Burping the Renix Closed System

[Drahcir495]

There are so many “why is my Jeep overheating” and “how do I burp my  closed Renix system” threads on the Jeep forums that it seems it is a pandemic. The procedure is always the same; raise the back of the Jeep. Open up the coolant sensor on the back of the motor. Then keep adding coolant to the overflow bottle until the bubbles stop and it is level at top of the hole. Well,  I just had to replace my radiator and of course it had air trapped on the system. I raised my Jeep up in the rear as high as my jack stands would allow me and followed the instructions exactly on what I needed to do. I then ran the motor again to move the fluid through the motor just for  and . Then I just let it run and it overheated again . I finally gave up; I was done with it . I called Dee at Just Jeep’s to make an appointment to bring it in. He asked me if I had burped the system? If I had, how did I do it? He had a technique that I have never heard of before. In all my years of asking and searching on all the Jeep forums, here was an actual alternative to the jack up the rear of the Jeep pray.

 

Well, my mind is officially blow away by this! I am going to post this little gem on the Comanche Club so that anyone who is looking to “burp” a Renix motor will visit our community and realize how great we all are ! Enough babbling, on to the good stuff 
 

* The process is really simple.Take off the clamp on the small hose that’s attached to the thermostat housing  lol. Then pull the hose off the fitting. Open up the coolant “turtle” bottle and add water! I will explain why just water in a bit. You can just pour the water into the coolant overflow bottle, but I chose to do this with a hose to force the water through the system and expedite the process  ->

The opening on the thermostat housing will start to pour water out ->

Mine bubbled for quite a while. As soon as it looked like no more air was escaping through the hole, I put the hose back on. I figured that this way it would not run out of water and possibly take in air back into the system. This process is kinda the same as draining a fish tank with a hose; get the hose below the tank and gravity will work it’s magic . This is where using the water first becomes clear. Instead of just wasting good money on antifreeze to flush out the air, the water does most of the work. Now, take the hose off the outlet again and go back to the coolant overflow bottle and start adding your favorite flavor of radiator coolant. The antifreeze will actually push out the water. Just keep filling the bottle until the water is replaced with that sweet sweet green elixir . As soon as you’re  satisfied that nothing but coolant is exiting the block, just slip the hose back on and tighten it down with the hose clamp. Conclusion; it worked the first time and no more overheating 

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I can’t wait to hear how works for others with the closed system and that it was not just beginners luck.   
 

I hope this will be helpful - Rich

 

 

[ftpiercecracker1]

Interesting.

 

I always backed my truck up an incline, the steeper the better, then removed the temp sender in the far back, driver side corner of the head and filled the reservoir until no more bubbles came out.

[Drahcir495]

Not a lot of hills around here, so I used jack stands. Never got it to work . This definitely got the job done

[ftpiercecracker1]

Ya, its a PITA. Next time i need to do it i will definitely try this technique. Although I'm hoping to have converted to an open system before to long.

[Drahcir495]

I almost did the open system, but I never had any problems with the closed when it was burped properly. My XJ runs very cool, so don’t change what works I guess.

[omega_rugal]

leave the cap off overnight, rub the hoses ... that´s why i don´t like the closed system, there´s no advantage over the open system, it´s a pain in the @$$ to burp and any leak can lead to catastrophic failure

[Pete M]

the advantages are theoretical.  Higher pressure lets you run a higher temperature and a higher temperature allows for better efficiency.  Lots of different cars have a pressurized system.