Chery QQ Service Manual 465 Engine Mechanical System
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Chery Automobile Co., Ltd
c It is probably due to valve if pressure of the first stroke is too low and it remains low in
afterwards strokes or the pressure keep the former state after being injected with oil.
d It is probably due to cylinder head gasket if pressure of two neighboring cylinders is too
low or there is some coolant in the crankcase.
11 Remove the limit stop from throttle valve plate
12 Install vacuum pipe to throttle valve body
13
Install spark plug
II General introduction to diagnosis of engine noise
Notice: Comparing with sound of other engines, you should make sure that you are not
giving a lot of trouble to maintain the normal one, because some engines have normal special
noise out of consideration of design.
The following 4 factors shall be considered when you make diagnosis of engine noise:
● Classification of noise
● Conditions for noise to happen
● Frequency for noise to happen
● Position for noise to happen in the engine
Noise of engine is usually synchronous with engine speed(results from connecting rod or
piston)or half of engine speed(valve train).You should try to make sure frequency of the
noise.
1 Main bearing noise
Noise results from main bearing damage or wear is just like the sound of thud or knocking ,
it happens once every circle that the engine rotate, the noise comes to maximum when the
engine works with heavy load, knock of interval knocking sound which is much more
piercing than the main bearing wear noise, shows that clearance of crankshafts is too big.
The following conditions can lead to main bearing noise:
l
The pressure of oil pump is too low.
l
The oil is too thin or/and the oil filter is too dirty.
l
The clearance of main bearing is too big.
l
The end clearance of crankshaft is too big.
l
The shaft journal of crankshaft is out of round.
l
Belt tension is too high.
l
Crankshaft pulley is not tight enough.
l
Main bearing cover is not tight enough.
l
Driving belt pills.
2 Connecting rod bearing noise
Sound of knocking is generated at all speed under the condition of connecting rod bearing
being damaged or wear ,connecting rod noise and knocking sound of piston or looseness of
piston pin may be confused together easily in early stage of connecting rod bearing damage,
knocking sound of connecting rod will become louder along with engine speeding up, this
noise comes to maximum while decelerating.
The following circumstances can be the cause of noise:
