Rectifying low boost pressure. Volvo Penta TWD1620GH, TWD1630P, TAD1630G, TAD1631G, TAD1630GE, TWD1630G, TAD1631GE, TAD1630P, TAD1630V, TWD1630V

Service procedures - intake and exhaust systems

Rectifying low boost pressure

1.

Tightness of seals, inlet and exhaust manifolds.

It is essential that the hose between the turbocharger and the inlet manifold is not cracked or is inadequately clamped.

In addition to a loss in boost pressure, leakage can also cause a high exhaust gas temperature which will result in excessive stresses on the exhaust pipe, turbo, valves and piston rings.

An exhaust system operating with too large a counter pressure reduces boost pressure, gives a lower engine output and increases exhaust temperature with a related risk of burnt valves and turbo failure.

When an exhaust system has been rebuilt the back pressure must always be checked in accordance with the instructions given. See next page ”Checking exhaust back pressure”

The following demands must be met when converting an exhaust system:

A.

The diameter of the connecting pipe must be 1/2-1" larger than the pipe to which it is to be connected.

B.

The transition between the existing pipe, to which connection is being made, and the connecting pipe must not be abrupt. It should be tapered, the taper being about

180 mm long.

C.

The pipe elbows should have as large a radius as possible. ”Pleating” should be avoided.

Group 22

In the event of daily operation in dusty or oily air, regular cleaning of the compressor housing and compressor wheel is recommended. Fouled compressor parts can result in low boost pressure.

The compressor parts can be cleaned with the unit fitted as follows:

Remove the compressor housing. Clean the compressor housing, compressor wheel and the end head in kerosene or the like. Fit the compressor housing and measure the boost pressure again.

5.

Injection pump

Check the following:

Governing, injection angle, calibration, fast idle, smoke eliminator diaphragm and triggering point, curve plate setting and sealing.

6.

Feed pressure

Check that fuel leakage does not occur and that the pump provides the correct feed pressure.

2.

Air filter

Check that the air filters are not blocked and that the correct filters are being used. The indicator on the air filter inlet pipe must not show red. Replace the filters when necessary.

3.

Accelerator linkage

Check that the accelerator linkage provides full travel of the injection pump arm.

4.

Turbocharger

Check if the rotor shaft is sluggish or if the turbine wheel and compressor wheel chafe against their housings. Turn the wheel at first with a slight pressure, and when with a slight axial pull. If the wheel is sluggish, the turbocharger must be immediately replaced or reconditioned. Check the wheel for damage.

7.

Delivery pipes

Check that the pipes are of the correct dimension and that the holes are not damaged.

8.

Injectors

Check the markings, opening pressure, spray pattern and that the holes are not faulty or blocked.

9.

Engine condition

Check the compression pressure and the valve clearance of the engine.

If the boost pressure remains unsatisfactory once all these points have been checked and approved, the turbocharger should be reconditioned or replaced.

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