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  #1  
Old July 25th, 2014, 21:08
88_xj_ 88_xj_ is offline
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Overheating issues!?

I have an 88 xj 4.0 it is having some over heating issues while driving around town if i keep the rpms under 3000 then the motor runs fine and the temperature is at normal temp. But anytime i rev it past 3000 like if i take off pretty hard the temp starts to rise pretty fast. Im wondering if anyone knows y this is happening
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  #2  
Old July 26th, 2014, 07:07
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87manche 87manche is offline
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Re: Overheating issues!?

stock cooling system?

toss it in the trash, spend $300 and swap it to the open system with new hoses/pump/thermostat.

enjoy not messing with it for the next 5 years.
serious. If you've still got stock 27 year old parts in there it's just time to wholesale replace the system.
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  #3  
Old July 26th, 2014, 19:40
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88trailcrawler 88trailcrawler is offline
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Re: Overheating issues!?

Closed system can work just fine as long as everything is in proper order.

Agreed that if your running 27 year old stuff a lot of it is due for replacement.

Hard to suggest a starting point not knowing any history. Check for leaks. Check the bottle and cap. Pressure loss will result in increased temps.

Good news is even a complete cooling system replacement (radiator, hoses, water pump, t-stat, bottle and cap) isn't too terrible of a project. Even if you include the fan clutch.

Check for leaks, coolant smell and bottle expansion then repost.
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  #4  
Old July 26th, 2014, 22:40
88_xj_ 88_xj_ is offline
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Re: Overheating issues!?

Ive just recently replaced the water pump. Next im gonna put a new thermostat in and see if that works. Thanks for the advise
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  #5  
Old July 27th, 2014, 08:44
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87manche 87manche is offline
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Re: Overheating issues!?

Quote:
Originally Posted by 88trailcrawler View Post
Closed system can work just fine as long as everything is in proper order.
.
it can, the problem is keeping it in proper working order.

I prefer to just swap it, then you don't deal with it ever again.
Radiator for a 91 has the threaded port for the renix fan temp sender and is cheaper and much more available than the closed system part.

drops in. Use generic autozone $8 coolant catch tank and you're done. Take you like 2 hours. I've got radiator swaps down to 30 minutes these days. Three this year....
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  #6  
Old July 29th, 2014, 10:37
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sidriptide sidriptide is offline
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Re: Overheating issues!?

how much time are you spending over 3000 RPM ?? the 4.0L can certainly handle it, but it seems like you're winding out the RPM, and hard acceleration or sustained high RPM in lower gears will absolutely show you if your cooling system is not up to the task.
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  #7  
Old July 30th, 2014, 07:35
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yossarian19 yossarian19 is offline
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Re: Overheating issues!?

There are a bunch of things that could be causing this.
Old, clogged radiator
Weak fan clutch
Lower hose collapsing down and restricting flow under suction
Cracked head
stuck / lazy thermostat
etc.
What color is your coolant? Everything clean in there?
When you shut off the engine, does the fan keep moving for a few spins or does it stop pretty quickly?
Have you done any maintenance on the beast? Fresh water pump, etc?
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  #8  
Old July 30th, 2014, 07:40
CompleteCherokee CompleteCherokee is offline
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Re: Overheating issues!?

did you replace the water pump due to the overheating? Or did the overheating start after you replaced the pump?
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  #9  
Old July 30th, 2014, 13:02
88_xj_ 88_xj_ is offline
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Re: Overheating issues!?

The belt broke a little and when it did it wrapped around the fan causing the fan to not spin. And the waterpump is new. I replaced it because it was the original and was in pretty bad shape. I drained the cooling system and put new coolant. And it did not over heat before. I dont let it get to where it is actually over heating but it does get up to about 250. Im pretty sure the thermostat is sticking either that or my temp gauge is not working. Because the gauge will say its at about 210 or so and then it will drop down all of the sudden to about 150-170and then back up to 210.
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  #10  
Old July 31st, 2014, 06:00
CompleteCherokee CompleteCherokee is offline
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Re: Overheating issues!?

the dropping down is probably the thermostat opening, and once it drops below the rating for the thermostat, it climbs back up. What is the rating of your thermostat?
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  #11  
Old July 31st, 2014, 12:17
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Re: Overheating issues!?

Quote:
Originally Posted by 88_xj_
Because the gauge will say its at about 210 or so and then it will drop down all of the sudden to about 150-170and then back up to 210.
Sounds like you have an air pocket.
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  #12  
Old July 31st, 2014, 13:46
scottmcneal scottmcneal is offline
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Re: Overheating issues!?

What he said, need to burp it.
I have a closed system in my 89 and run with the AC on while off roading, does not over heat after i had the system done by a shop. A professional radiator shop does a better job than the crap you get in the parts house.

Today is a cool day, only 110 and i can run all day with the AC on.yes even when it is 120 out.
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  #13  
Old July 31st, 2014, 13:46
CompleteCherokee CompleteCherokee is offline
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Re: Overheating issues!?

did you burp the system a few times, and run the heater while burping?
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  #14  
Old August 1st, 2014, 14:29
88_xj_ 88_xj_ is offline
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Re: Overheating issues!?

I havent tried burping it. Ill give that a try
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  #15  
Old August 2nd, 2014, 06:31
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cruiser54 cruiser54 is offline
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Re: Overheating issues!?

REplace the crappy cap on the coolant bottle with a 703-1396 from Napa first chance you get also.
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