howling help?

[BLAU DRM]

I have a 2003 996 C2 cab with manual trans and 17K miles. Sometimes while sitting at idle with the car in neutral, I hear a howling sound which appears to come from somewhere behind the gas filler door compartment. When I open the gas filler door, it REALLY sounds like it is coming from right behind it. I tried loosening/tightening the gas cap and that doesn't help at all. If I give it a little gas it goes away and sometimes the noise stops suddenly on its own...any thoughts? I can't remember if it only happens when it is cold or not.Thanks,Allan

[JFP in PA]

I have a 2003 996 C2 cab with manual trans and 17K miles. Sometimes while sitting at idle with the car in neutral, I hear a howling sound which appears to come from somewhere behind the gas filler door compartment. When I open the gas filler door, it REALLY sounds like it is coming from right behind it. I tried loosening/tightening the gas cap and that doesn't help at all. If I give it a little gas it goes away and sometimes the noise stops suddenly on its own...any thoughts? I can't remember if it only happens when it is cold or not.Thanks,Allan

Sounds like an EVAP system problem, which is located right next to the filler. EVAP is a vapor trap and recover system that uses vacuum to do its job; one or more of the vacuum lines or valves may be having a bad day.

Yes, I know the diagram is from a Boxster, but they are very similar setups.

[BLAU DRM]

HMMMMM.....thanks for the info JFP. I alreay have a slightly leaking rear main seal, so the more stuff I have to take it in for, the better use of my deductible...The problem is getting the problem to happen while it is at the dealership. Perhaps I'll video tape it when it is happening to show them just in case...don't know if that will work, but it is worth a try.

Thanks again!