Half Open Half Closed?

Ok having an issue with my cooling systems tried searching but can't quite find what I'm looking for. New to jeeps just bought a 89 XJ 4.0l and it seems to have an open style radiator with the cap on it but still using the the pressure bottle too. Started leaking at the cap on the radiator last night after just a 10 min. drive, didn't seem to be running to hot, around 210. Is it time to pick one system open or closed or should I just get a higher pressure cap think its a 16 psi on there now. Thanks

The closed system runs at a slightly lower pressure than the open system, so the fact that you're getting a bleed off from the open system cap (which should be a 16psi cap) is odd. I would suspect that the cap on the pressure bottle would begin to leak first since that is a 15psi cap. Could just be that you have a faulty open system cap on the radiator and that is all that needs to be replaced.

I would keep it as a closed system, replace the cap on the radiator and go from there. Consider yourself lucky that you have an open system radiator as it makes bleeding/burping the cooling system a lot easier.

If you don't want the open system radiator, can I have it?

Ok well thats good news cause my next question was if I should burp it, as I just flushed it the other day, I'll grap another cap and see what happens.