Chery QQ Service Manual 465 Engine Mechanical System
- 8 –
Chery Automobile Co., Ltd
relationship between the knock and bearing.
5 Valve train noise
Valve train malfunction can be shown by means of slight slapping sound of any frequency or
frequency is equal to half of engine speed, the noise will go up along with acceleration of the
engine.
First, warm up the engine before judging the valve train noise, so as to make the engine parts
expand to normal state. Listen to engine noise under the circumstance of engine cover being
shut.
Remove out the rocker arm head ,make sure the parts of valve train which result in noise
with stethoscope, if the noise of valve train is abnormal. The cause of noise are introduced as
follows:
l
Valve spring fracture, resiliency of valve spring is not enough.
l
Valve is blocked or curved
l
Rocker is curved
l
The cam of camshaft is damaged or poor performance.
l
Lubrication of valve train is not good or oil pressure is too low.
l
The clearance of valve stem and valve guide pipe is too big.
l
Valve guide pipe wear
l
Push rod wear
l
Valve rocker wear
l
Bolt of valve rocker fracture
l
Auxiliary parts of valve rocker is too loose or wearing.
III Diagnosis of engine noise
1 Exhaust gear
Symptom
Cause of malfunction/ Troubleshooting
Vibration or quack
noise of exhaust
system
Looseness or malposition of exhaust parts, you can carry out
the following procedures:
1 Align the joints.
2 Fasten the joints.
3 Check to see whether or not exhaust lifting hook , mounting
bracket and clamp are damaged.
Waste gas leak or
noise
The following conditions can result in waste gas leak or noise:
l
Exhaust parts joints or connection leak.
l
Tighten clip or connecting parts to regulated torque.
l
Installation of exhaust system is not correct or malposition.
l
Align and tighten the clip.
l
There are some cracks on the exhaust manifold.
l
Leakage between exhaust manifolds or between the
cylinder heads.
l
Fasten the exhaust manifold on the cylinder head according
