Help overheating!!!

[1989JeepMatt]

Hello all -

I have a 1989 Jeep 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 Massachusetts.

 

[Hazrider]

did they flush the whole cooling system or just the radiator? You cooling jackets in the engine may be partially cloged.

It makes sense that you would not overheat going 75mph and would overheat in traffic. The air travleing over the enigine and radiator helps to cool the system.

 

[redrooster]

Got mud in the radiator veins?
Have you tried an aftermarket temp gauge to see if your factory one is correct?
Did you check the fan clutch (if it has one)?
Did you buy any of the above stated parts from Autozone?

 

[LBR]

Did you replace the lower radiator hose? LBR

 

[guysmiley]

From the sound of it, you replaced everything. Are the parts OE or cheap aftermarket stuff? Like one said, make sure their not autozone parts. Especially the cheap thermostats. If you still have the fan clutch, check when engine is cold, should spin with little resistance. When the engine reaches higher temps, the clutch should have quite a bit of resistance to it. While driving, the air will help cool off the radiator, so that would explain the normal temps at higher speeds. A proper operating fan clutch should be fairly loud when warm, and engine at higher rpms. If you have a/c, make sure the fins are clear of debris. Go to a station with the quarter air machines, and blow out the a/c condenser with pressurized air. You will be suprised what comes out. Do you have a wiring diagram? You possibly have a bad gauge, ground, temp sensor. Let me know if you don't, I could email you a complete diagram. To see if the thermostat is the problem, when the engine starts to overheat, shut it down, feel the lower radiator hose. It should be warm and able to be compressed. If the upper hose is bulging/ hard, and very hot and the lower hose is very cold, you possibly have a stuck thermostat. Did the mechanics chemical test the cooling system to see if exhaust fumes are in the cooling system? Thats an indication of head gasket/ warpage. An engine will overheat also if it is running very lean. Lean mixtures raise the cylinder temps. Before I forget, if you have electric fans, and someone took them out to access another component, make sure they are spinning in the proper direction. They might have been rewired wrong. Hold a piece of paper 1" from the front of the radiator. If the fans are working properly, it should pull the paper to the radiator with little effort. That could also be used to check the condition of the fan clutch. I have replaced a good number of rebuilt water pumps. Sometimes the rebuilt pump will have a slipping vane. The pulley and belt spins fine, but the vane in the block will not spin fast enough to circulate the water properly. Good Luck
Guysmiley