My Jeep is Overheating at Idle

[Lubener]

Bent, plugged fins on radiator, condenser or fan issues. Damaged or missing shroud? You have an airflow issue. A waterflow issue such as a waterpump would act up more at higher speeds such as highway driving. I am curious as to why the annual upper hose replacement?

 

[billt460]

Originally Posted by Miller88
......My last off road trip I noticed that when it started to heat up, I had no heat coming out of the vents. Once I bumped up the idle I got heat and the temperature dropped down again......

It sounds like the coolant pump isn't pushing enough coolant through the system at low idle. That would be the first thing I would look at. It's 7 years old, and may be starting to go.

 

[jeepman3071]

Originally Posted by Nick1994
I'm betting on the 0331 head.

Often times it cracks right under the oil cap.



That would cause milky oil and dark coolant, but not overheating. Low oil pressure also if the bearings get worn enough from coolant contamination.

My bet is on the water pump, sounds like it isn't pushing enough coolant especially at idle where I find the XJ system is the weakest at cooling. If your fans are working and the radiator is clean, it is a coolant flow problem.

 

[vwmaniaman]

No heat out the vents usually means that the water lines to the heater core are on the wrong pipes. switch the lines and test it again.

 

[atikovi]

Originally Posted by Mad_Hatter
Before throwing any more parts at it I'd get both the engine and cooling system compression tested.


What's the cooling system compression test?

 

[MarkM66]

Originally Posted by atikovi
Originally Posted by Mad_Hatter
Before throwing any more parts at it I'd get both the engine and cooling system compression tested.


What's the cooling system compression test?

 

[atikovi]

Originally Posted by MarkM66
Originally Posted by atikovi
Originally Posted by Mad_Hatter
Before throwing any more parts at it I'd get both the engine and cooling system compression tested.


What's the cooling system compression test?

Umm, that's a pressure tester.

 

[MarkM66]

Originally Posted by atikovi
Originally Posted by MarkM66
Originally Posted by atikovi
Originally Posted by Mad_Hatter
Before throwing any more parts at it I'd get both the engine and cooling system compression tested.


What's the cooling system compression test?

Umm, that's a pressure tester.


Umm. Pretty sure that's what he meant. Or do a leak-down test.

 

[WyrTwister]

Saw a South Main Auto video where the coolant pump was not pumping . Overheating . Think it was a Jeep .

Eric O. guessed the impeller was defective , but did not know if the impeller was metal or plastic . When he removed the pump , the impeller was spinning on the shaft , IE , no pumping . He whacked the impeller ( and pump ) flat on his work bench & the impeller tightened up .

Of course , he said he could not warranty how much longer it would work , so he installed a new pump .

I have seen videos of metal impellers that were so corroded , they would not pump coolant . Often the rest of the cooling system is a neglected mess .

Shot in the dark . Sounds like you have a mechanical fan . Is the belt and pulleys OK ?

I too wonder why you have had to replace a radiator hose multiple times ?

You said you had replaced the tstat ? Is there a " vent " to burp the air out of the system ?

Best of luck to you ,

 

[Donald]

Pump or fan.

 

[bullwinkle]

I have a similar problem with the XJ in my sig, the 1 row radiator just isn't big enough, going to go to a 3 row aluminum one. New water pump,coolant flush, & t-stat didn't help much.

 

[Mad_Hatter]

Originally Posted by MarkM66

Umm. Pretty sure that's what he meant. Or do a leak-down test.

Yes, thank you for fixing my mess up.ðŸ‘

 

[jeepman3071]

Originally Posted by bullwinkle
I have a similar problem with the XJ in my sig, the 1 row radiator just isn't big enough, going to go to a 3 row aluminum one. New water pump,coolant flush, & t-stat didn't help much.


Yup my 2000 always ran a bit warm until I did the following:

-3 row CSF radiator
-new OEM water pump
-new OEM fan clutch
-Hesco high flow thermostat housing
-Stant Superstat 195*

Then it ran 200-205* consistently even on the hottest days.

 

[SwampSurvivor]

I'm using a koyorad in it now. Up until this year I've never had an issue. I even had it rock crawling year before last in 95* heat with the AC full blast and never went above 210. Then the AC clutch burnt out

I did flush the coolant a few months ago. Well did a drain and fill. The coolant that came out looked pretty good. I'm not losing coolant or oil so I'm hopeful that it's not a cracked head. If it is, I have a line on a 0331TUPY that I can get pretty cheap.

With that said, I am pretty sure this engine has a burnt valve. It's had low compression on one of the cylinders for a few years now. It was doing the stupid vapor lock thing and I was not having it, so I just got on the highway and held my foot to the floor for a few minutes. After that it's had a weak cylinder and you can hear it while cranking. I think doing a leakdown test is going to lead me to that. And it's been pretty down on power for a while now.

The pencil test is sticking the pencil in the fan. If it breaks, good fan clutch. The fins on the radiator are clean. I spray it out from the front quite often and when I changed out the fan clutch last month, I sprayed it from the back pretty good -- but there wasn't anything other than a bunch of coal dust in there.

Tomorrow I'll pull the water pump out. Hoping that's the problem. I can get a new water pump and outlet tube for $50 or so, not too bad. And changing coolant on a completely cast iron engine is ever a bad thing.

Originally Posted by WyrTwister


I too wonder why you have had to replace a radiator hose multiple times ?


With the extreme angles I run this thing, the battery always drips the acid water on the upper radiator hose and eats the rubber. But it always ensures that I have the cooling system burped.

 

[atikovi]

Don't waste your money on a $50 water pump unless you're dumping the truck. You'll be doing the job again in a year or two. I just put in a Mopar water pump and 180 degree thermostat into a Wrangler TJ and it has a new radiator from the previous owner. Needle on the gauge stays 1/8 inch below the 210 mark at all times. Idling or cruising in 95 degree heat. Not sure how sensitive these engines are to trapped air but I used a vacuum filler to be sure.

 

[SwampSurvivor]

With the exception of the closed system on the 87-90s Renix 4.0 Cherokees, 4.0L cooling systems always burp extremely easy. Just bring them up to temperature and let them cool a few times and they'll completely burp

 

[another Todd]

Don't know if this is relevant here, but I have found 1 overheating issue caused by a water pump gasket that was too thick causing the impeller to be too far away from the block to pump efficiently. Removed the thick gasket and used RTV instead and all the heating issues went away immediately. You must put the pump on bare first and spin it by hand to ensure clearance, if it clears it doesn't need a thick gasket. That was on an 82 Celica, don't know if the jeep pump is a fully enclosed unit or if it uses the block as the second half of the pump.

 

[CBR.worm]

If you plan to keep the jeep for a while, an AGM battery might be a good investment to keep the acid on the inside.

 

[SwampSurvivor]

Well, poop. Drained the coolant out and maybe a gallon came out. I put at least 2 in when I changed it last month. It wasn't pretty looking either. Unfortunately the water pump looks brand new with no corrosion. So im going to throw it togethet with a 180F thermostat and run it until the engine is no more. The condition of the Jeep doesn't warrant a new head or engine.

 

[t1snwrbrdr12]

A good cylinder head isn't very expensive is it? The labor is pretty easy as well, nothing you can't DIY at home with basic tools.