pete944

On the way up to the 944 Fest my car was running hot. I had a hose break at the Fest and thought that the reason it was running hot on the way up was that it was slowly loosing coolant. We fixed the hose at the Fest but it ran hot all the way home after that. Yesterday I did a permanent fix on the hose and noticed that when I squeezed the hose I could hear air hiss out from under the radiator cap. I had recently put a Stant radiator cap on it and that turns out to be the culprit. The new cap does not seal tight so the system was not pressurizing fully. That's why it was running hot (3/4 on the gauge) but not overheating.
I swear I'll never buy a cheapo radiator cap again.

led

When I replaced my cap I was warned about stant replacements. IIRC, they don't hold as much pressure in as the original cap.

Perry 951

Good to hear you found the source of the problem. We had great pressure when we got back to the house, if you recall... but it was also running pretty damn hot.

nine-44

Glad to hear you got a premanent fix on the hose and thanks for the warning on the cap. I had planned to get one because they have the nifty pressure release lever, guess not.

pete944

I'm sure the cap was the problem. I still had my old cap and I let the car idle for a while yesterday to bleed it and the hottest it got was just a hair over the 2nd white mark. It was getting to the 3rd mark with the Stant cap.
It ticks me off that I had to drive 180 miles with the heat on in 90 degree weather for a $3.00 radiator cap!

washington951

it IS amazing that a cap can cause crazy things to happen. i had a cap slowly go bad on me (real BEHR cap) - i would bleed the system and all would be good, then a couple weeks later, i'd hear the 'slosh' of water under the pass dash, fluctuating (not not dangerously high) temps and have to bleed it again....i'd also lose small amounts of coolant and couldn't figure it out. changed the cap (cuz i read on the list a while back that caps can be the problem) and viola - no problem now!!