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Poll: Cracked 0331 cylinder head castings

Could a blown gasket or cracked head cause my xj to overheat at highway speeds? I've changed just about everything on the cooling system and it has not made a difference. Once the temp gets over 210 the oil presure drops below 20 when idling. This has happened ever since it over heated when driving up a very long mountain road.

I noticed that the head number on my 97 is 0630 I'm guessing that is better than having the 0331.
 
Overheating on the highway is usually caused either by items obstructing airflow through the radiator (driving lights, winch, mud in radiator) or by insufficient coolant being able to flow through the radiator (blocked radiator core, collapsing lower radiator hose).
Oil pressure drops when the engine's hot because hot oil is thinner and flows more easily through bearing clearances.
 
XJ 12/99 213K miles - Cracked head

Oil pressure 40psi cold - 10psi warm
 
Last edited:
<sound of B movie screamer here>

Another ZOMBIE Thread back for Halloween!!!

'Quick Paw, Get out the Street Sweepers, we'z got us some Zombies to kill!"
 
I have 00xj i havent had that problem yet knock on wood. Aside from getting another head from a junkyard what would be other options? i know older heads dont have the mounts for the coil pack or is there a way around that?
 
I just hit 188,000 miles on my 2000 XJ and I have no coolant in the oil. I take a UOA at every oil change.
 
I just bought my first xj a few weeks ago with a difficult-to-diagnose cracked head. Build date of may, 2001. 180k. Oil looked good. Coolant looked good. No smoking tailpipe. Good oil pressure. Had a mechanic look at it before buying. He said the head looked good.

Put 500 miles on it and noticed the coolant in the reservoir had gone down. Dammit. Made a video with my iPhone in the oil fill hole with the engine running and there it was - coolant seeping out of a hairline crack.

My local guy, who is a former jeep dealer, quoted me $1300. Sounds good to me.
 
Gonna try to post a video

IMG_3736.mp4.html
 
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