Engine Knocking at idle when cold

Hello,

I have a 1995 cherokee 6 cylinder with 153000 miles.
Recently I have notived a knocking noise when the engine is cold at idle.
I seems it comes from the top rear engine.
It sounds like a diesel sound and it is almost not noticeable when the engine is warm.
I changed the spark plug and did not fix the problem.

I hope it is not to bad.

Any suggestion about where this problem might coming from?

Thanks,

Hello,

I have a 1995 cherokee 6 cylinder with 153000 miles.
Recently I have notived a knocking noise when the engine is cold at idle.
I seems it comes from the top rear engine.
It sounds like a diesel sound and it is almost not noticeable when the engine is warm.
I changed the spark plug and did not fix the problem.

I hope it is not to bad.

Any suggestion about where this problem might coming from?

Thanks,

How about changing the oil and filter. Try a hi milage oil or 4x4 sythetic blend.

My Jeep had the same noise when I first bought it (used 85K).
I had a mechanic listen to it and he said it is Piston Slap. Usually it is caused by the cylinder being slightly out of round or the piston is slightly lopsided because carbon is built up more on one side than the other. Many different things can cause piston slap. I changed the oil to mobile one and within about 3000 miles the slapping sound went away, never to return. The Mechanic also said that because it had sat for a while waiting for Auction (Forest Service), it could have had a piece of sludge break off of the rings causing the problem. He said that he has heard Jeeps with all of the Cylinders slapping before, sounds like a Diesel engine but still runs fine.

I have used synthetic since 10k and now have 125k on it with no engine piston slap. However....other issues can be a prob........