im still having a little prob with my coolant.
coolant systems stay highly presurrized after the rotors stop spinning, and this causes coolant to be compressed into the tiny gaps of the o-ring and into the combustion chamber.
i know everybody here has experience with opening a hot radiator cap, and i also know that there are some ventable type caps for cars.
my ? is, has anybody put a ventable cap on the filler and just vented a little highly compressed air out after a long drive to reduce the internal pressure? im not talking about scolding coolant all over your hand, but just a couple of seconds of leting air escape like opening a 2-liter Big Red.

 

anyone?

 

I have a 16lb ventable cap, but never tried to vent under hot and fully pressurized situations.
It sounds like you've got a distorted rotor housing and bad water seal, you sure you want to keep driving like that??

 

I would think that your problem lies with the O-ring, and not the pressure. Regardless of extra pressure, on a normal car, no coolant should go past the o-rings. Does your car show any other signs of o-ring failure?

 

If the coolants getting thru the O-rings you should be looking for a rebuild, not a new cap. Is it so bad that it douses your plugs?, if not just drive it....but it'll die sooner or later.

I had the same problem, and went 0 pressure to try to prolong the life of an already-overdue engine (117k) and it didnt matter.

Good luck.