HELP: Jeep Overheating & @ wits end

[1989JeepMatt]

Hello all -

I have a 1989 Jeep Cherokee in-line6 4.0.

It has been overheating very erraticly and I have had the following repairs done to it.

New: Water pump. I have had the radiator flushed and pressure checked. It has been totally tuned up oil, plugs etc - the thermostat has also been changed. The fans are both working properly and the radiator though it came with the Jeep seems fine. I have has 3 mechanics also say that my head gasket is fine as is the overall health of the engine.

The vehicle: It has 182,000 miles but the engine is strong. The problem besides the overheating is it has many electrical problems. The most prominent problem is when I start it, it occassionally idles very very high and will not come down unless I shut it off and pop the hood, then wiggle the fuel injector bar wires on cylinder 5 and 6, the restart it. My rear defrost also will not shut off and I hear a clicking capacitor every few weeks under the dash which is weird - other electrical problems which I have are minor - flood lights no work etc.

A recent example of erratic overheating is this: I drove 100 miles non stop at 75+mph and the temp was a perfect 12:00 o'clock normal - hours later I overheated in traffic and also was unable to travel at 55mph without running a very high temp - starting off with a rested cool engine.

I have spent more than I can afford now and am reaching out to you all.

Thank you,

Matt in Mass.

 

[90Xjay]

Matt,
Welcome to Jeepz. Glad your here.

First, what is overheating? An XJ with a 4.0 will run up to 210 F normally, although some will run just under 200.
It is a hot running engine and 210-212 is not overheating. If by overheating you mean water spewing out from under the cap, yeah then we have an issue. If you have the closed radiator system, the coolant reserve tank on your jeep is plastic and so is the screw on cap. If the threads on the cap or tank are worn it will let pressure seep out and will make your jeep run and act hot. The only way to fix that is a new tank which comes with a cap for about $35 dealer or less on ebay.

I'll be it is nothing big. Another important thing to think about is that if you are having electric problems, keep in mind that the guages are ran off of electric current and it is possible that all or one of them could be giving a false reading. If you have access to one of those temp guns where you point it at something and pull the trigger it would be nice to know your guage us accurate.

keep us posted.

90

 

[dingus]

If you have the closed radiator system, the coolant reserve tank on your jeep is plastic and so is the screw on cap. If the threads on the cap or tank are worn it will let pressure seep out and will make your jeep run and act hot. The only way to fix that is a new tank which comes with a cap for about $35 dealer or less on ebay.

i concur - that would be my guess. You should have this "closed system" unless someone upgraded it...

 

[1989JeepMatt]

Thank you for replying guys: It is overheating and runnning about 230, and just under the red line at times - the Jeep is a Cherokee 4.0. I have a closed coolant system and the threads on the cap seem ok -do you reccommend a higher grade radiator? Something very heavy duty - could my radiator not be flowing well? or what I wonder the most about: could this be an electrical problem.

Look forward to your reply,
Matt

 

[Bounty__Hunter]

Can you hear a pressure release when removing the cap to the overflow bottle?

I recommend a new radiator.

 

[90Xjay]

I know you had the radiator flushed, but that really does not do much except change out the coolant. Any real problems like partially blocked cooling tubes have to be cleaned out with a rod with the tanks off.

If it has never had that done, it could be plugged up inside. If you are going to go to the trouble, you might check prices for a new one instead. you can get a good price for your old core.

I still think the pressure bottle and cap are suspect. The threads look fine but still allow pressure to bypass. A system without pressure will overheat.

 

[GaryMB]

Does it overheat consistently, or is it unpredictable weather it will overheat under the same conditions? If it regularly overheats under harsh conditions, I would bet there is a mechanical problem like the system loosing pressure or a clog in the radiator, but if it is erratic, then it would not be improbable that the problem is electric, such as fan thermostat, relay, ground, etc.

 

[1989JeepMatt]

The overheating is consistant at times, but having recently driven from Burlington Vt to Concord NH at 75 to 80mph (which is alot for my Jeep) with out issues at all then boom it shot up later in the day back in boston makes me wonder about electrical issues. But in the mean time maybe it finally pressurize from VT to NH and things were flowing as they should have been. I also think that a heavy duty radiator may help. I plan to replace the over flow and the radiator - but is there any thing in the arena of electric issues that could be causing this? As it is I have a bunch of electrical issues and I dont even know where to start regarding gettiing that addressed. I might as well get everything right since I am driving with 2 kids and the last thing I need is a night time overheating on Rt. 93 with a blown hose or radiator.

I am very grateful for your help guys,
best wishes.

do you all have any thoughts?

 

[rivired67]

My Friends 89 with the closed system overheated just like ur situation..he put a new radiator in it and it fixed everything.even tho his SEEMD to be fine..upgrade to a tripple core while ur at it..available at most auto parts stores..also make sure to get ALL the air out of the system..its a major pain int eh ass but will cuase probs if left.