Recently noticed a faint knocking noise coming from the left hand side of the engine as you look at it from the front. Put my head near the cams and revved it a little and it knocked but then stopped as it revved higher.
My car is an MY98 and at first I thought piston slap but then I'm not a mechanic. My friend who is very good with cars said it might be a hydraulic tappet making the noise as it due an oil change which will be sorted next week.
Any advice would be great as of course, we all worry!

Dave

 

tappets usually tick and increase in frequency with revs..

could be a camshaft bearing..

 

M98 didn't have hydraulic tappets

Could be the injectors clicking away

 

Thanks guys, think you could be right with the injectors, think I'm a bit paranoid cos it's due a service and you hear every little rattle!!

Dave

 

easiest way to tell..

rev the engine and when you lift off the injectors shut and therefore stop clicking / ticking.. if it continues and slows with the engine speed then it is something else.

 

Is it a slow knock i.e alot slower then the crank or cam rotation speed. If so it may be the timing belt snagging on one of the guides.

I just had to have mine re-fitted after it was catching on the guide above the top left camshaft.

It causes the belt to flick up and hit the cover.
I think you can feel it if you put your hand on the cover in that area.

My local mechanic sorted it, and apparently after talking to a Subaru techie it is a common problem.

Solution is to move the guide slighty as they are on slotted mountings.