90 cherokee overheats

[Sly8795]

1064323

I blew a head gasket in august and ever since then it overheats when the temp is close to 70 degrees out but only when im idling or going slow in traffic when i drive it goes back to normal. Since its been winter no one really knows whats going on but its starting to do it now that its warming up. its been just sitting in front of my house right now till it gets warm. I dont know much about cars but any suggestions. maybe thermostat or busted radiator.
thanks much[addsig]

 

[remember5]

1064339

Since it only gets hot when you are idling, your issue almost has to be fan related. When the work was done in August, was the fan shroud put back on? If there is an electric fan, is it working? If its a serpentine belt, is it run correctly? Does the jeep overheat if you don't have the a/c on?
I don't think the thermostat would cause it to overheat at idle, it would overheat at speed if it was stuck closed. If the radiator was busted, there would be antifreeze leaking somewhere, and you would notice it, plus the level in the reservoir would drop continuously and need refilling.[addsig]

 

[MudderChuck]

1064347

I´ve seen a very slight head gasket leak into the cooling system cause overheating. Check for bubbles or foam in your coolant. Check to see if you have to add coolant, once in a while. When the motor gets up around 220, does the elelctric fan come on? Air bubbles in the coolant system will cause periodic overehating. Park on a steep incline nose high and rev it up a few times. Or crush the top radiator hose, with your hand a few times (often where the air settles).
Like Remember said check the fan clutch in your mechanical. Take a close look at your radiator, is the outside partially clogged with mud or dust. Between the cores, crud sometimes collects, hard to see without a flashlight and a real close look.

edited by: MudderChuck, Apr 17, 2003 - 04:23 AM[addsig]

 

[MudderChuck]

1064350

One thing I forgot you can do, is pull the radiator, flush it backwords bottom to top with a garden hose (at low pressure) and see if your radiator might be plugged with the gasket junk that fell down into yout water jacket when the head gasket was changed. I´ve gotten in the habit of putting the foot part of an old pair of panty hose inside the top radiator hose after an engine rebuild (kind of like a filter) you´d be surprised at how much junk collects in there. I once found most of a handful of sand, left over from the casting of a block and dislodged during the rebuild.[addsig]

 

[dingus]

1064377

the '90 XJ's have mechanical fan clutches... i have had quite a run-in of overheating problems. since august when i bought my XJ, i have replaced the thermostat, radiator, and fan clutch. all 3 install jobs i have writeups on my website in the tech section...

http://dingus.tqhosting.com/

in your case, i would do the cheapest things first. flush your radiator and replace (if not just remove) your thermostat. see what happens from there. when my radiator was replaced, it was NOT leaking, but it was just clogged with CRUD to the point where the coolant could not reach the fins for cooling.

-nate[addsig]

 

[exjay33]

1064383

Sounds like a plugged radiator, gets enough air when you are moving.[addsig]