I've had my 89 Laredo for about a month now and its been overheating non stop since then. Initially it was overheating within 5 minutes of driving it so I replaced the Thermostat, followed by the radiator(I upgraded to the open cooling system at that time).

When that failed to improve anything I changed the water pump and all the radiator hoses all to no avail. I had a professional test for a head gasket leak that resulted in a negative.

Finally I heard that i could have an air bubble that was trapped in front of my thermostat because it did not have a weep hole. So 3 days ago I took it out to try and rule it out as the problem. It worked!... until today. I was in stop and go traffic on my way home from work today and it overheated again!

Additional Info:
The oil pressure is between zero and a quarter of the way up the gage the whole time.

The whole Jeep shakes violently if when I hit small bumps in the road going anywhere form 35 to 65 mph. It only shakes when its overheating

I lose my blinker when it overheats

I am completely out of ideas so anything you guys can think of can help and will be greatly appreciated. Thanks!

 

Have u replaced the fan clutch?

 

this is the most over looked part of the cherokees cooling system. I'd start there.

 

Also, just have to ask, is it boiling or just hot on the gauge? I wouldn't ask, but 5 minutes is pretty quick, and the blinker thing and the oil gauge. Zero is a little on the low side!

 

i had to replace mine once for a similar overheating problem

 

check your oil level. low oil is the quickest way to overheat a motor. i would probably just go ahead and just change the oil right away too. also keep a close eye on the antifree level until u get it to stop over heating

 

and also if you havent already, go back to a stock pressure cap, zero pressure is to slow a leak down at the radiator for people too cheap to get it fixed lol.

 

Have you replaced the radiator and flushed the system. I recommend a CSF 3 row.

 

if u still hav the plastic tank thats ur issue go to macsradiator.com and get a surge tanks it solved my issue

 

how about the temp sensor, not super familiar with that year, but a crusty sending unit could cause issues

 

when its overheating ,are you going by the gauge or is it boiling over as in coolant all over the ground???????

 

Overheating won't affect the blinkers.
You have an electrical problem - the gauge is fooling you.

 

X2 on gauge

 

Probably not the gauge itself. The power to the dash and the entire electrical system is fluctuating - even makes it run rough at times.
Check battery connections, check grounds, check fuse block backside for corrosion.

Unplug alternator - see if it stabilizes.

System voltage is fluctuating - use a separate voltmeter to track it down.

 

Thanks for all replies! Ill Try to answer all the questions. I googled how to test a bad fan clutch and mine is bad so I will be replacing that this weekend. Ill let you know how it goes!

No it is not boiling over the gauge makes me worry to much so I try to cool it down as soon as I notice it shoot up.

As far as the electrical problem goes, does anyone know of a thread that has a detailed diagram or of the whole thing? Or how exactly to track down the fluctuating voltage?

Thanks Again!