I just fill the radiator thru the cap and have the tube to the overflow bottle plugged

 

Hey Steve. My take on it...On our "closed system" renix, it's not really so much an an overflow reservoir, but an expansion tank. Since water won't compress, and air does, we we leave that 1/2 full of air. That then, can compress when the "contents" of the cooling system expand. Theres gotta be a little give somewhere or the pressure could skyrocket.

In the normal, open system, there is a spring in the cap that holds the coolant pressure. When there is too much, coolant goes past the cap onto the overflow reservoir. Later when it cools that makes a vacuum in the system which then draws the coolant in the reservoir back into the system.

On my Jag/Chevy 350 conversion I just have an "in line" rad cap, on a large upper hose. I stuck the tube for the recovery tank in an old oil jug that fits in there at about the right height. (tube needs to be at the bottom so when it sucks it gets fluid and not air). Drove it that way a couple of years. I had allot more trouble with cops than I did with that funky recovery tank!

 

stev-o, your 89 radiator has a cap?

 

Yeah it was replaced by the previous owner I'm assuming

 

I read it wrong. Thought you plugged your hoses to where the bottle was..... So yea, you might want to find a recovery tank and run the overflow tube to it for hotter weather. I've never checked out a newer Jeep, I assume it uses the normal, old system.

 

Gotcha, Stev-o I was like "What the hell... that'd make life a little easier." good luck, and replace it. shouldn't cost all that much, and 1 less thing to worry about.

 

Ok, so I run the jeep, and the rad cap pops right off. Looks like I need that Volvo cap. Also, I need a new overflow tank, because thats just acting wierd. I think those 2 would solve the issue. The soon to be new owner will take care of the shroud.

 

Good plan. The Volvo cap really helps. Is the bottle cracked or is the cap just not holding on it well?

 

on my cap i just bent the two tabs that hold the cap on so that it held the cap on a little tighter

 

You must not have the original Renix closed system then.

 

X2 on that. and Cruiser, the cap is just not holding well. My jeep was at 210, idleing and then start getting warmer, I looked under the hood, and sure enough, and I said to myself "This is where cruiser says Told ya so" lol, the cap was loose. didn't pop off this time, but just definatley got pushed past the threads. The OEM like I bought aren't even fully threaded, its for equal sized spots that have threads. I am not sure if I need to get a new coolant tank, or just the volvo cap, but I need to do something. I let it cool, and ran her again, with the hood up, and all seemed fine, and i was checking the temps, and when it got to running temp, it seems to build a pressure in there, and just pops the cap up a few threads, lets air get in, and starts to boil almost instantly. I am 98% sure now that the cap is my continuing issue.

Any thought after all that Cruiser?

and for Steve-o- The cap we are talking about is all plastic, and does not go on the radiator. The Renix engines have a closed cooling system, which, If I understand what everyone says, in comparison to my jeep, means that instead of having a cap on the radiator, our cap is on the overflow tank.no cap on the radiator. Yours seems to be the nexer version, because it sounds like you are talking about the metal cap on the radiator that can is held on by the 2 nipple things, and allows for some adjustment with in them.

 

up grade to open system and never look back

 

Why? Nothin' wrong with the RENIX cooling system, it's just as sensitive to maintenance as the later system.

Out of the five RENIX rigs I've had, the one that ran hottest was the one with the conversion done on it. By about ten degrees, by the time I was done with it (I bought it converted, but it didn't look like anything was done wrong. I just couldn't pull the temperature down on it as far as I could on the other four.)

 

Try just the Volvo cap. I've seen it work without changing the bottle.

Unless the bottle looks particularly skanky and you feel it's gonna fail soon anyway. Try the cap for a few days and see what happens.

Oops, had to edit my post at the last minute to add this: "I told ya so". LOL.

 

Thanks, smartass. lol. I appreciate it. I am assuming itll more likely work with just the cap. I am getting ready to trade my cherokee, after all the work I have put in it, and just need to get this solved. I am leaving to Florida on monday, but I will post with just the Volvo cap and see what happens, and post back.

Thanks for the advise.