88 Xj 4.0. Previous Owner Got Rid Of Plastic CoolAnt Tank And Installed Metal Bottle With Rad Cap. Also Has Radiator Cap In Upper Hose. It Overheated A Few Weeks Ago So We Replaced Cap In Upper Hose With 12Lb Cap, Water Pump And Thermostat. After About 10 Min It Blows All Antifreeze Out Of Heater Hoses And Runs Like Crap....help

 

It can be tough to burp the air from the cooling system in an 87-90 Renix Jeep. One way is to let it idle till it starts to warm up, then shut it off and let it cool. Add more (50/50 coolant), repeat. The hole in the T-stat should be up at 12:00 to let air pass. In 13 years I've never needed to pull the temp sender or a heater hose, but indeed they can be stubborn!

Btw, leave that expansion bottle at least 1/2 empty, it needs air in there to compress. If it has a pressure cap...12Lbs seems a little low, 16 is more like it. Also it should have a recovery bottle with the hose from the cap ending up at the bottom of it.

 

It doesn't have the expansion bottle.......

 

Post a photo of the hose routing near the tank or better yet a shot of all of it.

 

+1 on the picture of the actual setup

From what I read I think:
By putting Rad Cap on the upper hose the cooling is converted to open system.
But there is still another metal container where the expansion bottle used to be, and this one has a Rad Cap as well, I think this one will need to be left uncapped, or with a cap that does not pressurize this second tank.

but again, we need to see the setup before jumping to conclusions.

 

^^^^This......an open system cannot have a pressurized bottle.

 

Yep. It needs to be one or the other. Combos don't work.

 

OK...Don't you have a metal bottle with a rad cap?

Agreed, a picture would be nifty.