1966 Barracuda - exhaust smell

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robodhran

robodhran

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When driving the Barracuda, my wife complains, that there is a smell of exhaust air (not fuel) inside the car.

I do not bother that much, but she's right; it's even stronger when windows are openend. I already changed the trunk rubber seal to make that trunk compartment tight, with positive but little effect.

There is no exhaust escaping from the engine compartment; only from the exhaust pipe.

Anyone has the same "issue" or has someone a clue, what might be causing that smell (scent) to enter the car?

Robert
 
Where does your exhaust exit? Out the back or does it dump under the car somewhere? Is it while you are driving, or sitting that you smell it the most?

The only time I have heard of that is on old Suburbans, trucks with top caps, or station wagons, when you drive with the back window down. The "vacuum bubble" right behind the vehicle can suck the exhaust back into the vehicle. Is your Barracuda a fastback or hardtop? Is it possible you are missing some plugs in the trunk floor that are allowing the exhaust to come back in while you drive.

Strange that you smell it more when the windows are open. I would have thought that would bring in enough fresh air and kind of flush it out. You're sure your exhaust flanges aren't leaking under the hood?
 
Put a glove on and block the tailpipe.while its running of course.
If theres a leak you should hear it.I hope my 65 isnt like that. Thats one thing my body cant tolerate any more.
Hope you figure it out.
 
same with mine (and my wife) - trunk seal - OK; drain plugs - OK; vents covers at top of trunk opening - catching on lip of trunk opening - not OK : put a strip of foam weather seal across the bottoms so they wouldn't ride up over lip; wife hasn't ridden in a carbureted car for 30+ years - not OK, problem cannot be resolved.
:D
 
This is the car. The plugs should be ok too. I put in a new set of carpet and checked them all.
I'll check the lips (on 2nd pic). Maybe they are not fully airtight. A good spot to suck in air or exhaust gas from the outside. You can see the exaust pipes pointing away from the car. Nevertheless I'll do the glove-check as well. Thanks for your helpful advices.

WP_20170219_15_00_04_Pro.jpg
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I see the tailpipes do turn down so that should have helped a lot. As outside air enters the cabin through the vents/windows, it exits through those flaps (AKA fresh air ventilation). They are designed to be able to lift up a little as cabin air flows out. Hope you can solve the problem Robert; that exhaust smell is nasty!
 
I have a 65 and 66 Barracuda, both Formula S cars. I believe the rear end aerodynamics of the early Barracudas are such that the design creates a vacuum sucking exhaust gases onto the lower edge of the trunk lid and even onto the top of the driver side tail light. On any early non restored Formula S cars, look at the driver side bumper chrome and tail light chrome and you can see the caustic effects of exhaust gas. For this reason, I frequently clean these areas on both of my cars out of necessity....the 66 is white and the 65 is silver.

The trunk seal is the most important item in the mix. If it's leaking there will be exhaust gas smell in the cockpit. And as stated in posts, the flow through ventilation flaps must also seal.

One thing not mentioned so far is a possible leak under the upper chrome trunk strips and hinges. (Where the fish or Valiant medallion is located). The hinges and chrome strip came from the factory with foam gaskets to seal them. Check to see if they are present.

I wonder if the 2 barrel 273 with its single downturn tail pipe has the same problem with exhaust gas. My 66 and 67 Chargers have downturn tailpipes exiting a couple of inches forward of the bumper and I see no signs of paint discoloration or exhaust smell.

It would be cool to see wind tunnel tests to determine the air rear flow pattern of these cars. Perhaps a properly positioned deflector would solve the problem.
 
Are there any rust holes in the trunk?? The most common areas to look for would be right around where the trunk pan meets the wheel well, down inside the trunk drops, or along the rear pan where it meets the tailpanel! Also, look at the taillight bezel gaskets, to see if they're cracked or missing pieces!

I had a 66 that I sold that had a couple small areas of rust through in the trunk around the wheel well, and it did the exact same scenario as you have, especially when the windows were down!
 
pbiggs said:
I have a 65 and 66 Barracuda, both Formula S cars. I believe the rear end aerodynamics of the early Barracudas are such that the design creates a vacuum sucking exhaust gases onto the lower edge of the trunk lid and even onto the top of the driver side tail light. On any early non restored Formula S cars, look at the driver side bumper chrome and tail light chrome and you can see the caustic effects of exhaust gas. For this reason, I frequently clean these areas on both of my cars out of necessity....the 66 is white and the 65 is silver.

The trunk seal is the most important item in the mix. If it's leaking there will be exhaust gas smell in the cockpit. And as stated in posts, the flow through ventilation flaps must also seal.

One thing not mentioned so far is a possible leak under the upper chrome trunk strips and hinges. (Where the fish or Valiant medallion is located). The hinges and chrome strip came from the factory with foam gaskets to seal them. Check to see if they are present.

I wonder if the 2 barrel 273 with its single downturn tail pipe has the same problem with exhaust gas. My 66 and 67 Chargers have downturn tailpipes exiting a couple of inches forward of the bumper and I see no signs of paint discoloration or exhaust smell.

It would be cool to see wind tunnel tests to determine the air rear flow pattern of these cars. Perhaps a properly positioned deflector would solve the problem.
Click to expand...

Found a rear end picture of my 66 prior to restoration showing the exhaust effect. Notice the driver side paint discoloration and bumper chrome. Back-up lense is exhaust clouded and chrome pitted.

66 Barracuda rear view.jpg
 
Surely there are no rust holes anymore (at least I hope so...). But all different areas have to be checked; especially the two ventilation flaps and the upper chrome trunk strips and hinges. It's a four barrel commando engine, but not a formula s. I found a video-clip from 2014, when I brought the car home. Very impressive to see that soot on the trunk lid on both sides where the tailpipe is located.
Notice the bang at the end of the clip....that's when I hit my head on the roof.... 8 ))

 
Robert
What are the chances the "scent" is coming in thru the cowl, where the fresh air is directed to the interior of the car? There are many entry points,both above, and below, the hood.
One of the easiest I have seen is around the heater core pipes, or even the heater blower motor. Or the worst is a rotten plenum.
There are many others; like a missing cowl seal.
A missing seal at the core-support will pressurize the underhood area, increasing with speed.
Of course that scent would be created by leaking manifolds/headers. Or a faulty PCV system. Etc.
 
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I had the same issue with my 66 Dart. The speedometer cable grommet was shot and the lower steering column seal was cracked worse than the speedo grommet.
 
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