FAW Jiefang Automotive 485, Operation & Maintenance Manual

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Trouble causes Remedial methods
V. Abnormal sound
1. Fuel-supply advance angle is too big, and
metal-knock rhythmic sound can be heard from
inside of cylinder.
2. Oil nozzle drips oil, and needle valve is
jammed, causing the sound like "ta, ta, ta".
3. Valve clearance too big, and clear and
rhythmic knocking-sound
4. Piston collides with valve, causing heavy and
rhythmic knocking-sound (if put a hand at nut
on cylinder cover, vibration can be felt).
5. Piston collides with the bottom of cylinder
cover, causing heavy and strong
knocking-sound.
6. Valve spring is broken, valve push-rod is
bent, valve tappet is worn off, causing valve
mechanism to produce slight knocking-sound.
7. Sound due to too much gap between piston
and cylinder jacket. This sort of sound will be
reduced, with the engine being warmed up.
8. If connecting rod bearing gap is too big,
when speed is abruptly reduced, heavy and
strong knocking-sound can be heard.
9. Gap between connecting rod bush and piston
pin is too big. This sound is low but sharp, and
10. If crankshaft thrust-piece is worn off, gap is
too big, the collision sound of crankshaft
playing back and forth can be heard.
1. Adjust the advance angle.
2. Clean, repair or replace the needle valve
couple.
3. Adjust valve clearance.
4. Increase the valve clearance a little bigger,
correct the gap of connecting rod's bearing,
or replace the rod's bush.
5. Replace cylinder cover gasket.
6. Replace the spring, push-rod or tappet etc,
and adjust valve clearance.
7. Depending wearing conditions, determine
if cylinder jacket and piston are to be
replaced.
8. Replace connecting rod's bush.
9. Replace connecting rod's bush
10. Replace the thrust-piece of crankshaft.
VI. Severe vibration
1. Oil-supply for each cylinder is not uniform;
oil nozzle of one or two cylinders has poor
atomization; one or two cylinders severely leak;
compression ratio difference is big, etc.
2. Water or air enters into diesel oil.
3. Poor alignment when the engine is installed;
support's bolts are loosened.
4. Cylinder(s) is heavily knocked. Engine
works roughly.
1. Inspect and adjust oil-supply rate of
fuel-injection pump; repair the oil nozzle;
eliminate the leakage problem; inspect and
adjust compression pressure of each
cylinder.
2. discharge the air; make the diesel oil to be
deposited.
3. Correct the alignment; tighten them.
4. Inspect the fuel-supply advance angle;
apply load after engine is warmed up.
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