richardN
NAXJA Forum User
- Location
- Pennsylvania
Hello all, This is my first post here. I have read this forum for years but have only now had a reason to post. Yes my xj is overheating and , yes I have looked to find threads on the topic. But please read and you will agree there is no other problem like this one. I have worked on cars for over 20 years , from soup to nuts and even ran a little shop out of my garage. I have never been this stumped. Read on:
I have a 1996 Cherokee 4.0. It ran great coolant never went above 210 except on the hottest days ( high 90s- 100) Then maybe 220ish .
In 2019 the engine broke a piston. I replaced the engine with a rebuilt unit from ATK and at the same time had the trans rebuilt as it had 210,000 miles on it. I replaced the engine and at the same time put on a banks header and flow kooler waterpump and a all metal radiator from quadratec I forget the brand , CSF of something like that. All the other parts were stock. This was in OCT so temps outside were cool. Everything was fine (210 temps) until april 2020 when the weather was getting warmer. The temp would easily reach 230 or higher.
Long story short, I replaced that engine again with another one, thinking that perhaps there was something wrong causing the overheating.
After I replaced the engine Nothing changed(still running hot) So I tried a new Factory style radiator with the plastic ends , 160 themostat, 180 , and 195 , Factory waterpump , flow kooler waterpump, and all the combinations of these parts. Nothing made a difference. And this was with the new engine. I tried burping the cooling system to eliminate air bubles, new rad cap. Nothing changed. SOOOOO...... I replaced the ENGINE AGAIN!!!! after 2 months of fooling with this thing. Oh I also did a chemical test to check for hydrocarbons in the coolant, none found.
Onto the third engine, I guess it was July of 2020 at this point. I put the engine in and like clockwork it was running hot. I verified this using a scan tool and it easily was running at 235 just idling after driving it for a while. It seemed , if you could run at highway speeds it would run at 210 ish but if you start and stop it would shoot right up. I disconnected the exhaust and ran a down pipe to eliminate the cat just in case it was clogged. No change. I replaced the fuel injectors , No Change , I replaced the ECU , No Change.
Then the cooler fall weather came. It ran great . wouldnt go above 210 no matter what. That Brings us to now.
Running hotter than ever. Let me retrace my steps . (how many times can I do this) I put in a Mishimoto aluminum radiator, Put in their 3 fan setup, (I had previously had the factory fan and replaced the clutch)Flushed the system forward and backward , I didnt find anything surprising there. Put an external trans cooler with temp gauge, no trans fluid goes through the rad. Good trans temps. Ac works great. Replaced both temp sensors. still seeing temps 230-240 then I shut the car off. I even wrapped the banks header to try to keep under hood temps down.
Like I said If I could keep moving It seems like it would be ok but any stop and go or even worse idling it overheats.
I am not thrilled with the cooling of the radiator . If I check the top and bottom hose temp with a IR gun , there is only a 10-12 deg difference. I feel like it should be more.
I believe the gauge. because the scan tool backs it up and that uses a different sensor and when it shows 240 , it runs sluggish, you can tell its hot.
I believe the head gasket to be ok because of the chem test I did.
At this point its hard to believe that 3 engines would be bad.
As a rule of thumb , If its nice enough to put down the windows , it will run hot
I feel like all the factory stuff is good enough to keep thing cool, after all they made millions of these and they work just fine. But I have upgraded and replaced things because I thought it would help.
I am at a loss I am out of ideas . please chime in. Thanks
I have a 1996 Cherokee 4.0. It ran great coolant never went above 210 except on the hottest days ( high 90s- 100) Then maybe 220ish .
In 2019 the engine broke a piston. I replaced the engine with a rebuilt unit from ATK and at the same time had the trans rebuilt as it had 210,000 miles on it. I replaced the engine and at the same time put on a banks header and flow kooler waterpump and a all metal radiator from quadratec I forget the brand , CSF of something like that. All the other parts were stock. This was in OCT so temps outside were cool. Everything was fine (210 temps) until april 2020 when the weather was getting warmer. The temp would easily reach 230 or higher.
Long story short, I replaced that engine again with another one, thinking that perhaps there was something wrong causing the overheating.
After I replaced the engine Nothing changed(still running hot) So I tried a new Factory style radiator with the plastic ends , 160 themostat, 180 , and 195 , Factory waterpump , flow kooler waterpump, and all the combinations of these parts. Nothing made a difference. And this was with the new engine. I tried burping the cooling system to eliminate air bubles, new rad cap. Nothing changed. SOOOOO...... I replaced the ENGINE AGAIN!!!! after 2 months of fooling with this thing. Oh I also did a chemical test to check for hydrocarbons in the coolant, none found.
Onto the third engine, I guess it was July of 2020 at this point. I put the engine in and like clockwork it was running hot. I verified this using a scan tool and it easily was running at 235 just idling after driving it for a while. It seemed , if you could run at highway speeds it would run at 210 ish but if you start and stop it would shoot right up. I disconnected the exhaust and ran a down pipe to eliminate the cat just in case it was clogged. No change. I replaced the fuel injectors , No Change , I replaced the ECU , No Change.
Then the cooler fall weather came. It ran great . wouldnt go above 210 no matter what. That Brings us to now.
Running hotter than ever. Let me retrace my steps . (how many times can I do this) I put in a Mishimoto aluminum radiator, Put in their 3 fan setup, (I had previously had the factory fan and replaced the clutch)Flushed the system forward and backward , I didnt find anything surprising there. Put an external trans cooler with temp gauge, no trans fluid goes through the rad. Good trans temps. Ac works great. Replaced both temp sensors. still seeing temps 230-240 then I shut the car off. I even wrapped the banks header to try to keep under hood temps down.
Like I said If I could keep moving It seems like it would be ok but any stop and go or even worse idling it overheats.
I am not thrilled with the cooling of the radiator . If I check the top and bottom hose temp with a IR gun , there is only a 10-12 deg difference. I feel like it should be more.
I believe the gauge. because the scan tool backs it up and that uses a different sensor and when it shows 240 , it runs sluggish, you can tell its hot.
I believe the head gasket to be ok because of the chem test I did.
At this point its hard to believe that 3 engines would be bad.
As a rule of thumb , If its nice enough to put down the windows , it will run hot
I feel like all the factory stuff is good enough to keep thing cool, after all they made millions of these and they work just fine. But I have upgraded and replaced things because I thought it would help.
I am at a loss I am out of ideas . please chime in. Thanks