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Thinking about converting my 90 to open system cooling

skyb44

NAXJA Forum User
I just picked up a 1990 2 door cherokee 5 speed 4.0. Runs great, but it leaks a bit of coolant from the radiator. It's the renix system so closed. I'm thinking that as the weather warms up I should probably update the cooling system.

seems a few renix zealots suggest sticking with closed. it seems that any leak in this system allows air in. I was thinking of going with a 3 row CSF radiator and converting to the newer style open system cooling. Any reason not to? Should only cost about 70 bucks extra....
 
I would think that not having to burp the system every time you fix something would be worth it but I've never owned a Renix so I don't know that much about them.
 
I converted my 90, I had to buy a radiator so it was just time to do it. The closed system was fine when all was going well but it just made sense to do it once and be done.

I used a 96 model radiator, a recovery bottle from Oriellys and dual XJ fans. You will not have the fan switch bung on a open system rad so you will have to work around that with a fan controller. I use a Hayden adjustable and it handles the two XJ fans easily. Cools it down fast yet lets you get quick warm ups on cold mornings.

Here is a pic, you can kind of see the overflow bottle and the dual fans

0206121346.jpg
 
When I did my 88, I picked up an mj 4cyl overflow tank. You need to shuffle some things around, but it mounts perfect on the driverside fenderwall.
2006_0322bottle0004.jpg


2005_0505selling0015.jpg
 
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thanks guys, where should i buy a radiator? The CFI is pricey, but I'd just as soon put a decent part in. this little jeep only has 149k miles on it so good for another 100 anyway right?
where do you get a second fan? I take it ditching the clutch fan is a good way to go?
 
The stock mechanical fan pulls more air than an electric fan will. Electrical fans seem to be more hype than anything. Just convert to the newer style cooling and go from there.
 
To do the swap RIGHT, IMHO, you need a 1992+ radiator...and no, 149K on an original radiator is pushing it and may be the source of any cooling problems you have.

The whole swap cost me a tad over $200. New hoses, cap, coolant of course, and I did not install either the heater control valve nor did I run the tranny lines through the radiator.

I also had to run a switch for the e-fan, I couldn't find a radiator with the temp switch bung. I know they're out there, but not for me. I also am using the ZJ HD fan (not MAX-COOL). Just use the same wiring and relay for the fan and wire the switch to the relay.

...and BTW, a 16 lb. radiator cap WITHOUT the little lever on it.

I did the 90 XJ after messing with burping, breaking bottles & caps etc. about 4 years ago. I did the MJ a week after I got it just because the XJ was working so well.
 
To do the swap RIGHT, IMHO, you need a 1992+ radiator...and no, 149K on an original radiator is pushing it and may be the source of any cooling problems you have.

The whole swap cost me a tad over $200. New hoses, cap, coolant of course, and I did not install either the heater control valve nor did I run the tranny lines through the radiator.

I also had to run a switch for the e-fan, I couldn't find a radiator with the temp switch bung. I know they're out there, but not for me. I also am using the ZJ HD fan (not MAX-COOL). Just use the same wiring and relay for the fan and wire the switch to the relay.

...and BTW, a 16 lb. radiator cap WITHOUT the little lever on it.

I did the 90 XJ after messing with burping, breaking bottles & caps etc. about 4 years ago. I did the MJ a week after I got it just because the XJ was working so well.


i meant the jeep had a ways to go at 149k, i'm fairly certain that radiator is on its last legs!
should i just toss an OE radiator in? they're about half as much money as an all metal 3 core....
when you say you didn't install the heater core valve do you mean you have no heat now? is the heater core valve hard to install?
this is a manual trans, so no tranny lines.
 
I put the CSF three row all metal in my 88 when I did the above conversion, they cool excellent. I also installed one in my 98, no problems with that either. Its been a while since I converted over the 88, but there are a ton of great write-ups on here to follow.

Lowrange: not sure about that on the 4cyl question. I got the info on the bottle in an old old thread, no idea which one. I ordered one up and it did fit nice.
 
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Swapped my '88 to a salvage yard '92 about eight years ago. Flush system out before install. Advice for overflow bottles in previous posts are good. Lever vent caps are easy to work with. Suggest you change out motor mounts real soon to protect the radiator.
 
I will take back what I said about the HAYDEN fan controllers, I just fried number 2 yesterday and the 4.0 got real hot but it made it home. I had the adjustable dual fan controller. Today I'm switching back the the "snap switch" and have it trigger two relays straight from the battery. I'm also going to add a toggle switch to override the snap switch just in case it fails.

The HAYDEN snap switch comes on at 190f and off at 170f which is about where I had the adjustable controller set at. Its a much simpler set-up than the complicated controller that obviously fried internally.
 
i meant the jeep had a ways to go at 149k, i'm fairly certain that radiator is on its last legs!
should i just toss an OE radiator in? they're about half as much money as an all metal 3 core....
when you say you didn't install the heater core valve do you mean you have no heat now? is the heater core valve hard to install?
this is a manual trans, so no tranny lines.

I have all metal 2-rows in both rigs. 3 rows...meh, probably not much better, I don't like the aluminum ones.

No heater control valve means that the coolant is alwyas running thru the heater core. The blend doors keep the heat out when I don't want it, in when I do and keep the coolant circulating all the time , lessening the chance of a clogged core. Plus it eliminates 4 possible leak spots plus the valve won't fail...it's not there!

When you buy a radiator they should ask you manual or auto...you'll likely get the same radiator...or one without tranny hookups.
 
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