Exhaust Fumes in cabin

[eddieviv]

It's the darndest thing...

Re: 86' 944 Turbo...I can smell a slight exhaust fume in the cabin all the time but it's really bad when I have the driver's side window open even slightly or the windows rolled up and with A/C running. Can't figure out how it's getting into the cabin? I smell it LEAST when I've got the windows rolled up and I'm travelling faster than 60 MPH. I've had the car checked by the dealer, my regular really good mechanic, all to no avail. I've had the hatchback seal replaced to new, sunroof seal changed new and door seals new. Noone can can seem to find any leaks in the exhaust system anywhere. Confused...

[SD Porsche Fan]

Check the rubber insulation under the shift boot to see if there are any holes. If you have a leak in the tourque tube tunnel that might be the cause.

[eddieviv]

Steve,

Thanks, would of never thought to check there...

[jimbilly]

I just did some diggin into my S2 to find a similar problem. In my car it looks like the stock hose clamp goes kind of egg-shaped, and could allow a leak. I replaced the lower stock clamp with 2 aftermarket clamps, and the upper with one, it seems to smell better now. I think I still have a good likely causes link:
http://www.clarks-garage.com/shop-manual/ts-03.htm#fuel-smell

[nize]

this is a common problem. you should also check the rubber seals behind and above the rear passenger seats.

[myskyon]

ok i am getting this too but only at a stop or low speeds. it doesnt matter if the windows are down or up i still get the smell. so i am going to go over all of my exhaust clamps sometime in the near future.

[eddieviv]

In my car it looks like the stock hose clamp goes kind of egg-shaped, and could allow a leak. I replaced the lower stock clamp with 2 aftermarket clamps, and the upper with one, it seems to smell better now.

Are you talking about the clamps on the whole exhaust system itself? Sorry...Don't quite know what you mean...

[eddieviv]

This is a common problem. you should also check the rubber seals behind and above the rear passenger seats.

Thanks for your response! If this is a common problem there seems to be a lot of Mechanics having trouble finding the source? When you say the rubber seals behind and above the rear seats, are you talking about the rear hatch seal. It's one complete seal (one piece) and I changed it out already. No effect. Stiill getting the fumes aaarrrgghh. One Guy told me it could be fumes coming through between the rear hatch seal and the hatchback itself. He promptly adjusted the "catches' but again no difference....Then he suggested that I take the car to an Apple Auto Glass and have the whole hatch removed and re-worked. This will cost $1100.00 CDN, yet I don't want to spend this given no one's really sure???

[nize]

maybe the mechanics you're going to are not porsche-specific mechanics?

i was referring to the rubber seal above the gas tank inside the hatch area under the carpeting, although the actual rubber seal around the hatch glass itself (or the hatch not fitting properly and causing a reverse/drag air leak) can cause this problem as well.

this is a VERY common problem, and there are dozens of possible causes. check rennlist for them (search for: exhaust fumes).

here are just a few of the dozens of threads;
http://forums.rennlist.com/rennforums/showthread.php?t=270169&highlight=exhaust+fumes

and;
http://forums.rennlist.com/rennforums/showthread.php?t=267119&highlight=exhaust+fumes

and;
http://forums.rennlist.com/rennforums/showthread.php?t=266133&highlight=exhaust+fumes

also, find a better mechanic who knows about porsches, not just any joe-blow redneck wrench.

[KevinC]

I too have this exhaust fumes problem ('87 951) and can't determine source. I have had hatch latches adjusted to ensure a "proper" seal. Seems tight. I know I have a poor sunroof seal (this might be why I get wet when I wash the car in the no-touch!?!) Anyway, the fumes enter the car immediately on start up. There is no fuel smell, no anti-freeze smell. Not rotten eggs either. Just a dirty, stinky, almost noxious scent that gives me a light headed, foggy feeling. Probably dangerous too! If the windows are closed and I am at speed it seems to dissipate somewhat. But it's pretty bad even when standing at idle, so I don't think it's any of the glass or door seals, but possibly a leak in engine compartment or under the car?!?! Thoughts?

[Techno Duck]

Check condition of the rubber seal on the firewall and around the shift boot. There should be an inner rubber boot that cracks with age/heat.

[Gawernator]

Also check your hatch seal which can let in fumes, a cheaper replacement is at only944.com

GL

I also just realized if your OEM rubber inner boot is FUBAR, Kyle at the above website came out with a $20 leather inner boot.