upgrading a closed loop coolant system - JeepForum.com
LinkBack Thread Tools
post #1 of 4 Old 10-13-2009, 11:09 AM Thread Starter
Registered User
1999 XJ Cherokee 
Join Date: Feb 2009
Location: Sudbury, MA
Posts: 1,314
upgrading a closed loop coolant system

im looking to buy an 89 2 door, with the closed system. the coolant system needs some work anyway, and while im in there i was thinking of going to an open style. as far as i understand this, it should be as easy as ditching the radiator and pressure bottle, then putting in a newer style radiator with a cap that has the correct pressure. anything im missing? recommendations for a good radiator? thanks for the help.

Think Twice Garage
"Yeah, that might work, pass me the grinder..."
94ZJ AX15/HP44/8.8/5.13's/35'' MTZ's SOLD
99XJ 4.0/AW4/HP30/8.25 build coming soon...

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CTeunuch is offline  
Sponsored Links
post #2 of 4 Old 10-13-2009, 11:30 AM
Registered User
TheNerd's Avatar
2001 XJ Cherokee 
Join Date: May 2004
Location: San Diego, Ca.
Posts: 879
If you swap out the radiator, you will also need a coolant overflow bottle, a newer style ('92+ I think) heater control valve for the new piping, and will need to address the coolant temperature sensor (your sensor is currently in the radiator, where as the open systems use a different type sensor in the thermostat housing). Check the FAQ sticky... there are sever comprehensive articles on how to do this.

There are actually easier ways to to that as well that don't require all the new hardware (its all in the FAQ).

-2001 XJ Limited, 4.0L, NP231 w/ SYE, AW4, 4.5" Lift, 32" tires, 4.56's
-1987 XJ Pioneer, 4.0L, NP231 w/ SYE, NV3550, 4.5" lift, 4.10's, D44 rear
TheNerd is offline  
post #3 of 4 Old 10-13-2009, 06:36 PM
Registered User
2000 XJ Cherokee 
Join Date: Aug 2009
Location: Fairfax
Posts: 395
I chose to do this swap with all new components. I covered it in this thread (with photos on the last page): http://www.jeepforum.com/forum/f11/p...estion-834546/

There are a number of threads and other webpages with good advice on how to do this. Use the search function! And yes, as TheNerd said, you can use your existing system with a few mods, but I chose to start from scratch since all my components were pretty old and beat up.
oderalxjlaredo is offline  
post #4 of 4 Old 10-13-2009, 06:49 PM
Web Wheeler
Join Date: May 2005
Location: GA
Posts: 5,911
The bad rap that the closed system gets is almost entirely the fault of the failure-prone pressure bottle. Unless you actually need a new radiator, I would suggest that you consider a metal pressure tank. I put one on my '88 a couple of years ago and have had no problem since.
tangofox007 is offline  

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
closed loop mode temp Livewire94 XJ Cherokee Technical Forum 6 06-09-2010 11:06 PM
Adding coolant to a closed system... tgod XJ Cherokee Technical Forum 1 02-16-2008 01:05 PM
XJ Closed coolant system brycaroni17 XJ Cherokee Technical Forum 2 07-15-2007 12:37 PM
closed or open loop cygnus58 XJ Cherokee Technical Forum 4 07-05-2007 09:25 AM
thermostat change on closed system w/o draining all coolant? Digitalchaos XJ Cherokee Technical Forum 6 12-22-2005 01:55 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome