Author Topic: Overheating issues: FINAL UPDATE.  (Read 2044 times)

Offline XJBayne

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Overheating issues: FINAL UPDATE.
« on: July 26, 2020, 08:44:24 PM »
Been having overheating issues with my 98 XJ, now let me Tarentino it to the beginning...

I first noticed the heat in my XJ was very weak, then that the coolant in my overflow and inside the rad cap was a nasty brownish green color.  So I took it upon myself to clean it out and swap the fluid out and clean it the best I could. I was glad I did, I pulled out so much dirt, sludge, and crap. Here’s where the problems began. 

It started with a small amount of coolant bubbling out the overflow after shutting off the car. It slowly progressed to some kind of blowout under the hood, coolant shot out of the cap and overflow reservoir.  It went from the notch above middle to maxed out instantly.  Was able to fill it back up after cooling down and ran with the heat on back home.  I replaced the radiator cap at this point.  Then I had a shop run a coolant flush with BG additives in it and after that I swapped the thermostat.  Same issue today on my test drive.  Now coolant was also coming out of one of the heater core hoses. 

The system worked perfectly before I attempted to clean it out.  I did a block test with the blue block tester liquid.  It stayed blue and I wasn’t able to suck any more, the squeeze ball stayed deflated.  Think my radiator is all clogged up and can’t circulate properly? Or what else do you guys think could be causing it?  I’m not convinced its the water pump since it won’t overheat just sitting at an idle, its only under load with the AC going.

Appreciate any help, advice, and ideas!
« Last Edit: June 10, 2021, 05:48:28 PM by XJBayne »
98 XJ

Offline RFH_98TJ

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Re: Overheating issues
« Reply #1 on: July 27, 2020, 08:12:13 AM »
A 98 XJ.  You potentially have a 22 year old radiator and water pump.  I would think it is probably time for a new radiator.  If it was me, I'd do a new pump at the same time too.  The sucky part is, if its never been done, you may break a bolt or two off doing it.  That brown liquid could have been the rusted pump fins.  If they are worn down, it may not be moving enough coolant at high rpm.  I would definitely change all the hoses while you're in there too unless you know they're age.  Not knowing what you put in, make sure you have a 195 degree thermostat.
98 TJ 4.0 Sport 5-speed - 4" lift on 35s, 4.56 on D30 with Lock Right and Ford 8.8 LS, Lots of welding

- Frank

Offline XJBayne

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Re: Overheating issues
« Reply #2 on: July 27, 2020, 09:07:33 AM »
A 98 XJ.  You potentially have a 22 year old radiator and water pump.  I would think it is probably time for a new radiator.  If it was me, I'd do a new pump at the same time too.  The sucky part is, if its never been done, you may break a bolt or two off doing it.  That brown liquid could have been the rusted pump fins.  If they are worn down, it may not be moving enough coolant at high rpm.  I would definitely change all the hoses while you're in there too unless you know they're age.  Not knowing what you put in, make sure you have a 195 degree thermostat.
I think you’re right.  I spent every bit of the evening on YouTube and ran across a video with the exact same situation as me, and it was the water pump. 

The previous owner had claimed he flushed the system and replaced all the cooling parts in June of last year.  If he mixed his coolant with tap water like I suspect he did based off of the color and junk I pulled out, who knows what the new parts look like.  So I’m gonna do a new pump, new radiator, and new hoses like you suggested. May as well since I’m there. The thermostat i put in was a Stant 195.

This guy had used a front driveshaft in the rear, let his steering bomb, etc, and drove it like that. Don’t think this guy was the smartest.
98 XJ

Offline dave2002ti

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Re: Overheating issues
« Reply #3 on: July 27, 2020, 09:23:40 AM »
You might try Redline Waterwetter to give you little time until you can change the radiator and pump.  Might also want to consider using it if your stock cooling system is marginal even when all new.

See http://redlineoil.com

Dont forget to consider repalcing all your hoses and checking the condition on your heater core.

Dave Apker

Offline XJBayne

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Re: Overheating issues
« Reply #4 on: July 27, 2020, 09:36:55 AM »
You might try Redline Waterwetter to give you little time until you can change the radiator and pump.  Might also want to consider using it if your stock cooling system is marginal even when all new.

See http://redlineoil.com

Dont forget to consider repalcing all your hoses and checking the condition on your heater core.

Dave Apker
I have plenty of other vehicles so it won’t be moving until the parts arrive, but I’ll keep it in mind for later.  I back flushed all kind of junk out of my heater core.  One of the reasons why I started fooling with the cooling system was because of my lack of heat.  After the flush, I’ve had crazy hot heat, but it’s something I’m gonna keep my eye on for sure.
98 XJ

Offline dave2002ti

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Re: Overheating issues
« Reply #5 on: July 27, 2020, 06:35:49 PM »
Get a hot plate and fill a pan with water and let it boil. Remove temp sensor from block and drop in pot and read your temp gauge.  Cheap way of finding out how accurate everything is.

Dave Apker

Offline XJBayne

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Re: Overheating issues
« Reply #6 on: August 23, 2020, 10:15:53 PM »
Update:  cooling system is entirely new, been flushed twice now.  Still overheating on the highway under heavy load.  I have to run the heat to keep it from overheating.  Guess that means a cracked head or blown head gasket.  Anyone recommend any shops in the area?
98 XJ

Offline wbsjp

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Re: Overheating issues
« Reply #7 on: September 01, 2020, 03:54:40 PM »
Have you replaced the fan clutch ? NAPA has a HD unit that works well, it fits close to the rad, but does not hit it unless the motor mounts are bad.  #272310 fits a 97>98 ZJ
Wayne
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"the cost of Freedom isn,t Free"

Offline dave2002ti

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Re: Overheating issues
« Reply #8 on: September 01, 2020, 05:10:08 PM »
Update:  cooling system is entirely new, been flushed twice now.  Still overheating on the highway under heavy load.  I have to run the heat to keep it from overheating.  Guess that means a cracked head or blown head gasket.  Anyone recommend any shops in the area?

Redline Water Wetter.   And second checking the fan clutch.  What is the condition of the fan?

Dave Apker

Offline wbsjp

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Re: Overheating issues
« Reply #9 on: September 02, 2020, 09:44:40 AM »
Another thing to check,,,,,does the aux electric fan cycle on with the AC running ? It should ,some years it fan would run anytime the AC was on.Other years the fan would cycle when the AC would cycle.
Wayne
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"the cost of Freedom isn,t Free"

Offline R3

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Re: Overheating issues
« Reply #10 on: September 02, 2020, 12:11:18 PM »
Update:  cooling system is entirely new, been flushed twice now.  Still overheating on the highway under heavy load.  I have to run the heat to keep it from overheating.  Guess that means a cracked head or blown head gasket.  Anyone recommend any shops in the area?


Check oil and coolant.  If  coolant in the oil  suspect either head or gasket.

Check  tail pipe for coolant smell. suspect cracked head.

Check plugs... very clean one indicates  the presence of coolant

Do you have a fan shroud? no = overheating issues

Fan clutch, working properly?

Fan HD fan or electric fan setup might solve  "heavy loading" overheat problems.

Just thoughts
Cheers

17 JKURR Daily/rock crawler/overland
2013 Victory XCT hot rod.

Offline XJBayne

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Re: Overheating issues
« Reply #11 on: September 10, 2020, 08:34:35 PM »
I’ve read everyone’s responses.  Sorry for the delay, its been at another shop.

As far as the fans go, I originally took it took it OCD in Stafford and they confirmed both of my fans are good and operating properly. My aux electric fan runs when the AC is on or when engine is warm.

A second shop flushed it again and ran a pressure test on the system.  Everything checked out.

There’s no oil in the coolant and vice versa.  I haven’t smelt the tail pipe yet nor pulled the plugs but I’ll give it a shot.

A third shop found the catalytic converter was blocked so I replaced that.  I also put hood spacers on as a cheap way for right now to pull heat out of the bay.

Today I had to run up to Fair Lakes which is about an hour round trip.  Made it up no problem, running the notch to the right of 210.  Definitely toasty but the gauge never spiked.  I shut the car off and I cycled the key again a few moments after and the gauge was spiked.  Came out of the store and it was fine.  On the way back about half way home, the gauge spiked to red and I pulled over and shut the engine off.  I still had all my coolant and it was steaming a little.  5 mins later it was back to where it was running all trip.

So now I’m thinking to try and swap out the coolant temp sensor.

Is there any possibility one of the AC components could be overheating the engine?

98 XJ

Offline mopar31898

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Re: Overheating issues
« Reply #12 on: September 10, 2020, 10:31:18 PM »
I saw something the other day talking about how the harmonic balances can wear out on the 4.0 causing the belt to slip and not turn the water pump properly. I guess the pulley can separate from the weighted part of the balancer.

Try googling it and maybe take a look at yours. It seems like everything else is new so maybe this is something to check if it is original.


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Offline sjalkian

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Re: Overheating issues
« Reply #13 on: September 11, 2020, 08:02:34 AM »
It sounds like either a faulty sensor or a faulty gauge. It’s weird for it to spike like that.


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Offline XJBayne

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Re: Overheating issues
« Reply #14 on: September 11, 2020, 07:42:02 PM »
I saw something the other day talking about how the harmonic balances can wear out on the 4.0 causing the belt to slip and not turn the water pump properly. I guess the pulley can separate from the weighted part of the balancer.

Try googling it and maybe take a look at yours. It seems like everything else is new so maybe this is something to check if it is original.


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I saw that on YouTube, I could swear I tried mine out and I couldn’t spin it freely when I had the belt off doing my water pump, but I may try again.

It sounds like either a faulty sensor or a faulty gauge. It’s weird for it to spike like that.


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I agree.  Those are the next to swap out.  I did read on a old NAXJA post that there is something programed into the PCM that if a critical temperature is read by the sensor, it’ll spike the gauge and light the check gauges light to get your attention and to have you stop before damage is done.  But those parts are on order now.
98 XJ

 

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