1991 Jeep Cherokee 4.0L 4WD Thermostat problem?!?

[spookykl]

Ok, today, I drove the jeep to work and it was parked under the sun from 8:45am - 4:45pm. Today was the hottest day also! We recorded a temperature high of 32degrees Celsius. So, driving back home, after 30min...this light flicked on (the symbol that looked like a thermometer)...so, i quickly turned on the vent to High and to hot air..and kept it blowing until the light shut off. After that, i turned it off..and that light came back out again! So, i decide to keep the vent on.

After i got back home, i parked and opened the front hood...and boy, it was HOT inside (I didn't see steam though). I've checked my engine coolant..and i'm 1/4 way down only. Checked the engine oil..and i'm slightly in the "add" zone. I've touched the radiator hose and it was quite hot. I'm wondering, what's my problem? Do i need to install a new thermostat? Flush the engine coolant? or is there something else wrong with my jeep cherokee?

Thanks!

[RebuildinXJs]

Hello, I just sold my 91 cherokee last week , it was my 3rd one, but it ran hot all the time. I did alot of looking on the web and found that xjs have cooling problems. I was running about 230 on the freeway, or when using acc. The best and cheapest way to troubleshoot or remedy this in my oppinion is to flush the raditor and whole system and add the correct amount of antifreeze and coolant. I would also run a 165 degree thermostat. Check if the electric fan is working. My xj would only run hot at freeway speeds or when using the A/C. The radiators are undersized in my opinion, and having the A/C condensor in front of it doesnt help the air flow. Prob nothing you havent heard , but maybe somewhere to start.

[BCBlues]

This will cure your problems.

http://www.automotiveforums.com/vbul...tor+conversion

[capt. apathy]

flush it, replace the thermostat, and do your best to get as much air out of the system as you can.

the upper radiator hose is a huge air-trap, when you are filling the system a lot of air will be trapped in the top of the radiator, the upper hose and even some in the head. it's not easily removed since there there are no vents in that part of the system.

the best way I've found to get the air out is to park the jeep facing down a steep hill (or you could use ramps. whatever, just get the rear end as high as possible), squeeze as much air as you can out of the upper hose and back into the head, then pull the sensor for the temp gauge (drivers side rear, in the head), air can then escape out that hole, when you see coolant replace the sensor, top off the coolant, and repeat the whole thing until you don't find any air.

I've also found that drilling a small hole (<1/8") in a new thermostat will help avoid a lot of trapped air.

good luck, a large share of the posts you read will be about this problem. just about everyone has or had the problem. the cooling system is just very poorly designed and (as the post above mine says), if you can afford to replace it with an open system, do it.

[spookykl]

how do you flush the radiator system?

drain the antifreeze, add water, start car for 1-2min...shut off car, drain water, repeat water step..and then add antifreeze back?

also, where is the drain located on the jeep? i have a hard time looking for it...

[capt. apathy]

the drain is on the passenger side of the radiator, a real pain to drain, it goes everywhere.

I flushed mine almost daily for about a week or so before it started running clean, ( I was big on time and low on cash at the time). I pulled the thermostat and ran it with clean water in it (so I wouldn't have to worry about containing the spills).

then I'd take off the top hose at the radiator and run water into the hose, until the water coming out was clean.
eventually debris stopped coming out.

it would be much less hassle to just go have it flushed at a shop (but wasn't in my budget at the time), and they'd probably be much more thorough.

[gtmud]

Over heating?! I have a 00" XJ at 21,000 developed an over-heating problem. Turns out that the ENTIRE system was clogged! Yes, I tried flushing, it looked good (fluid) only after cutting one of the heater hoses in half did I find a rust like deposit coating the entire tube, you might want to get you radiator checked, then your heater core. Good luck. Since the entire system was replaced (warrenty!!) At 84,000 miles, no problems.