Service Manual

Operation & Maintenance Manual for WP7 Euro Ⅵ
Vehicle Diesel Engine
15
3.7 Unstable speed
Causes
Troubleshooting
1. Poor quality fuel, containing too
much water or wax
Clean the fuel system and replace the fuel
2. Air comes into the fuel suction pipe
Check the tightness of fuel pipes and the joints;
release the air
3. Governor weight and spring do not
work normally
Check and repair (by specialized operator)
4. Uneven fuel supply
Check and adjust (by specialized operator)
5. Poor atomization of the injector
nozzle
Check and repair
6. The turbocharger surges
Check the compressor flow passage and
remove the blockage, remove the carbon
deposit in the exhaust path
7. Turbocharger bearing is broken
Replace
3.8 Low oil pressure
Causes
Troubleshooting
1. Low oil level in the oil sump or lack
of oil
Check the oil level and leakage; repair and add
oil
2. Failure of pressure regulator in the
main oil passage
Check, clean and repair the valve
3. Oil strainer, oil pipe, joint gaskets are
blocked or broken
Check the oil strainer and joints, repair the
casting shrinkage porosity if any
4. Unqualified oil grade
Replace with qualified grade
5. Oil inlet pipe of the engine oil pump
leaks
Examine the oil pipe, joints; repair or replace
6. The temperature of water in cooling
system is too high, and temperature of
lubricating oil is too high
Check the working conditions of cooling
system, and correct
7. The resistance of oil filter is too big
Replace with a new element
8. Oil cooler is blocked
Check and remove the blockage
9. The main oil passage is blocked
Check and remove the blockage
10. Excessive bearing clearance or the
bearing is damaged
Check and repair
11. Excessive wear of parts, overhaul is
required
Check the working hours of the engine and
carry out an overhaul