Hey I had a dead battery so I jumped it and got it running. I let it run for about 10 or so minutes to make sure it was charged up. Well I was talkin to someone and I look behind me n it's steaming all over, the therm was in the red so I killed it. But n hour later I start it and it's right back at the 260 mark. Any ideas why it won't cool down?

 

Your gonna have to go through the entire cooling system. Might of been a tstat that failed closed or the mechanical fan dosnt work, air bubbles ect.

 

Which list is shorter.....what has been done or what hasn't been done, with regard to maintenance. Post the short list......less guessing with the short list.

 

I haven't done anything to it, I replaced the antifreeze a little bit ago and haven't had a problem except for this morning. I'll prob just replace the tstat cyz it's only 10 bucks for my jeep. Then if it still does it get a new radiator.

 

If u guess at and replace one cooling system component at a time, u've got to drain/re-fill coolant each time u replace something. Since no maintenance has been done, why not bite the bullet and spend a Saturday/Sunday afternoon (while the parts stores are open) and get 'er all done at once..

 

I think I figured out, couple weeks ago I bought a reserve tank for it, noticed the cap does t seal so it's evaporating right out. I took your advice and went to go to the auto part store. It died on the way there. So I had to walk a couple miles, got two bottles of coolant, tstat and another reserve tank. I put the two bottles in first so I could get home/ store, it ate it right up. So it must of the tank not sealing letting it out, it was enough to get me to home were I can use a different car to go get some. Hopefully nothing happened when It stalled out :/

 

Is it a renix system?

 

Yes it is. I found out what the problem was, letting it run ran it hot because the cap was bad not letting any pressure build up to raise the boiling point so it boiled and steamed away. Fixed that, the tstat and refilled it and no everything's good

 

Ever thought of converting it to the 'open' coolant system

 

As the previous post says, convert to the "open" 91+ system. I had the same problem with a 1990 I had and it literally KILLED my engine! I kept chasing the problem around like an idiot. The real problem with the closed systems on the Renix 4.0s is that no matter how hard you try or how many times you do it, you will never be able to completely rid the system of AIR. Air bubble in system = blockage that moves around but allows things to get WAY to hot. As this happens the stupid little bottle does nothing but fail and you toast your engine!

The only plus to all of that was that I got to replace my engine with one I rebuilt that really kicked ***! Too bad the computer fried two months later

 

How do I convert it to an open system?

 

Even with an "open" system, components go bad when neglected (ie., rad cap) and the end result is an overheat.

 

Yes but it also allows the motor to breath better and is a lot less hassle. Plus with a closed system there no way to get every bubble out and I've learned from experience.

 

To convert to open..
-Radiator
-coolant tank
-hoses and I also did tstat and housing for it off h.o

 

I never have quite understood the burping issue on the "closed" system. From the posted pics I've seen, the bottle is located up high so air in the system should naturally migrate to the bottle as coolant circulates, no? Aren't the radiators (closed and open systems) virtually identical (except for the caps)?