1988 jeep cherokee overheating

Cindi

New member
I am new to this forum & new to jeeps. Husband bought this jeep for me, I love it! Today it overheated, can't figure out why. 3.8 liter, the resoviour keeps bubbling over, new thermostat too. can't figure out why. help!
 

Various reasons for the six cylinder (I'm guessing. 3.8 liter in an 88 doesn't ring a bell). Most common is because of a partial air blockage inside the motor. This can happen for various reasons, a recent radiator service, the reservoir ran low (I keep mine half full cold) or a very small leak.
If you have the original radiaotr in an 88 it's likely partially plugged with deposits. There are other common problems, but first things first, exactly what motor do you have? Four cylinder gas, diesel, or in line six cylinder gas?
 
Sorry, guess all that info would help. straight 6. Took to guy who works on cars, said either the head gasket or water pump was bad, either way, $100 to find out, too much $ to fix head gasket. Thought maybe it just had to many air bubbles in it, ran it without cap on resiv, didn't work out that way.
 
Could be other causes as simple as an overflow tank that won't hold pressure. I would park the jeep facing nose-down and remove the temp sender from near the back of the head. Fill with coolant until no more bubbles.

Water pumps cost less than $100 and are easy to replace if you want to rule that out.
 

Sorry, guess all that info would help. straight 6. Took to guy who works on cars, said either the head gasket or water pump was bad, either way, $100 to find out, too much $ to fix head gasket. Thought maybe it just had to many air bubbles in it, ran it without cap on resiv, didn't work out that way.
Common problem for the Early (87-90) in line sixes to have an air blockage in the motor. Bounties method is th best, though I've had reasonable results crushing the top radiator hose and releasing a dozen times, with the motor hot enough to have the thermostat open.
Air (bubble) blockage in the motor, partially plugged radiator, small leak either in the reservoir or someplace else in the system, pressure cap for the reservoir or bad thermostat are the usual problems.
With a poorly functioning mechanical fan clutch, usually causing high temps at idle and a non functioning auxiliary electric fan as alternate possibilities. Did your auxiliary fan come on when it overheated? Does your auxiliary fan ever come on? Does in come on when you use the air conditioning?
Head gasket and water pump are pretty far down the list of causes in my experience. The water pump usually fails by leaking and a head gasket problem often causes bubbles and foaming in the reservoir. A leaky head gasket can also push some coolant out the exhaust, an easy test is to use a white paper towel and blot a little fluid from around the exhaust end right after start up, coolant is colored (green, red, yellow whatever) and the condensation can show some color on a white paper towel. Head gaskets also often cause serious missfires at idle, what I call a hard miss. Head gasket failures on the inline six are not unkown, but rare. When the head gasket fails it usually leaks oil outside the motor, not coolant into the cylinders, though it's been known to happen on occasion.
 
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