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Full Version: Why do I smell exhaust in my van with back windows open?
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I have a '96 Dodge Ram 1500 with rear windows that flip open a few inches at the bottom.  During the summer I would like to keep them open for air circulation, but when I do while driving, I smell car exhaust fumes inside the van!  The exhaust pipe is at the rear left side of the van.  When I close the windows, I don't smell the fumes.  How is this possible if the van is moving and I'm theoretically leaving the exhaust behind me??
Because as you drive along, a vacuum is created at the back of the van. That is where the exhaust fumes end up and in your windows. It is also why the back windows get dustier than the other windows.
The aerodynamics of a van are creating a funnel at the back of the van for the windows to suck in the exhaust fumes. That's why we always recommend never driving with your rear windows open.

Here's some info on air turbulence:  http://www.explainthatstuff.com/aerodynamics.html

At the very bottom is a diagram of air in motion on a box truck that would be very, very similar to what happens at the back of a van.
(05-24-2016, 06:22 PM)FuManchu Wrote: [ -> ]I have a '96 Dodge Ram 1500 with rear windows that flip open a few inches at the bottom.  During the summer I would like to keep them open for air circulation, but when I do while driving, I smell car exhaust fumes inside the van!  The exhaust pipe is at the rear left side of the van.  When I close the windows, I don't smell the fumes.  How is this possible if the van is moving and I'm theoretically leaving the exhaust behind me??

Use the side door windows,
this used to be common knowledge. I guess not anymore. never leave your back windows open while driving. this brings up another point, on a computer controlled vehicle you should not smell exhaust. if you do you have other problems. highdesertranger
Thanks everyone! I've never been all that automobile-savvy, so it's not too much of a stretch for something like this not to be common knowledge for me. I feel a bit sheepishly dumb right now... Smile
I didn't mean it that way, but after reading my post it might be taken that way. I am sorry about that. still you really shouldn't smell your exhaust. highdesertranger
If you can find an air dam that mounts to the very back on the roof, it deflects wind down into the vacuum and theoretically should keep your back window clean and exhaust from coming in.

Anyone ever seen one for a van?
Bob
you can build a camback if that is what you mean by air dam the idea is this moves air out at the proper angle (12 to 15 degrees) and releases it instead of having it roll back, I got one on my kurb and also one on my Toyota not sure how well they work but windows stay relatively clean ,mpg have improved on the Toyota, you can also use a rear sloping belly pan at about he same angle the idea behind all this is that you create the start of a teardrop and have air move out towards the point instead of swirling around and creating drag. You would never know how well you do exactly unless you had a wind tunnel to test it but can have fun trying.
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