DAF LF45, LF55 Series. Manual - part 285

©

 200416

3-3

Inlet/exhaust system

DIAGNOSTICS

ΛΦ45/55 series

4

1

Compressor side of turbocharger contaminated

Clean compressor side with a non-corrosive clean-

ing agent or a soft brush. Check the intake side for 

carbon deposits or other contamination

Gas leak between the exhaust manifold and the 

cylinder head

Check the fixing bolts and gaskets

Gas leak between the exhaust manifold and the 

turbocharger

Check the fixing bolts and gaskets

Turbocharger damaged

Replace the turbocharger and identify the cause

SYMPTOM: BLACK SMOKE EMERGES FROM EXHAUST

Possible cause

Remedy

SYMPTOM: BLUE SMOKE EMERGES FROM EXHAUST

Possible cause

Remedy

Air filter element blocked

Replace the air filter element

Air leakage between turbocharger and inlet mani-

fold

Check flexible pipes and pressurise intake unit

Air leakage between the inlet manifold and cylinder 

head

Check for leakage. Replace gaskets, if necessary

Compressor side of turbocharger contaminated

Clean compressor side with a non-corrosive clean-

ing agent or a soft brush. Check the intake side for 

carbon deposits or other contamination

Turbocharger oil discharge pipe clogged

Check oil pipe. Replace as necessary

Turbocharger damaged

Replace the turbocharger and identify the cause

SYMPTOM: OIL LEAK AT TURBINE SIDE OF TURBOCHARGER

Possible cause

Remedy

Compressor side of turbocharger contaminated

Clean compressor side with a non-corrosive clean-

ing agent or a soft brush. Check the intake side for 

carbon deposits or other contamination

Turbocharger oil discharge pipe clogged

Check oil pipe. Replace as necessary

Turbocharger damaged

Replace the turbocharger and identify the cause

SYMPTOM: OIL LEAK AT COMPRESSOR SIDE OF TURBOCHARGER

Possible cause

Remedy

Air filter element blocked

Replace the air filter element

Turbocharger oil pipe clogged

Check oil pipe. Replace as necessary

Turbocharger damaged

Replace the turbocharger and identify the cause

DIAGNOSTICS

3-4

©

 200416

Inlet/exhaust system

1

ΛΦ45/55 series

4

SYMPTOM: EXHAUST GAS BACK PRESSURE TOO HIGH

Possible cause

Remedy

Incorrect butterfly valve adjustment

Check the adjustment of the butterfly valve

Butterfly valve incorrectly positioned

Check whether the butterfly valve has been posi-

tioned correctly

Butterfly valve partially operated by residual pres-

sure in the operating cylinder

Check operating cylinder

Original exhaust silencer not fitted

Check exhaust silencer

Exhaust pipe crushed or internally blocked by a 

loose part

Check exhaust system for blockage and/or dam-

age

SYMPTOM: INLET UNDERPRESSURE TOO HIGH

Possible cause

Remedy

Air filter element blocked

Replace air filter element

©

 200416

4-1

Engine brake

DIAGNOSTICS

ΛΦ45/55 series

4

1

4. ENGINE BRAKE

4.1 INTRODUCTION

If there is a fault in the system, it is usually 

detected by the electronic unit in the form of a 

fault code. This fault code can be read out using 

DAVIE. The fault-finding table contains possible 

causes of symptoms not detected by the 

electronic unit. 

DIAGNOSTICS

4-2

©

 200416

Engine brake

1

ΛΦ45/55 series

4

4.2 FAULT-FINDING TABLE

SYMPTOM: ENGINE BRAKE DOES NOT ENGAGE

Possible cause

Remedy

Compressor delivering insufficient air pressure.

Check the operation of the compressor.

Air leak in the air pipe from air dryer to exhaust 

brake valve.

Check air pipe.

Butterfly valve stuck in butterfly valve housing.

Check free movement of butterfly valve.

Electrical fault.

Check electrical circuit.

SYMPTOM: ENGINE BRAKE REMAINS ENGAGED

Possible cause

Remedy

Butterfly valve stuck in butterfly valve housing.

Check free movement of butterfly valve.

Electrical fault.

Check electrical circuit.