KCsurfer420 Posted March 22, 2011 Share Posted March 22, 2011 So i have a 88 jeep comanche. I bought the truck for 600.00 not running and have spent around 8000.oo on it to date. I installed a hisco 4.7 stroker and replaced every thing having to do with the cooling system ( I.E. water pump, both hoses, thermostat, CFS 3 cor copper radiator, hi flow thermostat housing and coolant sensor and guage coolant sensor.) now my problem is when i drive the truck it begins to get warm. I can get the truck to stay at about 230if i turn on the heater and it doesent get hot enughf to boil over but it definatly gets hot. If i don't turn on the heater it runs right at that last marc before the red. I just ordered a new zj HD fan clutch to see if that helps but i dout it will. Its weird because when its running hot if i turn the truck off i can touch the radiator and its hot on the top of it but at the bottom of the radiator it stays realy cool. I'm thinking that i have a colgged radiator som how. The electric fan is wired to a switch and i runn it all the time at this point to try and help the temp issue. The only thing that i don't have on the system is the heater bypass valve ( i got rid of it when i converted to the newer style rediator but i don't think that has any thing to do with my problem but hey it might) so should the radiator be warm from top to bottom or is it normal for the rradiator to have a variance of 30* or more from top to botom? I'm at witts end here and I'm looking for some good advice. I installed the radiator before installing the new motor and ran the old motor a few times with this radiator. when installing the new motor i flushed the heater cor and all kinds of nasty brown fluid came out wich leads me to belive that i may have clogged the new radiator since every thing else is new. I have checked and the thermostat is opening and closing like it should.... WTF do i do I want to wheel this thing but it doesent want me to........ Link to comment Share on other sites More sharing options...
maddzz1 Posted March 22, 2011 Share Posted March 22, 2011 Send a Pm to Don (hornbrod). He has the same engine engine in his MJ and I think he HAD cooling issues at first. Link to comment Share on other sites More sharing options...
Akula69 Posted March 23, 2011 Share Posted March 23, 2011 If you replaced the bottom radiator hose AND it does not have a spring in it to keep it from collapsing while the engine is running you will have the symptoms you described. Read here: viewtopic.php?f=2&t=25205&start=15 Link to comment Share on other sites More sharing options...
Exgrayxj Posted March 23, 2011 Share Posted March 23, 2011 I had somewhat the same problems with my XJ. Engine swap, LT1 chevy, had no heat and radiator still cool though engine over heated. Have you bled the air out of the system? Air pockets will stop flow. Also possible belt is run wrong through pulleys, pump turning wrong direction? I am an old mopar guy, these XJ/MJs are a new animal to me too. Good luck. :peek: Link to comment Share on other sites More sharing options...
Sir_Brando Posted March 23, 2011 Share Posted March 23, 2011 you said youve replaced everything in the cooling system but it sounds like a clogged radiator. my 97 zj was having the same issues shortly after replacing the radiator and hoses. i did a flush and it quit acting up and never overheated. somewhere somehow, something got into the system and was clogging it up. just my 2¢ :dunno: Link to comment Share on other sites More sharing options...
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