Odd Sound

I've been getting a strange sound from my truck. It happens a few minutes after shutting it off. Kinda hard to describe but it sounds like the puckering of a soda bottle only with a metalic tone, jsut a single pop. Anyone have a similar experience? I haven't narrowed down the source yet - it's one of those things I remember only whne I hear it and then it's too late. My mission tomorrow is to hunt down the source. Could it be the gas tank de-pressurizing?

good posibilty , but I think it might be your radiator cap sucking coolant from the reserve tank. Rob

hey those are all good possiblities that i never thought of , i do have the same problem but i believe its the muffler cooling down...

I haven't located the source yet but I do know it's not from the engine bay. I could only get it to do it once and as of right now I'm thinking it's the exhaust. I'll keep searching though.