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Cooling conversion

homebrew

homebrew

NAXJA Forum User
Location
Bremerton, WA
hello all. I live in hawaii right now, soon I will be moving back to cali. My dad is giving me a 88 XJ with a closed cooling system, just wondering how hard it would be to make it an open system. can I just change the radiator??? what all would be involved???
 
homebrew said:
hello all. I live in hawaii right now, soon I will be moving back to cali. My dad is giving me a 88 XJ with a closed cooling system, just wondering how hard it would be to make it an open system. can I just change the radiator??? what all would be involved???
Click to expand...
I wonder why you want to if everythings ok? My 87 works just fine with the closed system. This thread would be a good place for the experts to explan whats better about an open system. It seems to me a good working closed system is better that a open system.
 
He just seems to have alot of problems with it, such as getting air in the system when adding fluid which causes it to over heat and to stall
 
homebrew said:
He just seems to have alot of problems with it, such as getting air in the system when adding fluid which causes it to over heat and to stall
Click to expand...
True but I said a good closed system, I change my coolent every other year and never have to add anything.
 
Ive heard that there is a bolt on the block that you can use to burp the system is that true???
 
I converted mine over years back. Pretty simple task. You can do it in a day. I read all the write-ups on the web and pieced together a parts list. Put the electric fan circuit on a toggle switch.

Yes. I could've kept the closed system and troubleshot my overheating problem but I figured I'd do the conversion seeing as I had to change out most of the required parts anyways. They were all defective or weren't there!

http://www.off-road.com/jeep/cherokee/98/12_dec/radiator/radiator.html

http://www.olypen.com/craigh/rad.htm

http://jeepsunlimited.com/xj/cooling/cool.htm

http://xjnation2.homestead.com/radiatorconversion.html
 
another question looking around it appears that the closed system was used up through 91. I have a 91 with an open system. would this be factory or a change from the previous owner???
 
I bought a 90 a couple months back...Ran hot ...Did the swap and never had a problem ...First mod i did .. resonable maintanance was not performed by the previous owners
 
tm999xxx said:
I bought a 90 a couple months back...Ran hot ...Did the swap and never had a problem ...First mod i did .. resonable maintanance was not performed by the previous owners
Click to expand...
My question is changing to a closed system did not fix the problem, replacing your cooling system with new parts fix your problem. A plugged leaking open system is no better than a plugged leaking closed system.
 
Yes you are correct...

I had to buy new parts anyway and didnt want to mess with air bubbles anymore.

I also read all the hype about switching over...I couldnt tell you which one is better. I agree, that if it "aint broke dont fix it"
 
to the thoughts on 91 being a closed or open i've not seen a 91 with the closed set up the 87 MJ,88 XJ, 90XJ I still have do my91 MJ and XJ don't
the main problem I've had is the plastic tank cracks every year or so. I've planned to change over to the open set up on the 90 for a few years haven't got around to do it though I just keep a spare plastic tank in jeep.
 
The 91 is open.

As far as "air pockets" in the closed system, I've really beaten this one to death. Properly maintained, there's NOTHING wrong with the closed setup - otherwise, why would more and more OEM's be using it?

If you never want to worry about air pockets again, simply drill two 1/16" holes in the thermostat flange, and install with one at 12:00 and the other at 6:00. Et viola! a self-air-bleeding system.

This is a good idea on pretty much anything with a thermostat.

The common consensus is that people who note a significant "improvement" after the conversion were probably coming due for a new radiator only - I've talked to a few ChryCo/Jeep techs, and the OEM radiators (all the way up to 1995 or so) were good for about 150K before they wanted replacing.

5-90
 
5-90 said:
I've talked to a few ChryCo/Jeep techs, and the OEM radiators (all the way up to 1995 or so) were good for about 150K before they wanted replacing.
5-90
Click to expand...

My '89's OEM radiator crapped-out after 12 years and 125,000 miles. Not too shabby for plastic radiator.

Installed all new hoses and waterpump last winter and ran fine but a little warm, but when first hot weather hit had overheating problems. Turned out the system needed to be purged. All is fine now and runs at proper temps.

To purge...jack up rear of jeep. Run engine until eninge heats up and slowly open temp sender on driver-side rear of head. Let air and coolent flow out. Close, fill coolent tank...let it bubble and purp and after it settles down open temp sender unit agian. Repeat until only coolent comes out of temp sender hole.
 
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