BK67STANG

Hi,
I am new on here. I'm inquiring for my 17 yr old son actually. He has a 67 Mustang that he and his father built from the ground up. He's been having horrible exhaust fumes coming through the vents that are so bad, my eyes burn. Everything I've researched on it we've checked. My son said the vent "system" is not hooked up yet, so the vents are open. Could this be the cause? He has a new exhaust system, no cracks or leaks. It was double checked to makes sure it was hooked up right, so there weren't any leaks. I feel so bad for him, as he bought the car with his life savings from a woman in Texas who lied completely. When he got his car, it was junk. My husband has knowledge about cars, but he isn't a professional and doesn't know it all. We have a 91' mustang, but that has never needed the major work my son's car needs. If anyone could offer us any input, I'd truly appreciate it.

andrewmp6

If exhaust is coming in the car from the dash vents you have a exhaust leak under the hood.If he put headers on it did he re torque them after 2 weeks?

BK67STANG

Andrew,
He said he didn't put headers on.
I really appreciate your reply. Thank you

1971mach1

It could also be the PCV not working properly. Nasty crankcase gasses can smell like exhaust. The PCV system sucks those back with intake vacuum to be reburned. Clean air gets sucked into the breather so if it's clogged the the PCV can't extract the bad gasses.

The gasket under the hood near the cowl may also need replacing or there's a hole in the firewall somewhere.

2+2GT

If there are no leaks in the exhaust system, then even a hole in the firewall would be unlikely to do as you describe. With an intact exhaust system, the only way fumes can enter the passenger compartment is through poor or missing seals in the rear. Taillight housing seals, rear bumper seals, trunk lid seal, trunk floor plugs, quarter panel drains, sealant between gas tank and trunk floor, backup light wire grommets, are just a few of the paths for fumes to enter the car. One other thing- fumes that strong also suggest poor carburetor tuning.

This is a great project, well worth pursuing. With all that work in the car, your son is unlikely to do something stupid in the car.

BK67STANG

They think maybe it's the carburetor (since they have yet to rebuild that). Now they are going to work on getting that rebuilt. Thank you 2+2GT! Actually.. thanks to all for taking the time to respond! We really appreciate it!

2+2GT

You still have a problem.

I don't care if the carb is so bad the car is belching green smoke, no fumes whatsoever should be getting into the car. Until you solve where these fumes are getting in, you will be at risk from CO emissions.