Thanks for the replies, but I am on my second part and they both do exactly the same thing. the guy I bought the part from said there are no seals or gaskets inside that part. And the valve works proper when it's supposed to send vacuum to the heater valve in the engine. there is no sound at all, no leaking. it's when you move it to cold, it dumps the vacuum (or more accurately, is probably sucking air in) through the connection point making a noise. I can't imagine two parts are bad. what is really weird is that you'd think this would be a parts bin part and multiple GM's would use it, well they do, but not this exact design. it's unique to 69 Firebirds. I can't tell you how many parts are unique to this car. I will try the oil thing, but something just seems weird here. you can see in the one diagram that there is a part on the travel of the valve where it's not sending out vacuum to the heater valve and it's quiet holding pressure inside (I've tested this with a vacuum pump). but that area is not where the pin goes on cold, it goes in the opposite direction and dumps the air. I know the sound can't be right, but two bad parts? just seems odd