mystery coolant leak
#17
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Join Date: Apr 2011
Location: central PA
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Year: 2000
Model: Cherokee
Engine: 4.0
Was your oil funky on your 92? Any other signs of cracked head aside from coolant loss?
#18
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Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
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.
Last edited by Firestorm500; 05-11-2015 at 03:45 PM.
#20
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Year: 2000
Model: Cherokee
Engine: 4.0
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
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