Engine

Page 15

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Volvo Bus Service and Maintenance Manual

 Turbo-compressor
16 Check that the compressor wheel is clean and undamaged, that it rotates freely and has axial and radial clearance. The compressor wheel should not scrape against the housing when alternately pushed in and pulled out. Check that the oil pipe to the turbo-compressor is not damaged.
 
 Exhaust gas system
17 Check the following: joint tightness, condition and fitment of brackets and rubber mount pads, condition of exhaust pipe and silencer (tap with a hammer).
 
 Exhaust brake
18 Check condition.
 

Turbo-compressor

WARNING! Make sure the turbo has cooled before inspecting. Particularly the exhaust side can reach very high temperatures.

A dirty and oily compressor, a compressor housing not properly tightened can have a negative effect on the boost pressure and this in turn can affect engine output.

Accelerator pedal adjustmant

With the hose removed, check and if necessary clean the turbo-compressor mounted on the engine. The compressor wheel is cleaned with petrol.

When refitting the inlet hose, make sure it is correctly tightened to the compressor housing.

Turbo boost pressure

Prior to checking the boost pressure, when engine power is low, it may be necessary to check the air cleaner, fuel system and to make an engine compression test (concerning instructions on how to check the boost pressure, etc., refer to the Service Manual, Section 2, Engine).

Exhaust brake

Check that when activated the compressed-air cylinder closes the exhaust shutter. If the bus has an Allison automatic transmission, also check the interlock function for the engine speed. In this case the exhaust brake should be disengaged, in spite of the fact that it is activated, when engine speed drops below 900 r/min. This will prevent the engine (and thereby also the power steering pump) from stopping.

Accelerator pedal adjustmant

It must be possible to turn the compressed-air cylinder on its attachment in order to open and close the exhaust shutter. Check that the injection pump stop device activates at the same time as the exhaust brake.

Accelerator pedal adjustmant