M119 Water Pump R&R
R&R’ing the M119's water pump isn't too difficult, if you have the proper tools (pulley
counter-hold; reverse Torx socket for updated tensioner; (2) 3-ft. prybars; and 1/4-drive
sockets/wrench) and a good/accurate and small torque-wrench (I have a Mountz 1/4"-drive
that reads 0-30 Nm in quarter Nm increments).
Here are some caveats/tips:
1) clean the front of the engine with a good engine degreaser;
2) use a THIN coating of Hylomar sealant on all gaskets;
3) clean with a bronze wire-wheel and rinse with brake cleaner ALL bolts;
4) use high-temp anti-seize on all bolts (steel) that go into aluminum;
5) you do NOT need to remove the radiator, just the viscous-fan/clutch assembly and
shroud;
6) you do NOT need to remove the lower alternator bolt, just loosen it;
7) if you do NOT have a pulley-holder, use an air-ratchet to loosen the water pump and
idler pulley bolts (NOT tensioner pulley) with the serpentine belt still on (acts as a counter
hold);
8) use different colored paint on the bolts to keep track of them and write-down the key/
legend;
9) turn the crankshaft bolt (CLOCKWISE ONLY) to TDC and mark with paint the orientation/
location of the following: pulley to harmonic dampener; harmonic dampener to crankshaft
bolt);
10) soak the CENTER of the harmonic damper to crankshaft bolt with AeroKroil; PB
Blaster, or a good quality penetrant (e.g., AeroKroil), preferably overnight;
11) you do NOT need to remove the crankshaft bolt (400Nm) to remove the dampener;
12) remove the dampener using TWO 3-ft pry-bars (left & right side) by gently wiggling out
the dampener and being careful where you brace the pry-bar for leverage;
12) gently clean the mating surface of the engine block to water pump with a bronze wirewheel and wipe-down with brake-cleaner and number the bolts;
13) REPLACE the thermostat (clean all hose connectors and mating surfaces);
14) place a rag under the REAR thermostat housing's bolt so if it drops, it doesn't go into
never-land and have spare M6-20mm bolts;
15) use anti-seize on the thermostat cover bolts and NOTE only 10-Nm on these;
16) use a heat gun on LOW or a hair-dryer to "soften" the water-pump's weep-hole pipe
and then gently tug off the water pump and use the same heat source to "soften" the pipe
when re-installing;
17) remove the pipe and tank (one bolt) to make disassembly easier;
18) when replacing the idler-pully bracket, keep the bolts with enough slack since you have
to align/bolt-up back the air pump; alternator AND bracket back to the block;
19) when replacing the thermostat elbow hose, smear a little Hylomar on the metal hose
housings to facilitate moving/bending the hose into place;
20) REPLACE the hose between the thermostat TOP housing and INTAKE and the gasket
(thin film of Hylomar);
21) DO NOT OVER TIGHTEN esp. with anti-seize on bolts and into aluminum. Most bolts
are 21 Nm, but with anti-seize on them, it's closer to 12-15 Nm. Do NOT use a 3/8-drive
ratchet to put any bolts ON, only 1/4-drive with about a 5-inch long handle so I don't overly
torque anything.
BTW: I use a vacuum-based coolant installer that basically uses the compressed-air to
create a vacuum in the cooling system, and then by flipping a valve, I suck in my 70%
distilled water and 30% G05/Mercedes coolant with Redline Water-wetter.
Hope this helps!
:-) neil
1988 E36T AMG
1993 500E
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