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Running out of ideas on overheating

ehall said:
First thing is get an infrared temperature gun and measure heat at the thermostat housing. The senders and sensors are pretty unreliable.
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This. After verifying temp and seeeing temp change when tstat open/close, my ICP gauge shows ~10 deg. higher than what it is.
 
Quick note about the water wetter additives. I think the effect is minimal when running 50/50.

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Eeyore said:
I might have missed it, but did the rebuild include a new fan clutch?

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Yep on my second ZJ fan clutch from Napa. First one was from eBay with a napa part number. After swapping out everything else I figured the eBay clutch might not be working properly. Now I have two clutch fans, 2 water pumps, a spare radiator, ton of thermostats and a bunch of other spare parts. Going to give the Mopar radiator a shot after the IR temp light. Ordered one a few days ago to test my fuel injectors.
 
SBpunk said:
For the HO is right on the thermostat housing. I drilled a small hole in the 12 o'clock position to help the air get out. Elevated the front driver side to get the fill tube to the highest point. Ran it to temp a few times using a no spill funnel 1/2 filled with fluid. Kept doing that until the bubbles stopped. Was a pain but if theirs still in air bubble in there its going to take a small miracle to get it out. I shook the jeep around a bit too while it was going to try and dislodge any stubborn ones.
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later HO's used the engine temp sensor on the thermostat housing for both PCM and instrument cluster. early HO's had 2 the instrument cluster has its own sender on the rear of the head on the drivers side. has one wire coming off the top of it. they tend to trap air in that area. if you can get the rear of the jeep on ramps wait for the engine to cool down and remove the sensor ever so slightly to bleed the air. watch out its going to want to push that sensor out.
 
I had three major contributing factors to my highway temperature problems. One is the overdrive clutch packs are worn out so the trans was slipping on the highway but not in town. I also had a crack in the exhaust manifold that was letting air into the exhaust above the O2 sensor, making the computer think the mix was lean, so it was dumping fuel causing the cat to run super hot. Then I went through a couple of holes and sucked water into the exhaust, and clogging up the cat.

Replaced the exhaust, replaced the cat, and driving in 3rd
 
Exhaust is still brand new. I haven't had it checked for leaks at the block but it sounds sealed up. No obvious air flow either. Same with the connecting downpipe. Manual trans with fresh oil as well. I tried to order a Mopar radiator but looks like it's going to be a pain in the ass. Both places I've ordered from gave canceled within two days.
 
I'd worry more about the condenser in front of the radiator blocking air flow than trying to find a mopar radiator. Unless you've got a particularly defective aftermarket radiator I don't think mopar radiator will solve the issue. If the fuel mixture and exhaust are correct and the problem is in the cooling system then maybe it'd be worth swapping out the radiator again. I'm still puzzled how it was working fine before the rebuild to suddenly have trouble.






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90xj06 said:
later HO's used the engine temp sensor on the thermostat housing for both PCM and instrument cluster. early HO's had 2 the instrument cluster has its own sender on the rear of the head on the drivers side. has one wire coming off the top of it. they tend to trap air in that area. if you can get the rear of the jeep on ramps wait for the engine to cool down and remove the sensor ever so slightly to bleed the air. watch out its going to want to push that sensor out.
Click to expand...



Good tip. May use it next time I have to mess with the cooling system .


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So last ditch effort (aside from a plastic mopar radiator) is this 195 mopar thermostat and bleeding the back of the system. The mopar thermostat came with some weird valve thing on it. I've heard to just remove it so the hole is always open at the 12 oclock position. Good or not so much? Damn thing cost me 33 bucks so apparently its made from gold and unicorn marrow. Going to test it before installing with an IR gun and a pot of water. Oh and going to take it down and get the system pressure tested after its installed just to make sure I'm not crazy and theres some invisible leak I'm not seeing.
 
Did someone leave a shop rag in the motor when they "rebuilt" it? Working at Chrysler/Jeep/Dodge for 11 years and I have seen this twice...

Just a thought.
 
Nealio240z said:
Did someone leave a shop rag in the motor when they "rebuilt" it? Working at Chrysler/Jeep/Dodge for 11 years and I have seen this twice...

Just a thought.
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.... I.... I'm not even sure how to respond to that lol. Any tips on locating or checking for it?
 
SBpunk said:
.... I.... I'm not even sure how to respond to that lol. Any tips on locating or checking for it?
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There really isnt a way to accidentaly leave a shop rag in the water ports. Now a freeze plug or 2 knock in and not pulled out before the new ones are installed is a better possibility
 
ehall said:
Did you verify / eliminate the overflow? Should see the bottle level rise after turning off the engine, then drop back down again when engine is restarted
Click to expand...

I blew air back into it to try and clear up any clogging. Also marked the spot where the coolant was sitting. No change at high or low temps. Even when I ran it up to 230. Ordered a new bottle and IR temp gun. Going to flush the system, add the mopar 195 t-stat, new recovery bottle, new rear sensor, backflow the heater core and bleed the system out. Might just add a new hose for the recovery tank anyway.
 
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