Any head can crack internally where you can't see it. Even magnafluxing might not show it.

It happened to me on my '92. Long expensive story.

 

hmmm:/ Well, if this proves to be the case, I'd probably make this engine into a stroker while i have it apart...

Was your oil funky on your 92? Any other signs of cracked head aside from coolant loss?

 

Here is the condensed version: Jeep needed radiator when I bought it. College kid said it ran hot. Radiator leaking.

Replaced, over time, trying to get temps down:

Radiator
Water pump
Thermostat, twice
Fan clutch
Electric fan
Fan shroud
Cracked exhaust manifold
Catalytic converter
Hoses
Thorough flushing more than once
Replaced leaking freeze plugs on the side of the block

Replaced head and head gasket, diagnosed as having cracks in #5 and #6 valve pocket. Put "good" used head with less miles on it.

Used head blew out the rear freeze plug. Replaced it with rubber plug, which blew out 3 times, losing all coolant real quickly.

Pulled that head because Jeep still running hot, only way to replace with metal plug was to pull head.

After head off, elected to pull rest of engine out and rebuild everything professionally. Head was magnafluxed and pronounced OK.

Jeep still ran hot after rebuild. Pulled head back off, had a different head rebuilt. Reinstalled everything. Now it runs nice and normal, even in 114 degree humid heat with A/C on, in traffic.

They never did find any cracks in that second head. I believe it was cracked internally where it could not be detected.

The oil never turned milky. The Jeep had lower than normal pressure while running, about 25 PSI and maybe 5 PSI at hot idle. Had about 40 PSI on startup. No telling how many times the kid overheated it.

All this stuff was done over a period of about 2 years. Not all at once. One after the other.

I was scared of it until I finally solved the overheating problem by total rebuild and a third head. No way would I have taken it out of town, with or without my family in it. It was not reliable.

 

Yes there is do all the simple test first b4 jumping feet first into major denairos...jm2cw...

 

Good news everyone! After checking compression, everything still seemed okay...I FINALLY found a leak in the upper radiator hose. It was only opening when the engine was hot and when it was open, it was just barely letting coolant seep onto the valve cover where it would quickly evaporate! When i ben t the line, it would open the hole and coolant would gush out! Replaced line, hoping to see no more coolant loss

 

What a relief!

Always keep an eye on the coolant level on your particular Jeep, just in case.

 

Simple 'noggin pokin' solves the issue, never underestimate it!

 

Fo sho! Will update after a little time!