Overheating after rad replacement

[AVR2]

So I finished replacing the rad in my KJ this morning, and I followed the FSM technique for refilling the coolant, which says to fill the bottle to the fill line, replace the cap and run the engine with the heater set to max. Of course, the coolant in the bottle disappeared within a short time. I took the Jeep for a spin and everything was fine for a few minutes, but when I turned on the AC, the temp gauge started to rise rapidly. I was able to stop well before it pegged into the red.

I suspect - hope - that because I only added one expansion tank's worth of coolant, there just isn't enough coolant in the system, combined with a lot of air. Despite what the FSM says, should I refill the coolant by running the engine with the pressure cap off, keep topping the bottle up as it empties, and wait until the air bubbles stop before replacing the cap?

 

[Ry' N Jen]

I suspect - hope - that because I only added one expansion tank's worth of coolant, there just isn't enough coolant in the system, combined with a lot of air. Despite what the FSM says, should I refill the coolant by running the engine with the pressure cap off, keep topping the bottle up as it empties, and wait until the air bubbles stop before replacing the cap?

That's all we did.
Just kept filling until the coolant level stayed the same in the expansion tank.
Then I just siphoned off the excess down to the full line with a huge syringe.
Probably not the correct procedure but it works.

 

[AVR2]

The FSM procedure did seem weird. I've read elsewhere that what you're supposed to do is remove the air bleed screw by the upper rad hose and fill with coolant through there, but I can't find any references to that in the manual.

 

[ridenby]

I used the bleed screw opening to fill most of system.

 

[AVR2]

I used the bleed screw opening to fill most of system.

So just to confirm, open bleed screw, pour coolant into hole until it spills out, replace screw using thread sealant? Should the engine be running while you do this? Do you need to burp it by running the engine with the pressure cap off afterwards? And is there a torque spec for the screw? As I say, the FSM doesn't even mention it in the cooling system section.

 

[ridenby]

I used thread tape when replacing it. Added water,engine off,slowly until full.Then replaced plug,and added coolant to the jug on fire wall-filled it pretty much,put the cap on and went for a ride. Next morning topped it off,checked often for a while.

 

[JeepJeepster]

No, do not run the engine with the plug out. You can but coolant will be all over the place. Ridenby said it pretty good.

 

[Luke]

I used thread tape when replacing it. Added water,engine off,slowly until full.Then replaced plug,and added coolant to the jug on fire wall-filled it pretty much,put the cap on and went for a ride. Next morning topped it off,checked often for a while.

^^^ That's how I did it .. last week.

 

[AVR2]

Thanks guys. Filled it through the bleed screw hole and everything seems OK now.