1988 cherokee overheating

[irishsetter48]

I have a 1988 cherokee limited. It overheated today and blew antifreeze all over the parking area. I added some 50/50 after it had cooled down. I started it and as the temp gage creeped toward the red zone and I watched the overflow tank drain and then start to refill with a slooshing vengence until it blew past the cap. A mechanic replaced the thermostat a few months ago. Anybody have suggestions on where to look first? Thanks for your help.

 

[Bounty__Hunter]

My quest for rubicon begins

Does it overheat if it just sits in park and idles? That would rule out the auto transmission not locking up the torque converter and overheating the transmission fluid. The '88 AW4 has it's own computer and all signals have to be correct or it'll cause all kinds of problems. Any shifting problems?

If you decide on a new radiator, check out www.radiatorbarn.com for inexpensive replacements with warranty and quick shipping.

 

[irishsetter48]

In fact, I was able to drive it home last night (under cover of darkness and cool). The gage stayed near 200, unless I was idling at a stop light, and then it started creeping. I had the heat on full and the fan on full to take heat away from the engine.
The overheating happened the first time when I was driving (hot day in maryland with AC on). After waiting 30 minutes for cool down, I added 50/50 and started it up. Within 3 minutes the coolant had filled the over flow tank and blew past the cap.

 

[MudderChuck]

Could/probably have more than one thing going on with your cooling system. If it´s the original radiator, the chances of the bottom 1/4 of the radiator being full of dirt rust and stuff is pretty high. After servicing the system, you have to be sure and get the air out. Air bubbles mess with the flow. Various methods, one when filling, remove the temp. sender from the drivers side rear of the block (motor off), lets the air out, until you get close to full. Another is to park, nose up hill, at operating temp. and reving it up some.
If you have any kind of leak in the system and/or the surge tank gets below half, it will suck air, when the motor goes into cool down (stopped).
When thermostats get overheated, they sometimes act up.
Fan clutch gets old, usually acts up at idle.
The cap on the surge tank gets plugged with, calcium, doesn´t vent right and/or the surge tank seeps, at a crack and/or the cap seal.
Don´t use a universal, themrostat gasket, unless you cut it the same as the OEM, gasket (special cutout for the surge tank/heater/bypass circulation system). Newer thermostates have a bleeder hole at the top of the thermostat, to help with moving the air through the system.

 

[irishsetter48]

MudderChuck,
Thanks for your suggestions. I read several of the "overheating" topics in this forum, and I followed their advice and checked my fan clutch. The fan moved freely when the engine was cold and the fan moved freely when the engine was at operating temperature. So I will be putting a new fan clutch in this weekend. Then...I will work on getting the air out of the system. Thanks for your "tricks of the trade"...they're not mentioned in the manual.

 

[MudderChuck]

Most of the helpful hints, I picked up, while trying to get my 88 XJ, closed system to work properly. Eagle at www.naxja.org really know´s his cooling systems. His no chit assesment and recommendations squared me away. New radiator, new surge tank (and cap), use of calcium free water (rain water or distilled), new thermostat (with bleed hole/dealer) and a fan clutch cured my problems. I tried the cheap/easy fixes, that were msotly a waste of time, and finally, listened to Eagles recommendations, which cured the problems.
There are some air traps in the XJ closed system, that cause problems, after a cooling system service. One is at the back of the head, another seems to be at or near the themrostat, still another on the large tube to the top of the radiator. Filling the system, with the temp. sender removed will get you air free to the temp sender outlet, the newer thermostat with the bleeder hole, will get you air free to to and/or past the thermo. And crushing the top radiator hose, with both hands, with the motor at operating temp also helps move air out of that region, into the surge tank.
Could be other issues with your cooling system, but with trapped air in there, it is hard to troubleshoot the other problems.

 

[irishsetter48]

Dang! I purchased a new fan clutch and put it on. The jeep didn't overheat, but it sure didn't stay real cool either...rolled past 210, but not all the way to the red zone. I thought the fan clutch was supposed to be nearly immoveable when the engine was hot. My new one spins freely with the engine almost too hot to touch. Did I mis-read some of the threads in this forum? The reason I replaced my original is because it moved freely when the engine was hot. Your opinions are appreciated...thanks.

 

[MudderChuck]

Sagging cj

fan clutch usually makes it overheat at idle. Fan clutches come in left and rights. Way to check it is to shut the hot motor down and then run to the front and try and spin it, should feel some resistance. Clutch is full of silicon and the round and round slings the silicon to the outside increasing the resitance, if you let it sit for a few minutes it will sometimes, loose some of the resistance.
Think much of your problem is a partially stopped up radiator and/or air trapped int he system, clutch probably also played a part in the trouble. Many times it isn´t just one thing.

 

[irishsetter48]

Mudderchuck,
So I'm thrilled that the car runs real cool and everything seems to be great...until I run through the emissions testing today and the test guy says "ya got a little coolant leak". So I'm thinking "there goes the water pump"...but the coolant is leaking from the right side of the block. What the heck is on the right side of the block that could leak coolant? I have 190,000 miles on the jeep...is it time for a head gasket? Thanks for your help.

 

[irishsetter48]

2" BB .... CHECK!

ok, ok, ok...so I didn't see the big lower radiator hose that was leaking near the top hose clamp. I did when I got my halogen light under there...and the new hose clamp has returned my cherokee to cool (literally). Mudderchuck, thanks for your help.

 

[mud4feet]

ok, ok, ok...so I didn't see the big lower radiator hose that was leaking near the top hose clamp.

Congratulations!! Another member of the idiot club!!! Welcome aboard - we are a proud bunch!!! :lol:

 

[jeepmaster]

i think that just leaves air in the system as your only other option?