755 Radiator Cap Question

[Pushrod_Paul]

Any JD 755 owners know what the pressure rating is on the radiator cap (e.g. 12lbs)?
Whenever I turn the tractor off, the coolent steams out through the overflow tube at the cap and drops the coolent level below the internal cooling fins. I'm hoping the problem is with the cap and I want to stop by an automotive store and buy the same pressure rated cap or one a few pounds over rating and see if that corrects the problem.

 

[Acehardly]

I have a 955 that does the same thing. It never drops below the fins though. If I don't fill it up all the way, It stops coming out. I do have pressure when it comes up to temp.
I'm getting worried that there may be something more than just a cap now.