CobraCon99
New Member
Hi,
This is my first time posting so let me know if this isn't the right place for this. I've got a 99 Cobra convertible with about 90,000 miles, stock accept for the Ford factory intake fix, a K&N air filter and some body stiffening (ladder sub-frame connectors, MM 4-point roll bar). I store it during the winter and start it up every once in a while to keep things from freezing up. The thing is after it's been idling for about ten minutes or so I'll get a thunk noise that sounds like it's coming from the trunk area. It's intermittent, so catching exactly where it's coming from is hard. I can feel it in the floor boards if I'm sitting in it. This also happens when I'm driving around in the summer. I've been having trouble filling the gas tank lately, which I believe is due to a clogged vent tube or charcoal canister, but otherwise can't think of anything else that could cause this. Is it possible the gas tank is heating up causing a build up of pressure that makes it thunk every once in a while? The only other forum posts I could find about rear end noises all pointed to suspension problems while driving. This noise will happen even if the car hasn't moved an inch.
Thanks!
This is my first time posting so let me know if this isn't the right place for this. I've got a 99 Cobra convertible with about 90,000 miles, stock accept for the Ford factory intake fix, a K&N air filter and some body stiffening (ladder sub-frame connectors, MM 4-point roll bar). I store it during the winter and start it up every once in a while to keep things from freezing up. The thing is after it's been idling for about ten minutes or so I'll get a thunk noise that sounds like it's coming from the trunk area. It's intermittent, so catching exactly where it's coming from is hard. I can feel it in the floor boards if I'm sitting in it. This also happens when I'm driving around in the summer. I've been having trouble filling the gas tank lately, which I believe is due to a clogged vent tube or charcoal canister, but otherwise can't think of anything else that could cause this. Is it possible the gas tank is heating up causing a build up of pressure that makes it thunk every once in a while? The only other forum posts I could find about rear end noises all pointed to suspension problems while driving. This noise will happen even if the car hasn't moved an inch.
Thanks!
