cylinder knock?

My 97 XJ has a knock, and it sounds like it is coming from the top of the engine, and sounds like it is only one cylinder near the back of the valve cover, like the second to last cylinder is knocking on every cycle... At least this is what my mind is imagining it is hearing. It is definitely only coming from one specific cylinder and is in full sync with RPM, but never gets louder or softer, just a steady semi quiet knock that is out of place considering the rest of the engine is purring. Oil pressure is perfect, truck runs perfect. Any clues?

I have never been in a 4.0 jeep (Cherokee, Grand cherokee, Wrangler) That did not Knock, The worst was a 1994 Grand Cherokee, I Purchased it Brand new, It knocked from when it had around 12K (I sold it to a buddy @ 80k, He still uses it as his DD) & still knocks with 160K on the Odo.

is this your OCD kicking in again.

maybe a misfire, have you checked the condition of the spark plug compared to the others? plugs? have you checked for a bad spark plug wire?

89xj said:

is this your OCD kicking in again.

maybe a misfire, have you checked the condition of the spark plug compared to the others? plugs? have you checked for a bad spark plug wire?

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Damn! I am developing a reputation!!! I want to pick up a tester to test spark... I suspect weak spark or misfire, but I thought that would throw a code... OCD? Yes... Maybe why that damn knock bothers me so much... It does not sound severe in any case, but it is definitely out of place.

xj88superjeep said:

Oil pressure is perfect, truck runs perfect. Any clues?

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xj88superjeep said:

Damn! I am developing a reputation!!! I want to pick up a tester to test spark... I suspect weak spark or misfire, but I thought that would throw a code... OCD? Yes... Maybe why that damn knock bothers me so much... It does not sound severe in any case, but it is definitely out of place.

Click to expand...

are you just looking for problems or something to do?

No, I actually want to address it before it becomes an issue!