Another Overheating Thread

[CrazyCory]

Hello, Ok so i will be going down the road at about 65 for 15-20 minutes and my XJ starts to overheat. After about 25 minutes of driving my XJ is about to 260*. I have changed the thermostat and did a cooling system flush. The head gasket was changed about 2 1/2 years ago. Not sure really how long they last. I just know thats when it was changed cause I have the records from the previous owner. My fans are working fine. Please help me out. Just some info. I have a 1992 XJ Limited. 4.0, AW4, NP242, Dana 35 (R), Dana 30 (F), :confused:

[XJ Wheeler]

First off, i would NEVER let it get up to 260°. That alone can crack a head, or worse.

If you have a way, do a compression test. Just wanna check on that head and gasket.

Overheating at speed only generally means its a coolant flow problem, not air flow. 65 mph kinda takes that whole fan setup out of the equation. So, i would use an infrared thermometer to check for hot spots in the radiator/hoses/etc and you might as well confirm the temp gauge is correct while you're using it.

Hope this helps, overheating sucks.

[Cheromaniac]

Overheating at speed only generally means its a coolant flow problem, not air flow.

Exactly, and unless you have something obstructing airflow through the radiator (winch, AC condenser caked in mud), the chances are that the radiator itself is clogged up with 21 years' worth of rust and limescale deposits that even a flush cannot remove. Time to invest in a new 2-core radiator.

[bulrid8]

Yep, overheat at speed useally means either clogged radiator or bad pump. That would be first things I would check.

Sent from my ADR6400L using Tapatalk 2

[4.3LXJ]

Got shrouds on the fans? Winch or driving lights in the way?

[prcjeep]

Are you losing ANY coolant fluid? The connections on the radiators between the aluminum and plastic tank on the side will swell over time and begin to seep and usually goes unnoticed because it evaporates.

Im also going to say radiator.... $115ish from auto parts stores with lifetime warrantee.

I cant remember if the 92 has the open or closed system(someone chime in) but I believe it is fairly simple to swap it to open at the same time as replacing the radiator.

As for a pressure test on the coolant system, autoparts stores rent radiator cap testing kits. Instead of testing the cap you can put it where the cap goes and pump it up to see if it holds pressure. This may not work on a closed cooling system.

[Mudderoy]

Yep replace the radiator. I think the XJ radiators need to be changed every couple of years if you really got down to brass tacks. A couple of us have had good luck with a single row large diameter tube aluminum/plastic radiator from Amazon. $140 I believe. Now recently I bought a 2 row all aluminum Champion (I believe) from ebay that was about $210 after shipping. I haven't seen a difference between it and the single core I mentioned first.

[XJ Wheeler]

'92 is open cooling system. ;)

[nateyz2000]

Mine runs at 170 at highway speeds.... It's the slow stuff and trails that brings it up to 220.... Which is too high for me... Then my 2 row champion radiator, aux fan adjustable thermostat, and a super cooler tranny cooler... Seems all well ... We will see how she does on the trail!

[Brasscatz]

Mine runs at 170 at highway speeds.... It's the slow stuff and trails that brings it up to 220.... Which is too high for me... Then my 2 row champion radiator, aux fan adjustable thermostat, and a super cooler tranny cooler... Seems all well ... We will see how she does on the trail!

running hot at slow speeds could indicate your fan clutch isn't 100% too.