abolfaz

I've had my 88.5 turbo S since it was just over a year old, I've driven the hell out of it and have a small fortune invested in maintaining the car. About 6 years ago the exhaust gas smell got so bad in the car it became nearly impossible to drive. I left the car with my mechanic who put in new hatch seals etc and was unable to make the smell go away. I cleaned the car up and put it in storage.

Missing the car, I went over and got it going again over the weekend and took it for a spin. In less than 20 minutes the smell got so bad that I had to pull over. I've gone over all the regular checks (hatch seal, plugs in trunk area, etc) and can't find the source of the leak. Anyone ever come up with a solution for this? I can't tell you how much I love my Turbo, but this smell has made the car unusable.

Any ideas? Also, any 944 Turbo experts in the Miami/south florida area?

Dougs951

Hmm shot in the dark here but, do you have the rubber shifter boot in place? That coupled with an exhaust leak could cause the smell.

eyeball kid

You mentioned hatch rubber, but are you sure that the pins are adjusted correctly. If they are letting the hatch ride too high the rubber may not make contact, and you can get leakage--well that's what was happening to mine.

CPR

A,
Perhaps the BIGGEST overlooked area in regards to exhaust fumes is the rear-tail light assembly seals.

Maybe it is because these have just started to fail ( although on 86's I see it often when doing the clear tailight swap). There is a significant vacuum that is created predominantly on the driver side assembly (due its relation with the exhaust), but it has also been present on the passenger side assembly as well.

A tell tale sign of seal failure is the " black streaking " that occurs underneath the tailights and down onto the bumper. This is your seal failing.

BTW...I use the term "seal" loosely as there is no specific gasket, but a pliable butyl stripping that is applied around the lens.

abolfaz

I forgot to mention, before I stopped driving the car I had my mechanic reseal the hatch, change the hatch gaskets, hatch lock seal, etc. Sounds like the tail lights could be the culprit.

JohnKoaWood

You can also take the car in an have them fog check the exhaust for leaks... could be a post turbo leak blowing exhaust near the firewall / floor pan.

951Ron

Had a similar problem. Turns out it was exhaust header tube closest to the firewall. The original owner of the car had replaced the catalytic converter with a nice aftermarket unit but forgot to replace the exhaust hangers and rubber "doughnuts" that support the weight of the cat. So the exhaust tube closest to the firewall was actually moving in and out from the mounting flange at the head. Not good!

Sounds like you maintain your car much better than that but it might be worth a check.

Here's a long shot - the motor mount on the exhaust side usually goes bad first.
When was the last time you checked them or replaced them?

minho78

Agree.
I think the fumes are comming from the front of the engine. It could actually be from a craked header or cross over pipe.

Trucho-951

Last year, my car developed another exhaust smell, looked it over, this time, it turned out to be a tiny oil leak from the rear cam cover gasket. All it takes is for a small oil seep, once the oil touches the hot exhaust header, viola, enough exhaust fumes to make one not want to drive the car anylonger. Just food for thought.

Matt Sheppard

The main reason you will smell engine fumes is if you have any breach in the firewall-to-hood seal. That seal is cheap and covers a multitude of sins.

JC951

I recently just put a stock cat back onto my car because the one that was on it was gutted as well as putting the exhaust that came on the car when i bought it back on for emissions testing. When I first got the car in 07' I could smell exhaust fumes and it would stink up the car. I had bought a broadfoot racing exhaust (which I love...wink wink...nod nod to Albert) The exhaust fumes started to go away for the most part when I changed the exhaust. Now that I put the stockers back on i'm getting the smell again. The donut o ring between cat and catback is toast which could be part of the culprit for you. Also there was a small exhaust leak coming from the downpipe to cat, though very small, I think most of the smell had to do with the leak coming from the cat to catback donut.

toddk911

My fav tool for finding exhaust or cabin leaks is the leaf blower.

For exhaust leaks just put the leaf blower up the tail pipe and get it to seal and stay locked in place and then you can go tothe engine bay and check the headers, etc.

For the cabin just have someone run the leaf blower over the seals with someone on the inside and can find them easy.

O go to a touchless car wash that has high power jet sprayers and will see where water leaks in in the hatch area or under the dashboard, etc.

aj986s

Are you smelling exhaust OR gas fumes?

If gas fumes, a possible problem is that the vent line from the gas tank may be crushed under the car. Its a hard plastic tube, that feeds into the charcoal canister (under the LF fender IIRC). On my 944Cup racer, the canister is gone, but the tubing feeds into a small filter in the engine bay. The purpose is to relieve pressure in the tank, due to the backfeed from the fuel injection rail to maintain constant fuel pressure; excess fuel is routed back to the tank. As fuel returns, the pressure is vented off into the intake via the charcoal canister. If the hard tubing under the car is crushed (due to rock, etc.) then the tank can't vent.

Biggest clue is excess pressure escaping when removing the gas cap. Also got worse with less fuel/more air space in the tank. I believe the excess pressure was forcing fumes out the seals of the fuel inlet pipe or the tank sending unit cover. The gas fumes in the car had gotten so bad my eyes would burn. I cut out the crushed section and sleeved some vinyl tubing over the two good ends, and tied off with a couple of small zipties. The fumes and excess fuel cap pressure immediately went away. On my '84 NA car, the vent tubing runs under the driver's seat. Look for the tube that goes up to the top of the fuel tank.

Oddjob

Yes, check this seal first. Any fumes from the engine bay will be pulled into the cabin by the HVAC blower.

DivineE

+1 on this theory. Since you've covered my first guess of the boot (tail gate) seal I'd go for a crack in the manifold. Fumes come stright in from the engine bay and cracks do happen with turbo's