as I have some struggle with temp ups and downs I checkt the t-stat again today.

drilled 2 small holes one at 12 and one at 6 o´clock as someone writes it is good.

I put up the back so the temp sensor is the highest point. I put out the sensor and bottle open.

I started to fill fluid into the bottle and the big radiator hoose until fluid comes out of the sensor hole. I put the sensor back in and filled up the hoose until the fluid comes out of the t-stat housing.

Then I put the hoose back on and started the Jeep. Tha bottle was still open and fluid was at the bottom.

the gauge shows the raising temperature but vary slowly. I did 3000rpm until it goes near 100 degrees. then the fluid comes out of the bottle

How much should be in when engine is warm. And how much when cold.

When I drive the temperature is between the first mark and the half of the gauge.

when i shot off the car the gauge raises to the point on the picture below...

 

Hi

I do have a Renix as well, but I convert it to open system.
While it was the closed system (original setup) and I had the need to burp it because of any repair, the procedure did not include the removal of any hose.
Basically I repaired whatever needed to be repaired, started filling with fluid on the pressure bottle, removed the temp sender to allow air to flow out, replaced it when no more air was going out, and fill the bottle cap to the middle, leave it open and started the Jeep, keeping an eye on the bottle and re-filling as need for a few minutes, then close the bottle and that's it.
If any air was still trapped, it will go to the bottle at some point in time, so it is good to keep a close eye to the bottle for the next few starts (do not open while hot).
after a few cycles there will be no air in the system, and you should still open the hood from time to time to check levels.

Hope this works for you

 

I'll just add that when I just recently replaced the radiator/hoses in my Renix, Idling was not cycling the fluid in when filled from the bottle - driving it around even just a few hundred feet, stopping, refilling, repeating a few times until it stays at the fill line is what seemed to work best. Just try not to overheat it if doing that.

 

This is not complicated.

1. Don't drill holes in the thermostat. You are sabotaging it. It won't be able to do its job.

2. On a Renix, just leave the bottle cap off. Run it at high idle for a while until you see the coolant start circulating through the bottle. Continue for 5-10 minutes like this. When you don't see any more air pockets moving through, cap it off. Drive and enjoy.

 

OP, my renix does the same thing. If I floor it the temp goes up. The engine produces more heat in a short burst and the t-stat can't open fast enough. Or something like that Be careful though, I've blown two hoses in a few months from this. They were old and probably original as yours may be too.

 

Just put the cap on and run it.

Check this out from the FSM

This system does not have a radiator pressure cap. Instead the pressure cap is mounted on the coolant pressure bottle. System coolant flows directly through a fully pressurized Hot-Type expansion bottle. Coolant flows through the pressure bottle at all times during engine operation whether the engine is cold or at normal operating temperatures.

Larger coolant volume caused by thermal expansion during engine operation is absorbed by the expansion chamber in the bottle. Air trapped in the system is purged through the pressure cap vent valve during maximum coolant expansion..

 

It beats me why some people are so afraid of a closed cooling system that they spend unnecessary time and money converting it to conventional.

Besides blowing the occasional heater control valve and pressure bottle, mine cools fine.

I took your advice and eliminated the control valve, with no noticeable side effects.

 

Eliminate the HCV and use the 703-1396 Volvo cap and you're good to go.

You made me think of something just now. Think it's possible the HCV being partially plugged, or a general restriction may inhibit burping?

 

How to eliminate the HCV? Will do when I know how...

 

Mine's not with me, or I'd post a picture of what it looks like after the conversion.

Maybe somebody out there will read this and post theirs, so you can see the hose routing.

 

I guess that would be me............'

 

For each one of these TRUE/CORRECT XJ cooling system statements, there must be 10,000+ FALSE/INCORRECT statements post on the Internet.

I will reemphasize "do not drill hole(s) in the XJ stat"......doing so accomplishes nothing other than slowing down the engine warm-up process and fast engine warm-up is important. Besides, there is a dime sized hole directly beside the t-stat anyway (the bypass) so why drill holes in the stat??????.....because some goober on the Internet says it's a good idea?....NOT.

 

I love how passionate you are about XJ's and maintenance in general, DJB. I really do admire it.

 

than I have to change the t-stat again and let it be as it is

I think I know how do burp the air off now Back up and sensor out, filling it in the bottle until it comes out, sender in. bottle filled to ground when the jeep is back on ground. start...

right?

 

No. Read my and Cruiser 54's post.

Replace thermostat. Fill. Drive. Monitor fluid level for a few hot/cold cycles.