1989 Jeep Cherokee overheating problem

[Isaacm1986]

So i know there are a TON of jeep forums out there, but I wanted to post my question here for my fellow Iboat peeps!

I have a 1989 Jeep Cherokee, it is my tow vehicle and it is a bad time for it to be down. It has the 4.0 Liter motor with 245k on it. Today it started overheating on me. I changed out the upper radiator hose (which was going bad) and flushed the whole cooling system but it is still over heating. The fans are working. I have heard that these old jeep cooling systems can be picky, just wondering if anyone has any experience with these old closed radiator systems.

thanks.

 

[bruceb58]

Re: 1989 Jeep Cherokee overheating problem

How bad did it overheat? What are the symptoms now? Is it just getting hot or is it blowing all the coolant out. If the latter, you may have overheated bad enough that you warped your head and blew out your head gasket.

Assuming it isn't a head gasket, does it overheat while you are driving normally or when you are idling? Very possible the radiator is clogged up.

 

[ezbtr]

Re: 1989 Jeep Cherokee overheating problem

thermostat?

 

[dockwrecker]

Re: 1989 Jeep Cherokee overheating problem

I've got one also. They run pretty warm normally (about 210) so any little thing that's out of whack will send them over the edge.
Easy stuff first.
Replace the thermostat, check thouroughly for leaks everywhere-radiator, water pump, hoses, heater core etc.- any leak will cause it to boil.
Replace the radiator cap.
Check your oil for signs of water ie chocolate milk appearance. (this one's bad if it's there) 4.0 engines aren't fragile and they rarely blow head gaskets, but have a look.
If all is well so far and it still overheats theres a problem with the radiator. They don't hold up well but if you've got 245k out of yours it owes you nothing!
The one fragile part of a Jeep cooling system is the radiator. Fortunately you can buy a new one with a lifetime warranty for 66 bucks on Ebay. I just had to do mine a couple of months ago. Sort of a pain to change, Jeep pretty much starts building a Cherokee by putting the radiator on a stand and attaching the rest of the truck to it. But it fit perfectly and was of very good quality and no more leaks. Hope this helps.
Good luck!

 

[kend301]

Re: 1989 Jeep Cherokee overheating problem

I have worked for chrysler / dodge / jeep for 9 years , Check the waterpump , they are notorious for a slow leak out of the weep hole that will run down the lower radiator hose and, Call your local dealer and have them check for a cooling fan recall , Not sure what years are envolved but I think it is recall F25

 

[Isaacm1986]

Re: 1989 Jeep Cherokee overheating problem

Thanks guys,

I am going to the auto part store to get some stuff. I am going to replace the thermostat, radiator cap, and do a check for leaks.

I am begining to think that it is the cap, with the cap on I can blow in a hose and it will just let air out. It does not seem to be holding pressure to me.

If those do not work, I will go for the water pump and new radiator.

I will let you all know what happens.

 

[rbh]

Re: 1989 Jeep Cherokee overheating problem

I hate plugged rads, Only use glycol and "demineralized water" , learned that leason the hard way.

 

[Isaacm1986]

Re: 1989 Jeep Cherokee overheating problem

well i put a new thermostat in and it definitely has helped the issue but not cured it. It does not over heat near as fast as it was. the new pressure cap comes in around 1pm at the auto part store, so I will put that on and see what it does.

If that does not solve it, I will start tearing into the heater core and radiator replacement. I am tempted just to replace everything in the cooling system so i don't have to worry about it anymore.

Has anyone ever converted these old closed systems to a open system? I know jeep did the conversion in 92, but mine being a 89 I am still using the old system.

thanks for the help.

 

[642mx]

Re: 1989 Jeep Cherokee overheating problem

Check the impeller on the pump. I've seen a bunch of high mileage waterpumps (mostly GM's but some Chryslers too) where the impeller has rotted away. The blades are still there, but they are so deteriorated that they don't push the coolant properly causing the system to over-heat.

A cap is a good idea... but even if a 15 psi cap only held 8 psi of pressure the vehicle would still be reluctant to over-heat. Pressurizing coolant raises the boiling point, but it also makes the fluid heat up quicker.

 

[puddle jumper]

Re: 1989 Jeep Cherokee overheating problem

A word of advice that happened to me when I changed a water pump on a customer's jeep. Make sure that the impeller pumps in the same direction as the one you took off. Apparently the manufactures make two water pumps that look identical but are made to rotate and pump when turned in opposite direction's.
The jeep would only over heat on a long hill but not around town.