Possible causes
Low oil or low oil pressure
With a low oil level or pressure, engine parts work with more friction. First check the level on the dipstick with the car on level ground. If the oil pressure warning light is on, do not start the engine.
Valve train and hydraulic lifters
A light, fast tick at the top of the engine when cold that disappears once warm is often related to the valve mechanism. The cause may be the oil or worn parts.
Crankshaft and connecting rod parts
A dull knock that grows with revs and load is a serious sign. Driving on can lead to an expensive engine repair. This kind of sound should be checked as soon as possible.
What to tell the mechanic
- When you hear it: only when cold, after warming up, at idle or when accelerating.
- Whether the sound changes with engine revs.
- Whether the oil pressure or engine warning lights came on and when the oil was last changed.
What you can do
If the knock is dull and loud, or appeared together with the oil pressure warning light, switch off the engine and do not drive on. Check the oil level. It is better to bring the car to the workshop on a tow truck.
Where the check starts
The mechanic finds the exact cause during the inspection.
Frequently asked questions
Can I drive if the knock disappears once the engine is warm?
That does not mean there is no fault. A light knock when cold should be shown to a mechanic soon, especially if it lasts longer or has become louder.
Will an oil change help?
If the oil is old or the level is low, a change and top-up are needed anyway. But worn parts do not recover after an oil change. The source of the noise has to be found first.