Am I headed in the right direction? Cooling Problems.

1st time poster. I have a 1990 (closed cooling system) AT, 4wd, 31"tires, 140,000 miles, fresh fluids through out.

It was running "fine" but at 240 deg. I researched and found that others said that they run hot and was fine. One day it boiled over ( under the cap) going up a hill. I stopped, let it cool, topped it off drove home stayed at 190.

I then flushed the system (10min flush). Replaced all hoses, belt, T-stat/housing, fan clutch. Jacked up the back, removed the temp sensor filled with coolant closed everything up and took it for a drive. It ran at 190 deg on the freeway, up hills, and around town until I shut it off. After it was shut off it start boiling over from under the cap.

So i bought a Dorman replacement. And that is where I am now. The new bottle still leaks and I am over heating going up a hill.

So I guess my two problems are bottle not holding pressure and overheating going up hill.

As far as the bottle goes is it normal for the overflow to fill to the top after the XJ is shut off?

And the over heating, I think is a problem with the electric fan. It will come on with the AC but only randomly comes on if the temp goes above 210.

Any input is greatly appreciated.

have you verified your temps with an IR gun?

Yes, the overflow bottle will fill to the top, it is a pressurized system. Its difficult to remove all the air bubbles from the system, but using a Volvo Station wagon cooling bottle cap may solve some of your problems. To get rid of the bubbles I have found it works to run the engine up to temp, let it cool, fill the bottle, run it again, and over and over until no more boilover occurs.

I highly recommend the Volvo station wagon cap though, it is rated for slightly higher pressure.

Thanks for the quick responses.

Yes I have verified with Ir gun.

XJ Vis do you have a part number or a year make model range?

Get a known good bottle and cap.
Replace the radiator (esp. if its a cheapo thats at least 5 years old. One or two big wide cores is better than 3 small cores. )
replace fan clutch.
bleed system a few more times.

Replace water pump. like 30$ new at Napa.
You need to bleed the air out on the system.More than likely you didn't get it all the first time.
Wire the e-fan straight to a switch in the dash so you can turn it on whenever.
make sure the radiator is not plugged in the fins or internally.
make sure your fan clutch is working.

Ok I'm going to bleed it some more. Do I need to burp it from the temp again?

Forgot to mention that the water pump is new.

If it's the radiator I'll just sell it. Bought the XJ for a grand. It's just a fish truck so there is no strong attachment.

Just burped it three more times. Clutch fan is new. When I try to spin it I can feel a little resistance. Very little but definitely not just free spinning.

After I initially installed the new fan clutch. It would clime hills easily. Can it fail from over heating? Or is it likely I got a bad one as well as a bad bottle?

I'll save you a bunch of time and headache.

buy a 91 radiator and cap. Don't get the later model ones because they had a higher pressure cap.

buy the generic coolant bottle from autozone, it will fit behind the airbox on the drivers side attached to the fender perfectly and has a molded in dip tube.

Buy 91 heater core valve (or delete that mess and cap the vacuum line, you've got a blend door)

install parts, enjoy a self burping cooling system that just works without fuss or second thought.

edit: and your cooling fan switch is inthe radiator, it won't work unless the radiator is actually full. I've seen the open radiators come with or without the port. If it comes without, buy HO water neck that has the hole for sender, install GM temp switch in water neck and relocate sensor wire to t stat housing.
I spent 3 years fighting the closed coling system, a few hundred dollars in parts ad you won't mess with it for years to come.

Just an FYI, rock auto has a 1.5" single core open system radiator for like 80$ I think. Thats pretty legit.

Radiators are not that expensive and easy to swap.

Yeah I guess I'll do the swap. Although I would get immense satisfaction in calling in an artillery strike on this thing.
I had a 01 xj it had a cracked head. Now this one is got this going on. Note to self "buy a 97-98 next time ".

Thanks for the info everyone.

In my 1st 87 XJ, I spliced one of these

into the upper radiator hose, bypassed the whole coolant valve mess and mounted a generic overflow container in the same area I removed the "football" from. I think it cost me less than $80 total and it greatly reduced my cooling system hassles in about an hour.

dakinejb said:

Yeah I guess I'll do the swap. Although I would get immense satisfaction in calling in an artillery strike on this thing.
I had a 01 xj it had a cracked head. Now this one is got this going on. Note to self "buy a 97-98 next time ".

Thanks for the info everyone.

Click to expand...

after you do the swap you'll not touch it for 5 years.

I love the renix, the closed cooling system was the only downside. Ditch it and you will have a reliable DD that's hard to kill. In fact I'm going back to a 90, and when I pick it up 3 states away I'm swapping the cooling system before I drive it home.

Closed systemscan work fine too. All Crown Vics, Marquis, Town Cars have them without issues. Also Mercedes & BMWs. Get a better bottle and cap and you'd be good.

Well here is where I am at now. After a few beer I started thinking (usually how it works). Could the over heating be to the belt being to lose causing the fan to slip?

When I replace the fan clutch I was able to turn the fan over by putting a wrench on the crank pulley.

Today I "tested" the fan clutch. 1st I spun the fan by hand with the motor cold then with it at operating temp and fan spun the same. I then ran it again at temp, shut the motor off and the fan continued to spin for a few second. Shouldn't stop with the motor at temp?

So then I pulled the Fan clutch and when I tried to turn the crank over it just spun with out moving the belt.

When I put the new belt on I just guessed at the tension. I have read that you tighten it so the it turns half way or vertical.

So today's questions are how tight should the belt be? I have very strong hands so my ability to turn the belt is going to be greater than the average Joe. And is the fan clutch bad or will a lose belt produce the same results?

note that the motor has been severely over heated with the new fan clutch on it. It had zero water by the time I got it home. And yes I tested compression 130-135 through out all 6 cylinders.

you'd have issues with the alternator slipping before the fan did.

If your system is not holding pressure you will not get it to work properly.

I got a new cap. It's Holding pressure now.

Now I'm trying to solve the over heating going up hill problem. I am unsure if it's a bad fan clutch , lose belt, or e - fan.

you should not need an E-fan at highway speed.,

any fan at highway speed for that matter.

is the radiator original? If so I will nearly guarantee that it needs replaced.

again, just go buy a 90 dollar radiator and replace it. You've already severely overheated your motor troubleshooting this. Is it worth lunching your motor over an 90 dollar radiator you can get at any parts store?

Why spend $90 if it's just an adjustment needed? The fan clutch is still under warranty and is only 4 bolts.

have fun wasting time.

You've replaced every component in the system BUT the radiator, you still have overheating problems at highway speeds, the situation in which your cooling system is taxed the least. What do you suspect the last culprit in your cooling system may be?

You have a coolant flow problem. It's either hoses or the radiator.
But what do I know, I only owned a renix jeep for 8 years, another 87 that got daily driven for 2 years and now an 01 that got it's whole cooling system replaced too.

Sorry not ready to drink the cool aid yet.

Not sure where you got the highway speeds idea. The problem is going up hills.

I really due appreciate the input. But I would prefer to spend as little as possible on this thing. I'm going to exchange the fan clutch. As I stated before it's still under warranty and from what I can tell is bad.

I dont doubt your knowalge but like they say in Kentucky "there is more than one way to sleep with your sister"

Again thanks for the input and after I eliminate ALL other possibilities I will TEST then replace the radiator if it's bad.