Hi, I recently bought a 1991 XJ Laredo that had been sitting for a year and after I got it running it would overheat after idling for a while. Normally it was not for about 20 minutes after it had reached normal temp that it would start to hit the white line. I know that there is a small hole in the overflow line that was patched with tape. Today I after it had been idling for about 15 minutes I looked at the temp and it was all the way red and steam was coming from the engine. I immediately shut the jeep off and opened the hood. The radiator cap spewed some antifreeze and the overflow hose was leaking some. I know that the electric fan is not working and I plan to hot wire it to a switch. After the engine cooled down I opened the radiator cap and the fluid appears normal. The overflow bottle is empty now and there appears to be some sediment in the bottom. If I squeeze the upper radiator hose with the cap on a little fluid goes into the overflow bottle and with the cap off the level rises where the cap is. The oil also looks the same as it did before the overheat as far as I can tell. Does anyone know what would cause this and what problems could come from it overheating like this once? I'm hoping I dont have a blown head gasket and am not sure how to test for it other than milky tan oil. I was also thinking of replacing the radiator and the thermostat had already been replaced. Thanks for any help!

 

i bought a 92 laredo couple weeks ago and i too some what have similar problem like yours. the jeep was sat for 10 months when i bought it. on mine after driving for 10-15 minuts the water temp would hit past 210* and if it's a slow moving traffic and the temp needle would be on the last white mark before the red mark. i just replace the thermostat yesterday and was driving around and the temp guage seem to be on the 210 mark or below if traffic is moving along. i looked at the previous owner receipt and looks like the radiator was replace in 2004. think im going to take to shop and have radiator flush and see if that solve the problem.

 

Fill the system and pressure test it and the cap. If both are good could be trapped air in the block. Flushing is a good start, and easy todo at home in the driveway.

 

if the electrical fan isn't worKing that's your first priority. secondly take some compressed air and blow out the radiator (from engine out to the front). double recommendation on flushing.... and a 9yr old radiator is an old radiator.... I would replace the thermo again especially if it has been sitting and use the orifice as a flushing point. flush the radiator flush the block and flush the heater core.
let us no how it goes.

 

Not really, the electric fan is a back up for extreme heat and the ac condenser. When at rest you should not need the electric fan.

 

I don't think so! If I don't run my ac my fan doesn't come on at all unless the weather start to get hot.
I would never recommend this to anyone unless you are ready to buy them a new one. Even if the radiator is brand ne and you put to much pressure with a compressor you have a good chance of rupturing it.
To the OP do yourself a big favor give the entire cooling system a good once over. Replace the T-stat it calls for a 195deg. flush the entire system. Check out the water pump. And replace the coolant with a 50/50 water antifreeze mix. Then worry about putting in your switch for the elect fan.

 

Flush system several times fully then drain everything. Remove thermostat and run water into engine till clean water comes our below. Then go to a parts house and buy a new thermostat and radiator to go with it. We just finished doing this to my sons 98 XJ "AFTER" a thermostat, water pump, fan higher CFM, radiator cap all no help..... then the new radiator Wa Lah fixed it. This should have been done first these radiators are old enough and it seems most are neglected badly its just a good idea to replace them to do what we ask of them.

 

How would I go about pressure testing the system? And are there any specific detailed writeups on how to flush the system? I only have access to a garden hose and pressure washer and I'm not sure what to do. Please excuse my noobishness lol

 

Pull the thermostat housing off (on top of motor above h2o pump) pull both heater hoses off. And pull the lower rad hose. Flush each section individually. Engine block through the thermo. The radiator through the upper hose and the heater core (make sure heater valve is open if u have one) flush until clean water is flowing.

 

I removed the thermo today which looked fine an was astonished by how much gunk was in the engine. Is this something that should be chemically cleaned or will water from a hose be fine? Also will a pressure washer work? And the previous owner I believe installed one of the back flush t-valves on the lower heater hose.

 

Way too much RTV was used on the t-stat housing, it's actually blocking a portion of the opening.

 

I agree. There is way to much RTV. Some people think the more the better. But for things like the t-stat that is way to much and can cause more problems. To OP, You can try some cooling system flush and let it circulate through the system but you may have to do it several times to clear it up some. It looks like the original owner ran it with to much water and not enough coolant. Once you get it cleared out as best as you can make sure that you refill it with 50% water and 50% coolant. How bad does the radiator look. If it looks as bad as I think it does you would probably be btter of changing the radiator.

 

If those chunks get into the radiator tank its done for anyway ....Agree on extensive flushing and new radiator also throw a new thermo housing on there if it looks like the block. Alaso check clutch fan opration when at operating temp.

 

How bout flushing with a weak mixture of muriatic acid?

I've been contemplating it.

 

Not sure on that maybe some else has something better than off the shelf flush....Ive searched cant find nuttin searching my self .