Fault phenomenon: when the engine is running, there is a whoosh, whoosh, whoosh like noise, and the vibration is too large when changing speed.
Troubleshooting: in order to confirm the fault symptoms, i.e. start the engine test, the abnormal sound is very small and can not be heard clearly in the idle running state, but when the air conditioner switch is turned to on in the idle running state, the belt slip sound of swish, swish and swish will be produced instantly.
The belt slip of air conditioning compressor is the cause of abnormal noise of engine.
The reasons for the slippage are not only the aging of the belt, the poor belt tensioner, the poor tensioner adjuster, etc.
Secondly, it is confirmed that the vibration is too large when changing gears, such as from n to R, D and driving.
In driving test, the vibration of gear change is small when the gear change is from 3rd to 4th and from 4th to 3rd. The vibration of gear change is large when the gear change is from 1st to 2nd and from 2nd to 3rd.
The reasons for the excessive vibration of the transmission are the aging or fracture of the rubber coupling of the drive shaft, the high operating oil pressure of the automatic transmission or the poor parts inside the automatic transmission.
First of all, find out the reason of large vibration of variable speed, operate the variable speed selector repeatedly, and confirm the state of variable speed vibration.
The test results show that when changing from n gear to D gear, the clutch will make a hiss at the moment when it is closed, and a snap after the vibration, which can also be clearly confirmed on the driver's seat.
If this sound is generated by automatic transmission, it is very difficult to understand.
Lift up the car immediately and use it to rotate the drive shaft for a test. You can hear a small click when you swing your hand left and right.
Remove the drive shaft and find that the rubber coupling is deformed and will crack.
According to the above operation results, the defective parts, i.e. the driving belt, the belt tensioner and the tensioner adjuster of the air conditioning compressor, were replaced together.
The replacement effect of these three parts is better.
The rubber elastic coupling of the drive shaft was replaced because of the abnormal sound caused by the speed change.
After the operation, the test driving was carried out. As a result, the abnormal noise of the engine was completely eliminated, and the shifting vibration was also completely eliminated when shifting from n to driving and during driving