I often drive my '63 wagon with the fresh air vent doors wide open. I like the ventilation. However, driving around on the freeways here in LA, I noticed just yesterday that any time I brake, I tend to get a noseful of gas fumes. At first I thought it was external exhaust from other cars: now I think it's my own exhaust I'm smelling.

Is this caused by my fresh air vents?

Second comment is that I also tend to like to roll the back window of the wagon down partially when driving and leave the other windows up (with the fresh air vents open). I can't tell yet, but it seems particularly bad when I do this. Does keeping the rear wagon window open while driving actually suck air into the cabin?

Final comment is that yes, I do have two small holes in the firewall of the front passenger compartment where the A/C hoses routed through. I haven't plugged them yet. But before everyone jumps and tells me that this is definitely the problem, a side note to say that I've always noticed this smell (now that I think about it) even when there were hoses routed through the firewall. Maybe very slightly less, but the fumes were still there.

Here is what is happening. When under way a low pressure area develops at the rear of a trunk of a sedan and station wagon as well as low pressure in car’s interior as air flow around the body. Opening the tailgate window allows faster transfer of exhaust fumes into interior and low pressure inside helps to suck in fumes from engine compartment.

Installing new fresh soft sealing gaskets at all doors & tailgate, and trunk if one has a sedan will greatly reduce fumes and pressure differentials inside of passenger compartment. Don’t forget to renew all the tail light gaskets as well, and while you have them out clean the inside of the housing and lenses for brighter running & brake lights. Detroit Muscle has almost all the lighting gaskets for A Bodies

About the only way to get around the fume problem is to roll up the windows, close tailgate window, open the foot well vents, and turn heater fan to full speed to increase interior air pressure.

I have had the same problem with my rag top when its top was up… go figure a drafty rag top. New gaskets at trunk, and tail lights helped a lot. You will be surprised how dry degraded leaking gaskets around the lights can flow so such a volume of toxic fumes into the car, I was.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC