Guys, I certainly appreciate your involvment in getting this issue fixed. Today we had excellent weather and I had to drive with the tops on as I had my daughter with me. I also quit smoking 42 days ago. I would hate to die of Carbon Monoxide poisoning from the Corvette now that I managed to keep it up without the cigarettes (at least with the corvette, it would have been worth it) How dumb of a story would that be?

I had her running today and took a breath underneath the car. No fumes whatsover, so that kind of deletes my suspiscion that there are any holes in the pipes, unless of course the fumes would go directly upwards (which they do, but I kind of doubt the hole theory now). There was really NOTHING.

I now really wonder if the cabin pressure is keeping the fumes from entering through the aqua vent piping. I guess I could seal these for a test drive? then I would know for sure if it is coming from there. I guess it is eliminating options here one by one. Such a nice ride and such an annoying issue!

Oh, as to the Autobahn: way to full these days.....you would have to find one that leads to nowhere to have some fun. In any case, I would never drive faster than 120kmh with the vette....you never know

thanks again for all your input guys!
omar

 

Good luck figuring it out. Congratulations on the quitting smoking!

 

Have you given any thought that the problem might be under the hood. If you have an exhaust leak at the "donut" or a cracked exhaust manifold, the leak would not enter the cabin with the windows closed.
However with the windows open and/or roof off this would allow gasses from the engine compartment to pass thru the firewall.

There are lots of places to get in, clutch rod boot, brake boot, speedo grommet, etc.

 

 

Under the hood was my second guess. But I smell nothing in that area. I checked for holes in the firewall, but it is impossible to get full view with the engine in. I will tackle the astro vent next weekend, as this seems probable.

I guess I could also extend the pipes with a hose to get the exhaust away from the car and then run it at idle. If it still smells in the interior, it must be from up front.

 

Looking at your picture the exhaust appears to be pointing down instead of straight out the side. I had a similar problem with exhaust smoke and it helped a lot by adjusting the output angle.

https://www.corvetteforum.com/forums...ust-smell.html

 

Your pipes are pointing in the correct position for GM Side Exhaust. After market pipes do point more out to the side.

There has to be a simple explanation to your problem as no one else is experiencing the same problem. Your design/setup/installation is no different than any other C3 side exhaust.

Just to clarify, is it "Exhaust" you are smelling or a "Gasoline" smell?

 

Guys,

I think I have the problem solved. I believe Blue1972 earns the 100 points for the solution. What I did was tape up the outlets for the astro vent drainage in the rear wheel carriage. That is where the fumes seemed to circulate and enter into the cabin.

I drove around a little with the windows down, and it seems MUCH better now. The final test will be next weekend with the roof off.

THANK YOU EVERYONE FOR YOUR INPUT!

cheers,
omar

 

I agree with the above completely. This is almost always the case.

Astro ventilation is almost totally ignored, and after a couple of decades or so this stuff rots out.

Your sidepipes should not stink at all unless you are stopped at a light and the wind is blowing your way.

If the astro Ventilation is leaking, then when the window/or top is down a vacuum is caused INSIDE the car that sucks the fumes from the wheel wells straight into the cabin.

You not only have the vents and hoses, but the little water drain. It is supposed to be one way, until it rots out.

 

Looks like you are "closing in" on the Corvette "smoking" problem.

 

They are easy to replace if you can bend like a 4 year old. I would suggest using SS screws instead of rivets. Use black silicone between the tube and fender well. Unless you are going NCRS.

Just be careful a lot of junk will fall out of the tubes..