AAAAAUUGGG!!!!!

[Akula69]

I have come to the conclusion that I will experience every single problem that can be experienced with a MJ. I had posted about the brakes earlier, but that problem has now been solved. Now....the problem Du Jour:

 

Now, the MJ is overheating on the highway (only). It will not overheat at idle or in the city, and it doesnt matter if the AC is on or not, it will go about 7 miles and then be at 280 on the gauge. I have drained and flushed the system, and have replaced the thermostat and the water pump. Thermostat was checked before install. I have "burped" the system as well. I suspect that the high volume water pump may be the culprit, because the only thing that I noticed with the system was when I opned the hood after is was overheated and saw that the bottom radiator hose seemed flattened.

 

When my son and I went through the engine we removed the upper and lower hoses, and I noted that the spring in the lower hose was falling apart (so I removed it). Now, when I check the parts stores I cannot find a hose with a spring in it.

 

Does anyone have a source for the bottom hose with spring, or for a hose spring? I have even called Gates (supplier for the parts stores in this area) and they no longer manfacture a hose with a spring.

 

Also, how many of you have retained the closed system but replaced the 1 row radiator with a 2 or a 3 row, and has that worked for you?

 

as always, thanks for your replies!

[1987Comanche]

Disconnect your electric cooling fan and go for a ride on the highway. If it comes on at speed (50mph+) it may be blocking air trying to go across the rad.

[shark]

finding a spring should be the easy part.

http://www.google.com/products?q=radiator+hose+spring

 

you said you changed the water pump. was it a high flow pump before and after?

[gl1200aman]

did you get the right water pump? others have mentioned that there are a clockwise and counterclockwise pump.

[Akula69]

finding a spring should be the easy part.

http://www.google.com/products?q=radiator+hose+spring

 

you said you changed the water pump. was it a high flow pump before and after?

 

I do not believe the old pump was hi volume. The new one is.

 

did you get the right water pump? others have mentioned that there are a clockwise and counterclockwise pump.

 

To the best of my knowledge it is the correct pump. If it was not, wouldn't it be overheating at extended idle and in the city driving as well?

[Akula69]

Disconnect your electric cooling fan and go for a ride on the highway. If it comes on at speed (50mph+) it may be blocking air trying to go across the rad.

 

I have the stock electric fan (which sits behind the radiator)so I'm not sure how it would affect the airflow across the radiator fins. I don't have any items in front of the radiator (except for the condenser). I have checked the radiator tank switch and it does make the fan come on at around 220 degrees, even without the AC on.

[Eagle]

I suspect that the high volume water pump may be the culprit, because the only thing that I noticed with the system was when I opned the hood after is was overheated and saw that the bottom radiator hose seemed flattened.

Very observant.

 

That's your problem.

[Garvin]

I had a high flow water pump in my '90 Cherokee and didn't have an issue, don't see that being the problem.

 

Definately change the lower hose and put a spring in it. After a while, the hose starts to degrade and won't hold it's shape when pressure is put on it, causing it to collapse. The other thing to check is make sure the fins in the radiator aren't clogged, I had an issue on the highway that it would run warm because of that.

 

Is the Jeep lifted/running larger tires? If so, then I would suggest a larger radiator due to the fact that you need a higher RPM to spin those tires at highway speed.

[Akula69]

I suspect that the high volume water pump may be the culprit, because the only thing that I noticed with the system was when I opned the hood after is was overheated and saw that the bottom radiator hose seemed flattened.

Very observant.

 

That's your problem.

 

Thanks, but what I was hoping for was to find out if others had suffered this problem, or if it was unique to me because I had put in an after market high volume pump (I knew the flattened hose was a problem 8) )

[Akula69]

I had a high flow water pump in my '90 Cherokee and didn't have an issue, don't see that being the problem.

 

Definately change the lower hose and put a spring in it. After a while, the hose starts to degrade and won't hold it's shape when pressure is put on it, causing it to collapse. The other thing to check is make sure the fins in the radiator aren't clogged, I had an issue on the highway that it would run warm because of that.

 

Is the Jeep lifted/running larger tires? If so, then I would suggest a larger radiator due to the fact that you need a higher RPM to spin those tires at highway speed.

 

Not lifted, 205/75's are standard.

 

Drove it today after the flush and new antifreeze with a cooant additive (by Lucas products) that is supposed to make the fluid 'slicker'. Still tried to overheat at highway speeds, but nt as bad, and I got a lot more variation from the temp guage when the throttle was released at lower speeds.

 

I'm gonna get the spring for the bottom hose and go with a cdi 3 row radiator. We'll see how that works out the problem.

Thanks!

[dasbulliwagen]

A soft lower hose could be the problem, but iit could also be a clogged radiator. You may want to pull the lower hose off, and run a garden hose in through the top and see if youre getting good flow. if it backs up out the fill area, and dribbles out the bottom, you have a radiator problem too. good luck

[Eagle]

Thanks, but what I was hoping for was to find out if others had suffered this problem, or if it was unique to me because I had put in an after market high volume pump (I knew the flattened hose was a problem 8) )

Nope. Not due to the high volume pump ... but I'm certain that doesn't help. I was first clued into this problem by a fellow XJ owner down-state from whom I bought a set of OEM alloy rims about ten years ago. He had the problem, and he said it drove him nuts for about three months.

 

Once he noticed the collapsed lower hose, he scrounged a spring from a garage's pile of scrap radiator hoses, stuck it into his hose, and all was good.

[HOrnbrod]

4.0 lower rad hoses with the spring are still around, but not from aftermarket sources. There are still a few OEM hoses around from the dealer, about $20, at least for the HOs. Don't know if the Renix hoses are the same. With a hi-flow water pump (as I have) I'd never have a lower hose w/o the internal spring. I tried a Goodyear "reinforced" rubber hose for awhile - it eventually collapsed and caused overheating while in hi-heat traffic, so I crap canned and found an OEM w. spring.

[Comanche County]

I'll bet $100 on red --- (just needs a spring in the hose, you could make one if you had to - anything to keep the hose from collapsing)

 

But I'll bet $5,000 on black --- (you're radiator is clogged and a new one will fix it)

 

Let me know if I win! :D

[mkbruin]

I couldn't look at a hill without overheating in my 89 4.0

 

swapped in a GDI 3-core, never overheated again.

[Akula69]

After some research, (thanks for the post on the Mustang spring) I found an exact fit spring for the MJ bottom hose. Unfortunately, it appears in a hose for a 1970 Chevrolet pickup, and NAPA carries the hose as part number 7580.

 

Once you cut the hose open and remove the spring, it simply threads into the MJ hose from the small end without too much effort. It supports the entire hose except for about 2 inches from either end. THe hose will not collapse with it in place.

 

After re-install the truck did not overheat as quickly but still got quite hot (almost into the red zone after 20 miles with AC on high...97 degree heat with 90 percent humidity). I believe that was due to two problems - I had not completely bled the system of air, and it needs a 2 or 3 core radiator.

 

Thanks again for all the posts! :cheers:

[Akula69]

Picked up a 3 core csf all metal radiator on Monday and installed it today.

 

After 'burping' the system I drove it about 35 miles on the highway and it never got above 150 degrees on the gauge (ambiant temp outside was about 70 degrees)

 

I think I got it! :cheers:

[mvusse]

Check your thermostat. It should run between 180 and 210, with a 195 degree thermostat. 150 means either the wrong thermostat, no thermostat, or thermostat stuck open.

[dasbulliwagen]

Check your thermostat. It should run between 180 and 210, with a 195 degree thermostat. 150 means either the wrong thermostat, no thermostat, or thermostat stuck open.

And that will make the engine run rich and never enter the correct computer mode (closed loop, or open loop???), and could cause your converter to get hot and go bad. Put a thermostat back in it!

[Akula69]

Yes, I agree on the thermostat comments - I suppose I should say that I am guessing about the actual temp - looking at the gauge I am seeing the needle between the mark above 100 and below the 210 mark. Its about in the center of that range, and pretty much stays there.

 

Before, the needle would run right up to the 210 mark and hover, and when I hit the highway it would sprint up to the 260 - 280 mark.

 

I can tell that the thermostat is opening because the upper hose starts out cold and after about 5-10 minutes at idle it gets warm, indicating the 190 degree 'stat I have installed is actually opening (or is stuck open... :eek: ).

 

I'm gonna check it to ensure correct operation. Thanks guys.