Exhaust smell inside vehicle

[Purple Mach One]

Hey guys. I've got a 69 Mach One with a problem that exhaust fumes are getting inside the car. About two months ago, I drove for a short time and I started to smell exhaust fumes come inside the car with the windows down and developed a headache. Is it normal for these cars to have exhaust gases go inside the cab with the windows down? I would think this poses a serious health risk. Also, the underneath of the car is covered with undercoating. Do you think the undercoating is also contributing to the bad smell? Please anybody let me, I want to get to the root of this problem. Thanks

[bnickel]

i have found that most often the exhaust smell inside the car is from holes in the floorboard, firewall etc. and driving with the windows down causes the exhaust to actually get sucked in from under the car. at least that's how it was with my car anyway

[bswor]

Yeh i had/have a similar experience because i had rust holes in the drivers floor pan. Finally got that fixed but there is still a hole in my firewall which isnt fixed yet and i still get that smell sometimes.

[Pakrat]

I actually kinda like it...............man. 8)

[bswor]

Yeh i kept wondering why my eyes were red and i felt wierd after driving lol.

[fastback40]

SO you think its exhaust fumes instead of fuel? I'm having the same problem and dont know which it is. I have a everything new from the tank to the carb. Can't tell if theres any leaks, but I'm getting the smell under load. Its fine when it idles.

[bswor]

I also had the wrong type hose going from the fuel filler neck to the tank. So i was getting a gas smell in the car.

[fastback40]

Well I just checked that and everything looks dry and dusty. I bought the hose from Dallas Mustang so I'd assume it was the proper one. What hose did you buy that was wrong? I didn't think a radiator hose would fit. I was hoping the smell would go away but it hasen't. Just strange that I only notice it on load.

[DragPack69]

I also had that problem pretty bad.
I re-aligned my hood so the rear seal at the cowl was a little tighter, checked ( replaced) the steering column seal, and retightened all of my exhaust manifold bolts along with the clamps on the exhaust.
Seems to be fixed so far, we`ll see when spring gets here.

John

[fastback40]

Dragpak I was kinda thinking that it might be a firewall seal issue as well. The car was in the paint shop for 2 years and I wondered if it might be an exaust issue. I just don't remember ever smelling any fumes from an exaust leak. I just remember hearing an exaust leak! Heck I don't even know what an exaust leak smells like. I had a msd plug wire that keeps poping off one of the spark plug. Any chance the fuel smell could be coming from a enriched carb or a sparkplug not firing?

[DragPack69]

Absolutely, thats raw unburnt fuel passing the exhaust valve and it has no where to go but out and it will smell.
If you can "hear" an exhaust leak, it can get drawn in to the car by a very small tear in your firewall seal or a small hole on the floor if your windows are down.
I`ve heard that this problem is common in cars with the fold down seat.
(I have this option.)
There really isn`t a seal between the trunk and the cockpit.
Hence the drawing in of fumes.
Another place you may want to look is the seal between the firewall and the heater box.

Hope this helps,

John

[fastback40]

Gottcha I check it out. Thanks!

[Purple Mach One]

Absolutely, thats raw unburnt fuel passing the exhaust valve and it has no where to go but out and it will smell.
If you can "hear" an exhaust leak, it can get drawn in to the car by a very small tear in your firewall seal or a small hole on the floor if your windows are down.
I`ve heard that this problem is common in cars with the fold down seat.
(I have this option.)
There really isn`t a seal between the trunk and the pit.
Hence the drawing in of fumes.
Another place you may want to look is the seal between the firewall and the heater box.

Hope this helps,

John


Hey Dragpack69, I've got a 69 Mach One with the fold down seat option. What have you done to correct that problem?

[DragPack69]

I`ll start from the front:
First I re-aligned the hood and made sure it was down enough to seal, replaced the column seal, tightened every nut on the exhaust system including the manifolds,resealed the plugs in the floor, re aligned the doors and windows, checked the heater box, and took out the gas tank and re-sealed it to the trunk floor.
Another thing you can check is your timing, if your off a little, your combustion chambers won`t be burning all of the fuel.
Of all the things I mentioned something fixed the problem about 85%
I still have a little, but my timing is very touchy, so when the weather gets better I`m going to tweak it a little.
Hope that helps,

John