder bolt and springs that retain the slave piston.
See Figure 1-458. Discard the inner and outer slave piston springs.
13. Remove and save the slave piston bridge and the slave pistons. See Figure 1-458.
14. Repeat step 12 and step 13 for removal of the remaining slave pistons. See Figure 1-458.
All information subject to change without notice.
1-580
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1.29.6.2
Cleaning of Model 790/795 Jake Brake®
Clean the Jake Brake® as follows:
1. Clean all parts in an OSHA-approved cleaning solvent.
To avoid injury from flying debris when using compressed air,
wear adequate eye protection (face shield or safety goggles)
and do not exceed 40 psi (276 kPa) air pressure.
2. Dry components with compressed air.
3. Coat all (new and reuse) components to be installed into the housings with clean engine
lube oil.
1.29.6.3
Inspection of Model 790/795 Jake Brake®
The Jacobs engine brake is typically a trouble-free device. However, inspections are necessary
and some maintenance is required. Use the following procedures to keep the engine brake in top
condition.
Inspect the Jake Brake® as follows:
1. Inspect the master piston bore for wear or damage.
NOTE:
Some wear marks are permissible.
[a] If worn or damaged, replace the master piston.
[b]
If not worn or damaged, continue with inspection.
2. Inspect the master piston and push rod for wear or damage.
NOTE:
Some wear marks are permissible.
[a] If worn or damaged, replace the master piston or push rod.
[b]
If not worn or damaged, continue with inspection.
3. Apply clean lube oil to the piston, and insert into bore.
NOTE:
Master piston should move in and out freely with no binding.
[a] If binding occurs, replace master piston and/or housing.
[b]
If no binding occurs, continue with inspection.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-581
1.29
JAKE BRAKE®
4. Inspect slave piston components for excessive wear or damage.
[a] If worn or damaged, replace slave piston component.
[b]
If not worn or damaged, proceed with inspection.
5. Inspect the control valve bore for wear or damage.
NOTE:
Some wear marks are permissible.
[a] If worn or damaged, replace the housing.
[b]
If not worn or damaged, continue with inspection.
6. Inspect adjusting screw for excessive wear or damage.
[a] If worn or damaged, replace adjusting screw.
[b]
If not worn or damaged, proceed with inspection.
NOTE:
Model 790 Jake Brake® uses a J-Lash™ assembly. Model 795 Jake Brake® uses
a solid screw.
7. Inspect capscrews for excessive wear or damage.
[a] If worn or damaged, replace capscrews.
[b]
If not worn or damaged, proceed with inspection.
8. Inspect spacer tubes for excessive wear or damage.
[a] If worn or damaged, replace spacer tubes.
[b]
If not worn or damaged, proceed with inspection.
9. Inspect locknuts for excessive wear or damage.
[a] If worn or damaged, replace locknuts.
[b]
If not worn or damaged, proceed with inspection.
10. Inspect solenoid for excessive wear or damage.
[a] If worn or damaged, replace solenoid.
[b]
If not worn or damaged, proceed with inspection.
11. Inspect solenoid bore for excessive wear or damage.
[a] If worn or damaged, replace solenoid.
[b]
If not worn or damaged, proceed with inspection.
All information subject to change without notice.
1-582
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
1.29.7
Assembly of Model 790/795 Jake Brake®
Assemble Model 790/795 Jake Brake® as follows:
1. Insert slave piston into bore. See Figure 1-459.
1. Solenoid Valve
13. Control Valve Cover
2. Solenoid Upper Seal Ring
14. Retaining Ring
3. Solenoid Center Seal Ring
15. Adjusting Screw*
4. Solenoid Lower Seal Ring
16. Locknut
5. Master Piston
17. Slave Piston
6. Master Piston Pushrod
18. Slave Piston Bridge
7. Master Piston Spring
19. Outer Slave Piston Spring
8. Master Piston Retainer
20. Inner Slave Piston Spring
9. Master Piston Retaining Ring
21. Spacer Tube
10. Control Valve
22. Shoulder Bolt
11. Outer Control Valve Spring
23. Drive Screw
12. Inner Control Valve Spring
24. Wire Harness Clip
*Note that Model 790 Jake Brake® uses a J-Lash™ assembly. Model 795 Jake Brake® uses a solid screw.
Figure 1-459
Typical Model 790/795 Jake Brake® Assembly
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-582a
1.29
JAKE BRAKE®
2. Install slave piston bridge. See Figure 1-459.
To avoid injury from flying parts when working with
components under spring tension, wear adequate eye
protection (face shield or safety goggles).
3. Install new springs and shoulder bolt. Torque bolts to 23 N·m (16 lb·ft). See Figure 1-459.
4. Repeat step 1 through step 3 for installing the remaining slave pistons.
5. Install the master piston and pushrod into the bore. See Figure 1-459.
6. Install new spring. See Figure 1-459.
7. Install new master piston retainer over spring. See Figure 1-459.
8. While depressing master piston retainer, insert the new master piston retaining ring with
snap ring pliers. See Figure 1-459.
NOTE:
Rotate the retaining rings 90 degrees to ensure that the ring is seated in the groove.
9. Repeat step 5 through step 8 for installing the remaining master pistons.
10. Flip housing over.
11. Install the adjusting screw and locknut. See Figure 1-459.
NOTE:
For Model 790 Jake Brakes® install the J-Lash™ assembly screw. For Model 795 Jake
Brakes® install the solid screw.
NOTE:
Do not tighten the locknut at this time.
12. Repeat step 11 for installing the remaining adjusting screws and locknuts.
13. Slip the new control valve into the bore. See Figure 1-459.
14. Install new control valve springs. See Figure 1-459.
15. Place new control valve cover over springs followed by the retaining ring.
See Figure 1-459.
16. Press down on the valve control cover with an appropriate diameter rod and set the
retaining ring into the groove with snap ring pliers. See Figure 1-459.
NOTE:
Rotate the retaining ring 90 degrees to ensure that the retaining ring is seated in the
groove.
All information subject to change without notice.
1-582b
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
17. Repeat step 13 through step 16 for installing the remaining control valves.
18. Install the lower (smallest) solenoid seal ring into the bottom of the solenoid valve bore.
See Figure 1-459 and see Figure 1-460.
NOTE:
Coat the seals with clean engine oil prior to assembly.
NOTE:
New upper seal rings can be identified by a yellow stripe.
1. Seal Rings (3)
Figure 1-460
2. Solenoid Valve
Installation of Solenoid Valve Seal Rings
19. Install the upper and center seal rings on the solenoid valve. See Figure 1-459 and
see Figure 1-460.
NOTE:
Coat the seals with clean engine oil prior to assembly.
NOTICE:
Avoid cutting or twisting the seal rings while installing solenoid.
Improper installation could result in poor engine brake performance.
20. Ensure the solenoid seal rings are seated properly.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-582c
1.29
JAKE BRAKE®
21. Using a 3/4 in.-6 point socket and extension; carefully screw in the solenoid valve into
the housing without unseating the solenoid seal rings. Torque to 20 N·m (15 lb·ft).
See Figure 1-459.
22. Repeat step 18 through step 21 for installing the remaining solenoid valves.
1.29.8
Installation of Model 790/795 Jake Brake® Assembly
The installation procedures for the model 790/795 Jake Brake® assemblies differ slightly from
the former engine brakes. Two brake housings are used, instead of three, and spacer bars are not
required. Install the model 790/795 Jake Brake® assemblies as follows:
NOTICE:
To prevent cylinder head from cracking when bolts are
torqued, remove the oil from the bolt holes.
To avoid injury from flying debris when using compressed air,
wear adequate eye protection (face shield or safety goggles)
and do not exceed 40 psi (276 kPa) air pressure.
1. Attach a length of tubing to an air gun nozzle and blow out the oil from the housing-hold
down bolt holes.
NOTE:
Cover the holes with hand towels to minimize oil spray.
2. Place the engine brake housings on the rocker shafts and spacer tubes with the solenoids
on the camshaft side of the engine and the slave pistons over the exhaust valves.
3. Lubricate each hold-down capscrew with clean engine oil.
4. Install three 170 mm long capscrews on the solenoid side of the brake. See Figure 1-460a.
All information subject to change without notice.
1-582d
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
Figure 1-460a
Housing Hold-Down Bolt Locations
NOTICE:
Installing 170 mm capscrews on the exhaust side of the
engine can result in serious engine damage.
5. Install three 140 mm long capscrews on the exhaust side of the engine. See Figure 1-460a.
6. Before tightening the capscrews, move the housing from side to side. Position housing in
the center of the range of motion.
7. Tighten the capscrews in the following sequence for one engine brake assembly:
(See Figure 1-460a.)
[a] Starting with the middle capscrew, torque the three capscrews on the camshaft side of
the engine to 55 N·m (40 lb·ft).
[b]
Starting with the middle capscrew, torque the three bolts on the exhaust manifold
side of the engine to 55 N·m (40 lb·ft).
[c] Torque the nut at the end of the rocker shaft to 55 N·m (40 lb·ft).
[d]
Repeat the tightening sequence, torquing all capscrews to 136 N·m (100 lb·ft).
[e] Repeat step 7[a] through step 7[d] for the other engine brake.
8. Connect the lead wires to the solenoid valves passing the wires through the wire clips.
9. Torque solenoid screw to 1 N·m (9 lb·in.).
NOTE:
Pull the lead wires away from the housing.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-582e
1.29
JAKE BRAKE®
1.29.8.1
Set Slave Piston Lash
The slave piston lash must be set after Jake Brake® housings are installed. Adjustments must
be made with the engine stopped and cold with the oil temperature at 60C (140F) or below.
Exhaust valves on the cylinder must be in the closed position (rocker arm roller should be on the
base circle of the camshaft).
NOTICE:
The slave piston adjustment procedure must be followed
exactly. Failure to properly adjust Jake Brakes® will result
in inefficient engine brake performance and may lead to
severe engine or Jake Brake® damage.
Adjust Model 790/795 Jake Brake® slave piston lash as follows:
1. Back out the adjusting screws on the slave pistons until the slave piston does not touch
the rocker arm.
2. Insert the correct feeler gage (listed in Table 1-9 ) between the slave piston and the exhaust
rocker adjusting screw. See Figure 1-460b.
1. J-Lash Adjusting Screw
3. Exhaust Valve Spring
2. Slave Piston
Figure 1-460b
Setting Slave Piston Lash
All information subject to change without notice.
1-582f
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
3. Using a 3/16 in. hex wrench, turn in the adjusting screw until the slave piston contacts the
exhaust rocker adjusting screw through the feeler gage. Adjust the screw until a slight
drag is felt on the feeler gage.
NOTE:
For Model 795 applications, skip to step 7.
4. For J-Lash™ installation only, continue turning in the adjusting screw until the valve
springs begin to compress, then turn in one additional turn.
5. Wait at least 30 seconds for oil to be purged from the J-Lash™ adjusting screw.
NOTE:
All oil must be purged from the J-Lash™ adjusting screw. If oil is below 16C (60F), wait
at least two minutes for oil to be purged from the J-Lash™ adjusting screw.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-582g
1.29
JAKE BRAKE®
NOTICE:
Serious engine damage may occur from improper lash setting.
6. After the time interval specified in step 5, back out the adjusting screw ONLY until a slight
resistance is felt on the feeler gage. See Figure 1-460c.
NOTE:
Do not retract more than required to obtain a light drag on the feeler gage.
NOTE:
If the J-Lash™ adjusting screw is backed out until it no longer compresses the slave
piston spring, oil will enter the screw and the adjustment will be incorrect. If this occurs,
repeat step 1 through step 5.
1. J-Lash Adjusting Screw
3. Feeler Gage
2. Locknut
Figure 1-460c
Adjusting Slave Piston Lash
All information subject to change without notice.
1-582h
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
SERIES 60 SERVICE MANUAL
7. Hold the solid adjusting screw in place and torque the locknut to 38 N·m (28 lb·ft).
8. Recheck lash settings. If lash setting is incorrect, repeat step 1 through step 6.
NOTE:
Once the engine brake has been run, you will not be able to check the engine brake
adjustments for engines using J-Lash™ adjusting screws. This is because of oil retained
in the J-Lash™ adjusting screw. If unsure of the adjustment, repeat step 1 and step 7.
9. Repeat step 1 through step 8 for the remaining slave piston on the same cylinder.
10. Repeat step 1 through step 8 for the remaining cylinders.
To avoid injury, wear a face shield or goggles.
To avoid injury from fire, contain and eliminate
leaks of flammable fluids as they occur. Failure to
eliminate leaks could result in fire.
11. Install all remaining components that were removed for this procedure.
NOTE:
Ensure that all wires are away from moving parts.
12. Complete the installation by installing the rocker cover. Refer to section 1.6 .
13. Start and drive the vehicle to verify proper Jake Brake® performance.
All information subject to change without notice.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
From Bulletin 2-60-01Rev.
1-582i
1.29
JAKE BRAKE®
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All information subject to change without notice.
1-582j
From Bulletin 2-60-01Rev.
6SE483 0010 Copyright © 2001 DETROIT DIESEL CORPORATION
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