• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Open System: Yay or Nay??

i could be totally wrong, but im pretty sure the 95's were already a "open" system.

I used a 94 radiator to convert my "closed" system renix to "open"
 
95 is open system, properly burped and clean closed system is much more efficient (that's why most newer cars used a closed system ;)
 
So you've heard that an open system conversion is a good thing, right?

...and now that you know you already HAVE an open system you want to know about converting to a closed system??

Why would you turn back the clock on your Jeep?
 
95 is open system, properly burped and clean closed system is much more efficient (that's why most newer cars used a closed system ;)

Gee, I don't know maybe because of this! I don't know Grimm personally but I know he is well rounded in the XJ arena. My 1st XJ I converted to V8 and ran it till I couldn't get it smoged any more. So I transferd the axles to my 95 in 2008 which I've had since 2000. So with big axles and tires I need to make the cooling system more effecient.
 
What would it take to make it closed, is it worth it, would it be more efficient, or not enough of a differance to matter?

not enough of a difference to matter.

You'd need:
Different heater control valve.
closed system radiator
surge tank
 
My 88 is closed and works fine in the SoCal heat. If I were you, I'd leave it open.
 
95 is open system, properly burped and clean closed system is much more efficient (that's why most newer cars used a closed system ;)

I am in total agreement!!!!
 
FWIW, mine is a Renix closed system, 87, with an open system inline filler cap on it. The filler cap (radiator style cap) never opens because the closed bottle with the air bubble keeps the operating pressure way down. The closed system runs at about 1/2 of the internal pressure that an open system runs at. The Coolant is not exposed to O2 and CO2 from the atmosphere which ages the coolant faster than in a closed system.

Cooling efficiency does not care if it is open or closed. But coolant age and scaling the tubes up does affect efficiency over time. I believe the open systems scale up the radiators tubes faster than closed systems. That is why I stayed with closed systems. And most cars since OBD-II are closed systems, with better bottles than the Renix bottle.
 
efficiency of the coolant may not care if the system if open or closed but the pressure of the closed system raises the boiling point of the coolant allowing it to transfer more heat away from the cylinders without boiling over than an open system, which is why most renix rigs sit between 180 and 210 and all HOs are happy at 210. the bottom line is a closed pressurized system will always run cooler (if operation properly obviously) than an open vented system.
 
Looking at making the cooling system on my 95 XJ an open system. Any thoughts, experience, actual documented temperatures????

Your 1995 will have the "open" system OEM - it was only used on the XJ 1987-1990 w/AMC engine (and maybe even only the 6-242, I'm not sure.)

However, neither system poses any specific problem to efficient function - most people who report lower operating temperatures after the converting from the "closed" to the "open" system do so because they've inadvertently corrected the actual problem - the service life of the OEM RENIX radiator (usually a Modine unit) runs 150-180Kmiles. The service life of an aftermarket Modine? I don't know, but I've put 200K on mine without incident. I have yet to ascertain any internal difference between the two, simply because I haven't torn them apart side-by-side for failure analysis.

Even the Jeep techs at my local won't use OEM radiators to replace - they go get either Modine or Performance Radiator units from the same shop I use, in fact.

I've had five RENIX rigs - the one that ran hottest was the one that was converted to an "open" system before I bought it (and I was seriously considering retrofitting it back to OEM...)
 
Back
Top