ok my jeep (2001 XJ 4.0) is making a loud **** ticking/clunking noise (sounds like the loudest exhaust leak ever). I took it to a local shop and told them to diagnose it(told them i wanted to keep it cheep), they basically started it and told me from the noise they heard it was a spun main bearing.

I am totally lost, i dont think spun bearing because i lost no oil pressure. I am just looking for some advice before i tear this thing apart, as in things to look for/try.

The heep has 115,*** miles and i just had the motor out 4 months ago to change cam and cam bearings. When i had it out the cylinder walls had no ridge at all and the most clearance i had on a main bearing was .001,

 

sounds like a bearing is gone to me, you'd be safe to just tear it down and replace the crank bearings, maybe just a good rebuild is an idea.

 

oh i forgot about the two codes i got at autozone on their scanner a couple days befor, they were very small evap leak and very large evap leak.

 

just curious, did you check the exhaust manifold for a huge crack?

 

Use a long screwdriver and put the tip on the block near the bearing journals. Hold it with your hand near the top of the handle, and put your ear on your hand. If it is a spun bearing you should be able to isolate it. I know it sounds silly, but it works, you'd be amazed what you can hear in you engine with this method!! HTH!!

 

no i havent checked the manifold yet that will be one of the first things i do and i will try that COS thanks

 

I had the same noise on a 97 xj i just bought (has 70k on it).

First if you have a vacuum leak, it can cause you to run lean, causing detonation, which is what happened in mine. The noise was caused by a cracked piston. Does it run on all cylinders?
As far as cheap goes, it took me a couple weekends but i changed the piston, all of the rings and bearings, plus had the head completely gone through for 600 bucks (including gaskets, etc.).