Gumby

notchback and strights out the back

Anyone else ever have a problem with fumes getting inside?

Ive sealed up everything, all I can rule it down to the low pressure zone of the notchback is the problem. [all new seals, gutted rear section to check for holes or leaks, tight as a drum]

pipes come out dead center, and stick out past the bumper a few inches.

Soon as you crack a window, its fume city.

I think I discovered this as this past week or so it was not doing it, I then found a 2in hole in the pipe near the R/R tire. I fixed that hole today and its fume city with a window crack again.

Totally blows, I like the dual tips out the back center, nice euro look with the notchback.

Gumby

And I was right, sure would like a wind tunnel to find out more though

See how exhaust trapped in the low zone ends up coming in the window when cracked.

had to have both all the way down or up most of the summer, or fume city.

chopped it off by the door and use a turn out, that sticks out nearly as wide as the tire and angles down, to get the exhaust out and away from the car, no chance to get caught up.

allot louder inside though, next year Im going to rebuild it and do the same but have it exit on the other side of the tire. Just don't feel like doing it, as my system is all welded.

Gumby

WOW IS IT LOUD WITH THE EXHAUST COMING OUT THE SIDE, CAN ANYONE HEAR ME?

InfernalVortex

iTrader: (4)

Are you sure you dont have some sort of leak near the y-pipe under the car?

Gumby

Well moving the exhaust tip to shoot out the side fixes the fumes problem, but its awful loud, but it is in front of the rear tire. in the next two days IM going to rebuild it again, trying to still shoot out the side but as far back as I can.

85Z28NOS

iTrader: (2)

I never noticed any fumes with my notchback on my car. I recently removed it for some mods and re-installed the factory glass. While the glass hatch was off I replaced the three piece spoiler with a 91-92 high rise. I had drilled the new holes to mount it on but hadnt welded up the old holes before I mounted it on my car. I have noticed some fumes coming in threw those small holes but dont drive it everyday right now and dont intend to leave it on the car much longer. My wife liked the factory notchback more, says it makes the car more unique.

Gumby

Its gotta be something small and hidden, ive had the whole rear section apart, tail lights, caluking, under coat sealing, every seem, hole, wire grommet.........

Ive gone above and beyond on that part but it never fixed it 100%

in the summer it was ok, just put both down and its fine, but with colder temps, sometimes you just need to crack one window.

If I had more time and fab skills, id build a rear bulk head, so when the hatch is shut, the rear section is now sealed off from the cabin.

Another spot I was going to look at was the license plate light bumper cut out, since both it and the exhaust were in the center and close. was going to heat up a square of clear plastic and mold a cover and seal it in place.

InfernalVortex

iTrader: (4)

how is your transmission/shifter boot? The one under the console?

Gumby

That was also one of those thing that got a level 3 bio hazard sealing

InfernalVortex

iTrader: (4)

This is while you're moving or while you're sitting still?

Maybe you have a fuel pump hatch you may or may not know about?

Gumby

Oh I know about the FP hatch its well sealed.
best mod ever

yea its only a moving problem

Gumby

well dumping in front of the rear tire worked but was to LOUD, I move it as back as a I dare and have it stick out as far as I can deal with looks wise and angled down, to make sure the exhaust gasses shoot out past the air streme around the car.

TreeFiddy

Why not just point the tip(s) out the back as usual - you're just about there anyway.

Gumby

read the thread, straight out the back I get fuemed out when a window is cracked, trying to keep it on the side but a far back as I can for sound. Id leave it dump in front of the R/R tire if I wouldn't go deaf.

tired of fumes, with it on the side, no fumes come in.

WickedCrazy

Have you checked your spare tire area? I had a bird that had an exhaust issue like you are describing and it ended up being a hole in that lil area that sucked in fumes really nicely.

InfernalVortex

iTrader: (4)

I find this whole thing exceedingly odd and interesting.

If you have fumes from under the bumper flowing back around the top of the car enough to get into your side windows at speed... you must have some REALLY odd things going on aerodynamically. You'd have to have a massive pressure differential from the hatch area compared to the area under the bumper cover. I wonder if you had ground fx if that would help...

TreeFiddy

Agreed, it doesn't sound like exhaust from the back is really likely to rear up and travel forward half the car's length to enter the windows. Does sticking out the side like that actually stop it?? My money would be a header or y leak. Had a tiny pinhole in my y once that gassed me out, also only with the windows open.

sailtexas186548

iTrader: (2)

seafoam it and drive, you'll find out where its coming from

Gumby

IVe been fighting this for a long while, can't seem to find any more leaks in the rear to cause that, and just tired of fumes.

so im doing what works, giving up some looks, as it looked nice with dual tips center of the rear with the notch.

and id like to see the car in a wind tunnel, soon as I put it on, I noticed birds no longer skipped off like a forcefield, they would get sucked into the hood more and you see them give much more effort to escape, before the notch I could hammer down and they escape fine, with the notch, ive braked before one went up the hood scoop.

making me think I got faster airflow, which could make an awful pressure bubble in the rear in the notch area, right where the exhaust exits, making a hidden pin hole like a 4in pipe when the window is open just a bit a gas out.

I have delousions of making the notch window flip out at the bottom like a cheap flip up sun roof, or into a slider like a pickup but the fumes would kill me.

InfernalVortex

iTrader: (4)

Maybe try the seafoam thing then. See if you notice anything weird under the car. Worth a try at least, but its hard to pour seafoam down the throttle body when its going down the road, so it probably wont be all that conclusive.

Gumby

Yep and

It just hit me, maybe thats how Batman does his smoke screens, seafoam injection

Gumby

Got a decent drive in today, all I smelled was burning paint, no exhaust fumes, which I expected, I painted the whole thing from Y pipe to tip.

Gumby

Found the problem by accident, 13 some years ago I gutted the whole car and fix all the floor rust, well at some point places that didn't need fixed now need it. Found a hole right near the rear seat belt buckle in the floor, noticed it when something splashed on the exhaust and I saw smoke coming out the seat belt slot in the r-rear plastic.

Just some spray foam for now to seal it, guess it time to gut it again... darn salt belt