The engine does not start
Engine runs rough or stalls at idle
The engine does not develop full power and does not have sufficient throttle response
Knocking of crankshaft main bearings
Usually a dull, metallic knock. It is detected when the throttle valve is opened sharply at idle. Its frequency increases with increasing crankshaft speed. Excessive axial clearance of the crankshaft causes a sharper knock with uneven intervals, especially noticeable with a smooth increase and decrease in crankshaft speed.
Knocking of connecting rod bearings
Usually the knock of connecting rod bearings is sharper than the knock of main bearings. It can be heard at idle speed of the engine when the throttle valve is opened sharply. The place of knocking is easy to determine by disconnecting the spark plugs one by one.
Knocking of pistons
This knock is usually muffled and quiet; is caused by the piston "beating" in the cylinder. It is best heard at low crankshaft speeds and under load.
Knocking of exhaust and intake valves
Operating with increased valve clearances causes a characteristic knocking sound, usually at regular intervals; its frequency is lower than any other knocking sound in the engine, since the valves are driven by the camshaft, the rotation frequency of which is half the rotation frequency of the crankshaft.
Excessive camshaft drive chain noise
From the general engine noise, the noise of the camshaft drive chain stands out when gaps appear between the engagement elements and is clearly audible at low crankshaft rotation speeds.
Insufficient oil pressure at idle with a warm engine
Excessive oil pressure on a warm engine
Oil pump relief valve sticking - Replace valve
Increased oil consumption
Increased fuel consumption
Engine overheating
Rapid drop in fluid level in expansion tank
