All,

I have a 96 XJ that overheats. In summary the shop detected exhaust gases in the coolant and suspects the head is cracked. It has about 250K miles on it. Would I be better off swapping the head or engine. I can get a good condition used engine from a wrecked 98 xj from the local JY with 109K miles for about $500. Or I could get a rebuilt or used head but haven't priced those yet.

Any advice is most appreciated

 

you can do compression test by yourself first to make sure it is indeed head gasket / head crack related.

my personal opinion is that it would be more trouble to swap in a "new" engine rather than replace the head, unless you have other engine troubles. clearwater heads are around 450-500$ with core return, i would go this route, if it indeed ends up being a cracked head.

 

Thanks for the feedback. Other than overheating, the only other engine issue is that sometimes it doesn't want to idle for a few minutes when first started for the day. Otherwise, it seems to run strong.

 

What is your OIL PRESSURE? Verifying this with a mechanical oil pressure gauge might be a good idea. The oil pressure spec for the 4.0 is 37-75 psi over 1600 rpms with no less than 13 psi at hot idle. If you have been burning coolant for more than a short period of time, that will damage the bearings in the engine and your oil pressure will start to drop.

Once you get to the point of diminishing oil pressure, swapping on a new head is not going to be a good option as it only fixes half your problem. A salvage yard engine would be a better option and with 250k on your engine, I'd probably opt for jumping on that 109k engine for $500. A new head is going to cost you close to that so swapping in a salvage yard engine seems to be a very good option to consider.

Good luck and keep us updated!

 

Are you sure its over heating?The 4.0 in these jeeps 210 degrees they are happy but some people are use to newer cars that run colder and think its overheating.

 

Thanks, TJ Walker, I'll check the oil pressure as well before I start disassembly.

 

Yes, it definitely runs hot. Guage goes into the red. Also, indicates a high temperature when connected to the OBDC connector. Do not recall the temp off hand though.