Exhaust smell in cockpit of GTM

[Ricker]

Am looking at purchasing a GTM. Took a drive in one the other day and noticed exhaust fumes in the cockpit area. Gave me a headache in about
5 min. Is this normal for this car? Is there away to seal the cockpit area to keep this from happening? Love the car but can't drive it like that. Any comments?
Thanks

[LCD Gauges]

This is a huge problem for most builds. There are many openings along the firewall and underbody of the GTM. I find the most difficult place to seal is around the waterfall (water pump cover) between the seats.

I've done a decent job of cutting exhaust fumes, but there is always room for improvement. It's probably a good idea to use a fire-rated silicone around all firewall panels, screws, rivets, etc. The seal along the roof line and side panels could also use a bead of caulking.

It would be great to install some sort of membrane *(poly?) over the waterfall tubing and seal it (caulking and/or gas proof tape).

I'll be addressing this again as the left side fuel tank needs to be installed over the Winter. If I remember, I can link to this thread or
post photos of my ideas.

[kabacj]

fast and easy way to make the cockpit air tight is to use foil tape. The stuff used to seal HVAC systems. It’s possible to seal everything up using the kit parts if you are careful but foil tape covers a multitude of sins is waterproof, fireproof, and air tight.

[VRaptor SpeedWorks, LLC]

I've never experienced that with any of our builds here. Yes, the key is planning and sealing. If you're sloppy in sealing things up, then you will have issues. Every little gap needs to be sealed.....along the roof line, the little alum close-out panels that span between the chassis and body next to the fuel tanks needs to be 100% sealed to the body and the chassis, cockpit sidewall panels behind the door openings, under the stereo, around the AC vent tubes, the footwell panels under the dash, etc. Keep in mind that the air from the engine bay (with the exhaust fumes) get drawn forward into the tunnel and exit out the front of the tunnel, so everything in the tunnel needs to be sealed. All of that needs to be done during the build. Most of those places are not accessible on a finished car, so you need to get all of that stuff sealed up as you're building....not after it's all done.

This also points out the need for getting the most airflow thru your engine bay as possible. If the exhaust fumes are that strong, it tells me that you have very little air flowing thru your engine bay.....getting the hot air out and fresh air in.....all of the heat and exhaust fumes just swirl around back there. As I mentioned above, the tunnel pulls air from the engine bay, so it sounds to me like you have lots of negative pressure in your engine bay, which sucks the exhaust back into the engine bay and then forward up thru the tunnel. With proper venting of the engine bay (lots of paths for fresh air to get in and lots of paths for hot air to get out) there is no way for the exhaust fumes to build up in the first place as they will be "blown" out of the back of the car instead of being sucked in.

[crash]

As I recall we only had an issue when the header flanges did not seal properly. We have done a lot of work to get those to seal and stay sealed. We drive the car for hours at a time at a much greater percentage of full throttle than most GTM drivers and do not have this issue. If we fill our fuel tanks 100% full it smells like gas in the cockpit, but we don't have any issues with exhaust.

[eseethal]

My GTM is not sealed very properly, but I never had any problem with exhaust fumes in the cockpit. Fuel smell yes, when the tanks are full and/or driving hard. I can smell the engine, the oil and when the headers warm up but never exhaust fumes.

Eugen

[beeman]

In my many years on this forum, I've never heard of this being an issue. Probably an exhaust leak. I don't think the exhaust in your wake could return to the cockpit.