DAF LF45, LF55 Series. Manual - part 302

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General

BE ENGINE INLET/EXHAUST SYSTEM

ΛΦ45/55 series

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2.2 SYSTEM DESCRIPTION, TURBOCHARGER WITH WASTEGATE

To make the engine more responsive at lower 

engine speeds, a turbocharger is used that 

produces a better charge ratio at these speeds. 

Without provision having been made for this, the 

boost pressure yielded by this turbocharger 

would be too high at maximum engine speeds. 

Use of a wastegate prevents this.

The boost pressure is measured by a diaphragm 

box (1) on the delivery side of the turbocharger. 

The diaphragm is pushed back against the spring 

pressure by the boost pressure. The linked 

control rod (2) is also pushed back. The control 

rod operates a valve in the turbine housing (3).

The valve in the turbine housing is opened when 

the maximum pre-set pressure has been 

reached.

When the valve is opened, some of the exhaust 

gases will be discharged directly to the exhaust 

pipe rather than being used to propel the turbine 

rotor of the turbocharger.

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BE ENGINE INLET/EXHAUST SYSTEM

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©

 200416

General

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ΛΦ45/55 series

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©

 200416

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Inspection and adjustment

BE ENGINE INLET/EXHAUST SYSTEM

ΛΦ45/55 series

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3. INSPECTION AND ADJUSTMENT

3.1 INSPECTING TURBOCHARGER WASTEGATE

Note:

Depending on the fitting position of the 

turbocharger, it may be necessary to remove the 

turbocharger from the engine before this 

adjustment; see "Removal and installation".

Note:

The turbocharger is calibrated in the factory and 

must not be re-adjusted. The length of the control 

rod on the wastegate valve lever may only be 

changed when assembling a new turbocharger. 

After that, only an inspection of the actuating 

pressure of the wastegate may be carried out. If 

the result is negative, the turbocharger must be 

replaced.

1.

Remove the flexible pipe (2) from the 

diaphragm box (1) of the wastegate.

2.

Connect an air-pressure reducer valve to the 

diaphragm box of the wastegate. Set the 

reducer valve to max. 0.2 bar gauge 

pressure. Connect the reducer valve to a 

compressed air installation.

3.

Set the reducer valve to exactly the same 

test pressure as listed in "Technical data".

4.

Check the diaphragm in the diaphragm box 

for leaks by listening carefully for a hissing 

sound from the diaphragm box.

5.

Check whether the control rod of the 

wastegate has moved. If it has not moved, 

the control rod must be loosened from the 

lever. Check again whether the control rod 

has moved. If is has not moved, the 

diaphragm box must be replaced. If it has 

moved, the wastegate valve must be made 

to move freely or, if that does not help 

sufficiently, the entire compressor unit must 

be replaced.

6.

Remove the flexible pipe with the reducer 

valve and re-connect the flexible pipe of the 

compressor pump to the wastegate 

diaphragm box.

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Inspection and adjustment

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ΛΦ45/55 series

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3.2 INSPECTING TURBOCHARGER AXIAL BEARING PLAY

Note:

The turbocharger axial bearing play should only 

be checked when the engine is cold.

1.

Remove the exhaust pipe from the 

turbocharger.

2.

Remove the charge pipes from the 

turbocharger.

3.

Fit a dial gauge (1) to the charge supply 

flange of the turbocharger.

4.

Push the compressor shaft away from the 

dial gauge and set the gauge to zero.

5.

Push the compressor shaft to the dial gauge 

and read off the axial play. Compare the 

reading with the specified value; see 

"Technical data". Replace the turbocharger if 

necessary.

6.

Fit the charge pipes to the turbocharger.

7.

Fit the exhaust pipe to the turbocharger.

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