I just bought a 2001 Cherokee with 58,000 miles on it. After a close inspection, hopefully not too late, I noticed that the head has been reworked - fresher black paint, new gaskets, new thermostat housing etc. So do you think my baby overheated and cracked a head sometime in the not too distant past? The repair didn't show up on the CARFAX report. How do I tell if my head was the "0331"?

 

not sure if a build sheet would show that

 

go here...http://www.jeep.com/wccsapp/universa...ull&category=U

 

What will this get me?

 

factory build sheet

 

I'm giving the factory build sheet a try. One question; Once the head is rebuilt, does the defect persist?

 

On the drivers side, near the valve cover, you will find the casting #, i.e 0331, 0630 etc. To answer your question if the defect is still there, it was was swapped for a another 99-02 0331 head, then yes. If it was swapped for a later 03+ 0331 "TUPY" head, which can be verified by looking in the oil filler hole with a good light and see aforementioned "TUPY", then no, or option C, if it was replaced with an aftermarket head, i.e Alabama Cylinder Head, or Clearwater Cylinder Head, then also no. Depending on who did the work, it may have not been reported to carfax.

 

head is garbage if cracked

 

i think hes asking if it came from factory with 0331 installed.

 

01's have 0331 head. My head appears to have been worked on or replaced. No problems so far but only 4.5 months in. Not worried about it though jeep runs just fine.

 

Gee what a surprise! CARFAX is a waste of time and money. If you notice in their ad they say they will show accidents, repairs ,etc "Reported to CARFAX". But guess what. Almost no body shop or repair shops or even a lot of insurance companies report things to CARFAX so none of those repairs or damages will show up on the report... I've run a lot of vehicles thru it which I know where in wrecks and they all came back clean. I even changed the milage 75,000 miles and it didn't show a problem.

 

Never rely on Carfax for the total story. Never. Sure, run it and see what it spits out, but don't become complacent and think that it tells 100% of the story.

All 2000 and 2001 XJs came from the factory with the 0331 cylinder head.

If yours was replaced, it is likely that it was cracked. Whether or not the crack was discovered quickly enough to resolve it BEFORE engine bearings were affected is the question.

The biggest indicator of an engine bearing problem is your oil pressure. The oil pressure spec for the 4.0 is as follows:

*Not less than 13 psi at hot idle
*Between 37-75 psi over 1600 rpms

How is your oil pressure?

 

I'll take a look after work - check for casting designation and a close oil pressure reading. The oil pressure seems about the same as my last 4.0 but I'll do the rev test and report back tonight.

 

Use a mechanical gauge to check oil pressure. Cluster gauge is not a true gauge and will read zero if pressure drops below 8psi. My jeep also had the same signs as yours, new head (still a 0331) and low oil pressure (5psi @idle). If it is not knocking I would not panic. Low oil pressure at idle will not harm an engine,it just indicates worn bearings. While this might sound serious the chances are in your favor that the coolant caused SOME wear in all of the bearings. This would have an accumulative effect on pressure but your bearing clearances could still be within the tolerance limits. I plan to drive mine easy until I get a chance to pull the pan and replace the bearings. A good way to verify this condition is to drain your oil into a clean drain pan and then examine the bottom of the pan after you pour the oil out. If you find (look close) silver or gold colored dust like flakes you probably have the glycol damage.

 

This is really great information, and I really appreciate it. I'd much rather know the whole, unvarnished truth than to try to kid myself but just so you know, YOU GUYS ARE SCARING THE CRAP OUT OF ME!