So my question starts here...

I have had this 88 XJ for a long time...10ish years, and she has many many miles. Odo says 388k tire math gives me roughly 500k.
But back on topic. She doesn't over heat when i climb hills at say 45mph+ steep or not. If i can keep the speed up it is fine enough to climb any hills until the cows come home.

However if I climb hills at say 35 or lower I won't make it more than 5 minutes before I have to stop. If i can get the speed from there up to 45 or higher it's fine and will cool back down.

It has been doing this for years, and I figured just cause the extra airflow over the engine is keeping it cooler. Idling it's fine, just on hot days I have to run the electric fan. I have just been ignoring it cause most cases I could avoid it.

Wheeling and having fun have had to leave the equation cause it just can't do slow speeds at any amount of work. Even last winter when i was climbing a pass at 25 during a blizzard. It overheated while i was running my aux fan, and heater.

Newish radiator, new condenser so no airflow problems. I can turn on my electric fan by switch, and run the heater as necessary to help alleviate the problem...

Hoping to bounce the problem off other people's heads. I just am stumped...
Thanks for reading!

 

Have you ever changed out you fan clutch? If not I would look into starting there.

 

That age and those miles it may be time for some cooling system TLC, ya think? Wonder if the water pump could look like this? Is a newish rad the same as a JY rad?

 

Honestly I am just thinking it has something to do with the engine timing. I am just stumped from trying everything else. It started right after changing the CPS.

Yesterday I was climbing a steep grade at 20 not working it hard. But it went from the happy 210 to red temp inside 3 minutes. Earlier before the grade i was cruising the interstate at 70 climbing hills and doing okay.

I really hope my water pump doesn't look like that it was new a couple years ago...Sad if it went that quickly...
Though I did just again seal up all the leaks in the hoses so the cooling system stays pressurized, didn't do a darn thing to fix it.

Fan clutch still works well enough i am sure, it behaves as it should.

Thanks guys. I personally find it helpful sometimes to get others opinions at times. I have figured out many things just talking with other people about it...getting me to look at the problem the way they are.

 

It ain't timing....

How did you TEST your fan clutch? I've not found a reliable test in 27 years of being around these Jeeps. You have all the classic symptoms of a bad fan clutch.

Also, put a Napa 703-1396 cap on the coolant bottle.

 

I'm stumped at what "trying everything else" means. All I've seen is "newish" radiator.......what does that mean?

 

Yep.

If the fan clutch is bad, that would explain the low speed heating.

And, lack of pressure on the system due to the crappy original cap would only make it get hot faster......

 

Wonder how u seal up leaks in hoses?

 

Fan clutches are difficult to fully test. There's the freewheel on hot shutoff, newspaper while hot spinning test, the locked up constantly test, etc... but they can and do lose their effectiveness over time. I just changed my a few weeks ago because of A/C performance issues. The original fan clutch passed every test I had ever read but simply wasn't moving enough air. $35 at NAPA or about $100 at the dealer. Hoses tend to disintegrate from the inside out and should be done about every 10 years if not sooner.

 

Thanks for your help, sorry about the details I just don't know exactly the details that would help so i try to summarize.
I will look more into the fan clutch, it has just been something i haven't looked into terribly hard into. Worst case mine doesn't disengage and stay's locked in. But like both of you said I really don't know the complete status of it.

All new radiator hoses was how I fixed the leaks. And I see in the plastic over-spill bottle that fluid is moving nicely. So I could safely say that the water pump is working. On a cold start, last time after changing the hoses I saw the thermostat working properly.

And yeah stock plastic over-spill bottle for the coolant. The bottle itself is only a year old so maybe another 2 years tops out of that bottle. Will look into the bottle cap but I am pretty sure I got the equivalent from CRAP auto with the last bottle. But will still look into it. They had mentioned that all the newer bottles had been changed over to a new thread to keep the old caps from threading on.

But here is a list of things i have tried to fix the problem during the time span it has been giving me problems:
New condenser
New Radiator (Was the first thing I changed when I noticed it wasn't staying cool 3-4 years ago, it helped slow it down, but didn't stop it from overheating)
Re-wired the aux electric fan to work when i tell it to "Pretty much use most of the time"
New hoses
Flushed the block
Additive to the oil
Octane Booster (On a side note i have alway's used medium to high grade gas from either a shell, texaco, or exxon stations)

Again thanks for your time.

 

Have you ever changed out the fan clutch in the 10 years you owned it? If not I still say that is more then likely your problem. They don't last forever and once they start to get old you start heating up.

 

Some things to do...wire the electric fan back the way it suppose to work, on it's own.
I posted a over heating problem and after cleaning the connections for the electric fan it started working on its own again.
One guy told me to check my thermostat and if it doesn't have a hole in it...drill one 1/16 of an inch in it. I drilled mine 1/8 of an inch a long the outside edge of a brand new thermostat.
Mine is a 89 4.0 L and that was the last time I had to deal with over heating.
Let us know if this works for you?

 

Dan, you will never get a new bottle with the cap we're recommending, only the same chinese crappo ones that always come with them.

If it were me, I'd get the cap and fan clutch and see what happens from there. Neither of them is a waste of time or money to do.......

 

A hole drilled in the stat will prevent overheating????? Really???? Please explain how. Thanks.

 

My guess it allows fluid to circulate the moment you start it up never allowing it to get up to operating temp let alone overheat lol