Peter 642

I've been getting a faint "gas" odor when running the car on longer trips, and thanks to the posts here, I realized it's probably a bad hatch. I'm replacing my trunk hatch bolts, but in the meanwhile, I noticed that there's a gap in the seal around the trunk. Is that supposed to be there? First pic is right above the trunk lock, looking into the car. Second pic is with trunk open.

I took a look at the trunk lock; it looks intact, but...well, odd. What's that hatch doing, off-center and apparently broken off (third pic)?

Thanks.

mclarenno9

Funny, I was just looking at this same "feature" on my car not too long ago while doing some work. I had always heard of the whole hatch seal issue causing some exhaust gas to be sucked into the car, and never thought much of it until I saw that huge gap and what looked to be a dirty area on the underside of the hatch there. Since the area directly behind the car is generally one of high pressure, it makes sense that the exhaust would find its way through that gap. This is also why the backs of cars always seem to be the dirtiest.

Anyway, I put a piece of foam in there, held in place with some clear silicone. It has seemed to really cut down on the gas smell in the cabin. Now I don't smell like I just cut my grass after a short drive...

JohnKoaWood

We can fix this, we have the technology, we have the ability....

I found aftermarket seal that works great, is a direct replacement for the factory part... but I had to buy it in bulk (200 ft IIRC, but I really have forgotten)

I have so far only used 4 cars worth of it.. (15.5 feet per car BTW)... but I DO need to put some on My N/A..

Peter 642

Heh. Are you selling it in 16 feet segments? Or better yet, 1.5 inches?

JohnKoaWood

it is continuous feet... if you ONLY want 2" (that is what I told her anyway) I can cut it off and send it..

PM me your address... I'll have it off to you tomorrow...

F18Rep

You may be able to pull it loose for a few feet and reseat/stretch it to close the gap - I've had good luck doing this. Also I found a small plastic dowl rod (maybe 5/16ths dia) and used it to fit into the hole formed in the seal. This helps to join the ends. (not sure where I got that idea, maybe it came that way from the factory).... Bruce

ideola

Any failure to completely seal at the hatch WILL result in fumes being sucked into the car. The entire chassis is setup to "breath" (note the door vents and the vents under the carpeting in the sides of the sheet metal in the hatch area), so there will be negative pressure in the cabin as compared with the rear hatch area. The natural turbulence back there will cause fumes to be sucked in through any small opening. That's a pretty large one!

This is a problem that plagues ALL of these cars from the earliest 924. At some point, Porsche introduced an "additional hatch gasket" (944.512.463.00) that attaches to the underside of the hatch were the spoiler screws are located. I've noticed this seal on 1987-onward 924S, and also on a 1985 944 that I parted, but I don't know when it first appeared. When I fitted the '85 944 hatch to my '81 924, I noticed that the fumes were completely eliminated. Even with new hatch seal and properly adjusted hatch height (using the sheet of paper trick), the car still got fumes, but the 944 hatch with the add'l gasket seemed to eliminate the problem entirely.

Also check around the taillights, and where the license plate frame attaches, make sure ANY gap is completely sealed. The angle and position of the tail pipe makes a difference too. If the tail pipe doesn't extend far enough, more fumes get sucked into the car, and I believe some can even make it in through the drain holes if the tail pipe doesn't extend to stock length. I've read reports by others that putting a turn-down on the tail pipe helps too.

The one I haven't been able to solve is fumes coming in through the driver and passenger windows when they're barely cracked and the sunroof is closed.

alordofchaos

At home DIY stores, they sell foam "caulk backer" in various sizes that should work well for this.

It's the gray stuff meant to fill in really large gaps before caulking. Pretty cheap, and flexible. If it's too big, you can just wet it up and squeeze it in

(Yeah, that's what she said)

JohnKoaWood

Vapor canister and vapor purge system on / in the left side fender... I bet it ONLY happens when you fuel tank is at or near full, but not when the tank is below 3/4 full... if fuel makes its way to this area, or the canister is cracked it will off gas the fuel vapors into the passenger compartment due to the wind buffeting on the mirrors (much the same way you get rain comin in if you just crack the windows when it is raining...)

ideola

Nope. Happens all the time, on all of my cars. Window partway down, sunroof closed, instant exhaust fumes (not to be confused with raw fuel vapor).

ZR8ED

The side windows being down is not nessessarily where it is getting sucked in. It is just making the negative pressure in your cabin even worse. It is most likely still coming in from the same placeses it does when the windows are up. With the windows down, even the tinniest of holes can seem like direct links to the exhaust pipe!

Just to clarify a previous post, the air pressure behind the car is negative. The low pressure area behind the car can draw in/trap exhaust gases from getting out and away from the car.

Extending the exhaust pipe or turning it slightly down will make an improvement, if you can't/won't solve the cabin air leaks.

BTW my seal has that same gap. Another DIY weekend project.
Scott.

Peter 642

John, thanks. I'll try the grey DIY stuff before I make you go through the trouble.

Why on earth would this be the design/design flaw?

jmmullner

Wow, I just noticed the same thing although mine is a bit wider. I always forget about it when I'm washing the car and water sprays into the cabin. John, could I get that 2''?

JohnKoaWood

If you want, I have... just shoot me a PM, or E-mail me at johnkoawood@aol.com...

Factory replacement is $120ish.... a full car seal of mine (16ft, virtually identical to the factory seal) is about 1/4 the cost... play nice in the sandbox as I know at least 2 cars running arround with this as last years christmas gifts...

WizPorsche944

Mine seal is the same way, the p/o put a small piece of hose between the ends of the seal.

I cannot figure out why the factory would leave that gap in the seal.