2000 cherokee 4.0 blah blah blah

Randomly the temp will sky rocket to red.
but it also goes from 0 to 210 really fast after a few miles.

The oil pressure reads from 40-60 psi, but it will randomly drop to nothing.


It overheated today, I think. I wasn't driving and it stalled out and wouldn't start until I took it to a garage and it started so I didn't have to push it in.

I pulled off the valve cover and torqed down the head bolts to 110-120lbs. It has a fresh head gasket and the bolts where at 80ish lbs when I went to tighten them again. I had them all above 100lbs last week. I think the heat did some work on them?

But what might cause the gauges to act so... spontaneous? heat went from 0-210 in 5 seconds and stayed for a good hour before going from 210 to red.

Oil pressure, I think, might just be the sending unit or the gauge? because why would it come back unless there is an air leak... and I doubt there is.





oh and it's running open headers but that should just make it run rich cause of the o2 sensors and a rougher idle

Any tips/tricks/ideas/theories... anything will help

Thank you.

 

Sorry to tell you this, but there is a pretty significant chance that the head is cracked. The 00-01 from the factory came with the 0331 cylinder head, which has a known casting defect between cylinders 3-4. An overheat almost guarantees a cracked head, and you have described some classic symptoms with yours.

I'm not going to get into detail here, but will provide a link to a thread that does. This thread is "required reading" for everyone with an 00-01 XJ.

http://www.jeepsunlimited.com/forums...d.php?t=391831

Let us know if you have any specific questions. Good luck!

 

Going through this myself, Ordered a replacement head from Clearwater Cylinder heads. It should be here this afternoon though! Same symptoms as everyone else, except the oil pressure problem, but I can see the crack in the head very easily just looking through the oil fill hole.