I drive the '69 and my lady drives the '67. Lately we've been experiencing severe headaches, fatigue, dizziness and just plain feel lousy, I'm betting, due to fumes coming into the interior. It doesn't smell like gas or anything like that, but every time we drive, we suffer from those symptoms I mentioned. I suspect that carbon monoxide is somehow present.

The '67 has a good interior with all panels, weatherstripping, etc. in good working condition. The firewall is sealed as best as it could be with no noticeable holes. The trunk weatherstripping is nearly new. The floor pan has no holes except where the floorshifter is hooked up. The engine has a little bit of oil on it from the slightly leaking valve covers, but there's no smoke or foul scent. The fuel mixture is probably a little rich. One thing I notice that seems fishy to me is this -the heater air duct under the dash in the center of the car is constantly pushing out hot/warm air. It doesn't matter how I arrange the heater/defroster/etc. levers, warm air is constantly coming out of the duct. Is this normal? I can feel it on my face as I drive or sit in the passenger seat. It makes my eyes burn and I'm sure is contributing to the headaches and woes. If this isn't normal, what could cause this sort of problem and what can I do to fix it?

The '69 has a bunch of other possibilities. So far I've replaced the trunk weatherstripping and covered up holes in the firewall. The floorpan has no holes. My interior has no headliner, is missing one door panel, and has nothing above the back seat to cover the opening to the trunk. The valve covers are leaking enough to drip some oil onto the headers. The hood is a cowl induction glass hood, but it's arched and bent from heat and leaves a large opening between the fenders and hood. I'm thinking some of those burnt oil fumes could be coming into the windows directly from the engine bay. My fuel mixture is on the rich side because it runs like crap if I go any leaner. My heater assembly is long gone so I don't have the problem I have with the '67. What other ideas do you guys have and what areas do you think I should attack first? I don't have much time or money so I want to make sure I don't fiddle around too much.

This has been such a problem that we're almost considering putting our Chevelle dreams on hold and selling our beloved rides. It's the last thing I want to do, but I literally feel like I'm dying from carbon monoxide poisoning. I haven't given up yet though. Any help would be GREATLY appreciated.

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John 69MalibuChevelle

throw a couple of those CO detector buttons in the cars and see if they change color,
you can pick them up in the hardware store.
Also check the exaust from the headers or manifolds all the way to the end of the tail pipes for leaks.

You do have a serious problem. Without more info you may try looking at things which both cars have in common and/or modifications to both cars which are unique to your personal preferences.
Both cars share a similar design of the heater ducting in that the fresh air is drawn in from the cowl area at the base of the windshield. Even when the heater controls are in the 'closed' position, there is no absolute seal from the outside environment or the engine compartment vapors, if there are any.
Any engine running at any throttle opening from idle to wide-open can easily emit a lot of fuel vapor depending on the air cleaner housing design, PCV system, carburetor calibration, etc. A 'raw fuel' vapor standoff (cloud of fuel vapor above the carburetor) is commonly associated with long duration cams that sound pretty cool but don't operate very efficiently at low-rpm, part-throttle situations.
Look carefully at the cowl plenum area and any possibility that engine bay vapors may be entering the fresh air ducting of the heater system.
I live directly east of you by about fifty miles so the better your car runs, the better you'll be and the cleaner the air will be by the time the afternoon breeze pushes it through this end of the valley.

Good luck,

Louie

My 68 SS has that same problem as well. I was thinking the heater box needs new seals or exhaust leak coming up through the floor shifter hole. Mine also has a little leak coming from the valve covers and that bit of oil does get on the headers and smokes alittle. That may be the problem as well seeing we both have similiar situations.

Take a piece of paper, cut it into about a 2" width. Open your trunk, and close the trunk on the paper. If you can pull the paper out easily, your trunk seal isn't sealing as it should. Try this in several areas, but pay special attention to the rear part of the trunk.
In addition, if your exhaust dumps ahead of the rear axle, it will magnify the exhaust billowing and entering the cab area through the trunk.

On the 69 I agree about the trunk. Remember it had astro ventilation and so it pulls air all around the car including the trunk if not sealed right which means pulling the exhaust right out of the tail pipe.

I don't have a exacting answer for you on this, but I do know of a phenom that happens with certain cars (my 57 was bad at this) when the cars rear end is jacked up a little, and the exhaust tips are straight out the back which means they are right in the low pressure area of the rear of the car that is created by movement of the car down the road and actually produces this low pressure void or vacuum area of sorts behind and under the car right up to the engine compartment! How many times do you look at the back of your car only to see lots of dust on the rear bumper! Caused by this very effect.

The exhaust can get expelled right into this vacuum area and travel from back to front and up the firewall out the hood crevaces to the fresh air vents and even curl around into a side vent! I actually had this happening to my 57 at the side window vents (since my 57 has fresh air from the front over the headlights instead of at the cowl) when I opened them only to be hit in the face with exhaust fumes. It took me some research to figure this out and was crazy pluggin holes. One thing that could be happening is that it can travel thru your trunk seal (if the seal is not tight) and inside the trunk up thru the back plenum to the interior. The interior is always at a lower pressure than the outside of the car even with the windows down. You migh try to put plastic behind the back seat and seal up that area profusely. This worked on one buddies of mine GTO.

I don't have an exacting remedy only to say that this is one of the reasons that some cars have side exit exhausts and/or tailpipe ends that create turbulance exiting the rear (such as the 70 olds 442s) to help with this issue.

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Steve "Jack'stands" Jack
Tech forum at Jack'Stands Cooling Forum (http://www.inccn.net/techforum.htm)

Make sure the cowl seals across the top of the cowl are present and doing their job. The hood on the '69 also has a seal. With that many fumes I would also be checking out the carb as well.

.

[This message has been edited by supersport396_2000 (edited 02-21-2003).]

I really appreciate the feedback guys, good stuff. If you think of anything else anytime soon, let me know. I'm definitely not giving up yet, especially when there's so much info and help on TC.

Old longboarder-
I did that little paper test and it seems the seal could be tightened up a bit. Thanks for the tip!

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John 69MalibuChevelle