closed to open cooling system

[Maveric]

how do you convert a closed radiator/cooling system from a 1988 comanche to an open system like my dads 91 cherokee? how hard is it? got to replace my radiator anyway its heating up but radiator is cold as ice, tried flushing and everything, nothing else is working, figured now would be a good time for a project of this kind, what parts will i need? how hard is it to do? please any info would be greatly appriciated, i need help guys!

step by step instructions as I'm not familiar with the system.

 

thanks in advance for all your help, lets keep one more comanche on the road y'all!

[BLHTAZ]

I have a couple ditfferent threads on here about the change. I will tell you that had I known what a PITA it was going to be, I would not have done it this way.

 

Here is my thread about the biggest PITA of the change... the electric fan operation... http://comancheclub.com/forums/viewtopi ... conversion

 

Here is my thread on the conversion itself... http://comancheclub.com/forums/viewtopi ... conversion

 

 

Replace your radiator with the same style and then look here for a very detailed write-up about using a Moroso Expansion tank to achieve the same effect without all of the other issues I went through... http://www.markashurst.com/Jeeps/Moroso/

[MiNi Beast]

Nice write up in the Do it your yourself forum...

http://comancheclub.com/forums/viewtopic.php?t=7695

[dakal]

i have a 88mj with the i6. when i did my conversion, there wasn't a electric fan. i'm still thinking about which way to convert it. one fan, two fans, with removing the mechanical fan and the extra pulley crap. the conversion from closed to open or open to closed wasn't hard. i bought a new 91+ radiator. i have the old top radiator hose. would like to shorten it. any ideas along with autozone part #? engine bay looks a lot better. worth the effort just for that. good luck

[BLHTAZ]

i have a 88mj with the i6. when i did my conversion, there wasn't a electric fan.

:hmm: I have not seen one without and electric fan. Do you have AC...maybe the ones with no AC are without a fan??

 

Anyway...I know there are easy ways to make the fan work with a manual switch, but I wanted it to work the way it was designed so it was a real pain to figure out and definitley not worth the effort.

[maddzz1]

i have a 88mj with the i6. when i did my conversion, there wasn't a electric fan.

:hmm: I have not seen one without and electric fan. Do you have AC...maybe the ones with no AC are without a fan??

 

Anyway...I know there are easy ways to make the fan work with a manual switch, but I wanted it to work the way it was designed so it was a real pain to figure out and definitley not worth the effort.

 

Taz, If you don't have AC there is no electric fan. I don't have AC and just have the mech fan

[Maveric]

part one 91 or newer radiator for open system, part two over flow bottle from a 91 or newer, i got an electric fan already do i need to mess with that? it never seems to come on, and i have no AC :dunno:

do i need a new water pump? i think this one still works, just think my radiator is clogged up, so all in all

 

1) 91 open system radiator

2) 91 over flow bottle (have to move coil?? what coil?)

 

what else? thanks for the help so far guys, i hope to get this fixed soon, i got to move my girl down here and thats a nice 500 mile round trip fully loaded 250 of it, and its mostly nothing between there and here, id hate to get stuck and its my only vehicle.

 

Jeep on Y'all

[BLHTAZ]

A new water pump is not required, but mine had a very small drip coming out the bottom so I chose to do it at the same time. If you are going to go through with it, you will need...

 

- '91 & up Radiator

- '91 & up heater hoses

- '91 & up heater control valve

- Some kind of overflow bottle (I chose a generic one from the autoparts store)

- Some hose to run to the overflow

 

You could also do away with the heater control valve by going with the '97+ style heater hoses that run directly to the heater core.

[Maveric]

so a trip to the junk yard is in order? for the overflow bottle/heater hoses? and skip the heater control value? this is all quite new to me, this being my first car, so bare with me, so i need to do what?

 

i guess i could get heater hoses from an auto parts store, and whats the coil that id have to move near the bottle for the 91+ overflow bottle to work?

[BLHTAZ]

The pic below kind of shows it all. There would normally be a heater control valve in the area of the yellow circle, but in this pic the heater hoses go directly to the heater core with no control valve as shown by the red circle. It also shows where the overflow bottlwe mounts, but on your Jeep there is some electrical stuff there, including the ignition coil, that would hve to be relocated. Mine has the same set up so I chose a generic bottle from Discount Auto Parts and mounted it on the firewall where the old pressure bottle used to be.

 

 

 

This is a typical set up with a heater control valve...

 

[HOrnbrod]

The pic below kind of shows it all. There would normally be a heater control valve in the area of the yellow circle, but in this pic the heater hoses go directly to the heater core with no control valve as shown by the red circle. It also shows where the overflow bottlwe mounts, but on your Jeep there is some electrical stuff there, including the ignition coil, that would hve to be relocated. Mine has the same set up so I chose a generic bottle from Discount Auto Parts and mounted it on the firewall where the old pressure bottle used to be.

 

 

Hey! That's my picture you dolled all up! But it looks much better now. :cheers: As far as the fan controller, I decided to use the Spal variable speed unit for my 2nd (main) electric cooling fan. It runs the fan either at low or high speed depending on the LOW/HIGH temps you program in yourself. Sensing is accomplised either with the existing sensor in the stat head, or the temp gauge sensor. I used the temp gauge sensor and it really works well, exactly as advertised.

[87ComancheLB]

i have a 88mj with the i6. when i did my conversion, there wasn't a electric fan.

:hmm: I have not seen one without and electric fan. Do you have AC...maybe the ones with no AC are without a fan??

 

Anyway...I know there are easy ways to make the fan work with a manual switch, but I wanted it to work the way it was designed so it was a real pain to figure out and definitley not worth the effort.

 

Taz, If you don't have AC there is no electric fan. I don't have AC and just have the mech fan

 

My 87 came with a electric fan, but no AC.

[BLHTAZ]

Hey! That's my picture you dolled all up!

Yea...had to do a little search, but I knew it was here somewhere ;) :D .

[dakal]

mine has no ac. :USAflag:

[djag12]

I have no AC and mechanical and electric fan. FYI

[Vandenborg1]

Ok so I'm probably going to do thus conversion but on the radiators for the new models they all come with the transmission cooler in them do i need to cap them off with the manual or just leave them be?

[Eagle]

You could leave the tranny cooler outlets open, but that's an invitation for bugs to nest. Just plug them.

[Vandenborg1]

Perfect thank you

[PIKE]

Mishimoto makes an aluminium radiator that has 

• Provision for the older-style temperature switch and a filler neck with a pressure cap for open or closed cooling systems.

https://www.mishimoto.com/jeep-cherokee-xj-aluminum-radiator-1989-2001.html

• The expansion bottle from a 2.5 works well. Bolts right in, the holes are there.

If your radiator is good you can go with the Macs aluminum tank instead of the plastic one. It has a regular radiator cap to convert to open system. Very easy. Use the 2.5 expansion bottle with this too.

[omega_rugal]

wait, why do you want to switch to open system? do you have overheating problems?

[Vandenborg1]

Yes I have overheating problems 

[omega_rugal]

On 5/26/2008 at 1:57 PM, Maveric said:

got to replace my radiator anyway its heating up but radiator is cold as ice, tried flushing and everything, nothing else is working

 

mmm from what i understand, the engine is overheating but the radiator is cold, then you have a coolant flow problem, maybe the water pump is dead, have you check that?

[cruiser54]

NR2802 from Napa will go right in and give you open cooling system.

[omega_rugal]

or get one of these

 

 

put it in the upper radiator hose

 

and don't kick yourself over the overflow bottle, it can be installed anywhere but the closest to the coolant cap the better, and any bottle does the job, mine has a pepsi cola bottle  and i don´t bragg about it

 

 

[PCO6]

Perhaps a dumb question but I'll ask it anyway.   Apart from eliminating the heater control valve, what is the main reason for converting from a closed to open system?

 

I have a '88 MJ and a '89 XJ, both with the original closed systems.   I have no cooling issues with either.  The XJ has AC (2 fans) and the MJ does not (1 fan).   I've driven both all day long in hot weather at highway speeds and at times in stop and go traffic.  I maintain both systems (coolant changes, flushing, hoses, belts, pumps, etc.) in stock form.  The only thing I don't like is not being able to pressure test them.

 

Both run a bit different.   The MJ stays at 100* (212*) and doesn't move.   I'll probably be adding a stock Jeep electric fan to this one.   The XJ is always a bit below 100* but it fluctuates which I take as the electric fan kicking in or the thermostat (MOPAR) opening and closing.  I tow a 1,600 or so pound tear drop trailer with the XJ and all is good. 

 

A lot of what I read says "do it" but I can't see making the change when all is good.   Maybe I'm living on borrowed time and should move this up on the list of things to do.