- Extraneous noise due to a malfunction of the hydraulic pusher occurs immediately after starting the engine and changes in accordance with the engine speed. However, this noise does not depend on the actual load on the motor. Therefore, if the noise does not occur immediately after starting the engine, if it does not change according to the engine speed or changes according to the engine load, then the hydraulic tappets are not the cause of the noise.
- In the event of a malfunction of the hydraulic pushers, the noise almost never disappears even when the engine is idling after it has warmed up. The only time the noise may go away is when changing the engine oil (the knock of the hydraulic pushers in this case is caused by the formation of sediment in the engine oil).
Start the engine.
Check that the noise appears immediately after starting the engine and that the noise changes according to the change in engine speed.
If the noise does not appear immediately after starting the engine, or if it does not change in accordance with the change in engine speed, the malfunction is not caused by a malfunction of the hydraulic tappets, look for another cause of the malfunction.
When the engine is idling, make sure that the noise level does not change with changes in engine load (for example, when switching the selector from the position «N» into position «D»).
If the noise level fluctuates, the cause may be the impact of parts due to worn crankshaft bearings or connecting rod bearing shells.
After the engine has warmed up, let it idle and check for abnormal noise. If the noise decreases or disappears, the tappet noise may be due to contaminated engine oil. Wash hydraulic lifters.
Remove air from pushers.
If the noise does not disappear even after removing the air, clean the hydraulic pushers.