Exhaust fumes in car

[wildy55]

Hey

Slowly getting high on the fumes in the cabin – only happens when the windows are down. Who's got the skinny?

[sexual_sushi]

Exhaust fumes are one of the most widely discussed topics on any z forum. Try a search and start with your tailight gaskets/hatch seal

[nat0_240_chevZ]

drive around with the engine off.........

or close your hatch......

[reverendzed]

Yep tail light gaskets are the big one, I renewed them and had significantly better results and then added a rear bre spoiler and ...NO MORE FUMES!

Rev.

[MaygZ]

Hey

Slowly getting high on the fumes in the cabin – only happens when the windows are down. Who's got the skinny?

 

Driving with the windows down creates a vacuum in the car - or at least a lower air pressure.  It's how carbies work (venturi effect) and planes fly (Bernoulli's principle).

 

Basically air running down the sides of the car must change direction and therefore speed up.  As it increases speed it also decreases air pressure.  As the air pressure outside the open window is lower than that inside the cabin, air will pass from higher cabin pressure to lower outside pressure in an attempt to equalise pressure.  This has the effect of decreasing pressure in the car.

 

So now the cabin pressure is lower than atmospheric pressure and requires air to enter the cabin to equalise pressure.  It usually finds this higher pressure air at the rear of the car, as that air has slowed down and increased in pressure (interestingly this slowing down of air at the back creates a lot of drag that slows down the car - it is also an area that NASCAR drivers know well as it will genuinely suck the car along if you get into someone else's low pressure area).  Anyhow ...

 

How to stop sucking in exhaust fumes:

1. wind up the windows - stops the air draw from the cabin;

2. take out the windscreen and open the rear hatch - stops the air changing direction;

3. extend your exhaust until it is outside this high pressure area - push it out the side into the low pressure area (one of the reasons that race cars push the pipe out the side of the car)

4. seal the back of the car properly - might make your ears pop when driving though;

5. don't drive above about 20km/h;

6. drive with a dedicated air supply to your face (again something you see in race cars - particularly tip tops - and you thought it was only to cool them down); or

7. open your front vents - allows air to enter from the front under a higher pressure than the back.

 

Good luck and I hope this 'skinny' answers your question.

 

[wildy55]

Thanks, have just put a hammer to every bit of glass on the car. Now smells fine, but how do you get bugs out of your teeth?

[MaygZ]

Thanks, have just put a hammer to every bit of glass on the car. Now smells fine, but how do you get bugs out of your teeth?

 

1.  drive with mouth closed

2.  drive in reverse

3. place poo and UV light in passenger seat and all bugs go there 

[nat0_240_chevZ]

seal up hatch, rear floor pan (check for rust or grommet holes, along with holes in exhaust)

seal up tail lights as mentioned above, bre lips do divert the back wash off the rear lip and tumbles higher away from the exhaust in your wake,

 

use bigger hammer.....

[Zedman240®]

That's gold Simon, you should work at a Zed help call center.

[Roberto]

This was posted yesterday on HybridZ by "logr".  This could be the answer we have all been searching for........

 

I searched but couldn't find this anywhere so thought I would pass it on.

I have been fighting exhaust in the cabin on my 240 but only when driving with a window down. It has been driving me crazy and from my searching, it is common and usually accepted as part of owning a Z.

I have an SR that is fuel injected and clean burning, getting over 30mpg.

The exhaust goes to the stock location.

The hatch seal is new.

The tail lights are sealed.

All holes are sealed.

It still smelled very badly with a window down UNTIL

 

I found the rear frame rail that runs side ways under the tail lights was not sealed underneath the car anymore. It is still sealed into the cabin from the top but after much checking I found that there is a hole on each end(rearmost part beside the tail lights and inside the side panels but all the way at the rear bottom)of the rail. You can not see it but you can feel it on both sides. I stuffed some plastic sheeting in both ends to seal it off. This is the same tube that the rear tie downs are bolted into. I blew air into one of the tie down holes and felt it come out the bottom of the car and out of both ends inside the car. That is what convinced me to close off the ends. It solved the exhaust smell completely.

 

I CAN DRIVE MY Z WITH WINDOWS DOWN AND NOT SMELL EXHAUST. HIP,HIP,HORRAY

[SS30RR]

Bre spoiler makes the biggest difference once you've done all the seals.

 

 

[Six_Shooter]

I think my spoiler may have made the exhaust in the car smell worse.

 

Still searching for a solution.

[gav240z]

This was posted yesterday on HybridZ by "logr".  This could be the answer we have all been searching for........

 

I searched but couldn't find this anywhere so thought I would pass it on.

I have been fighting exhaust in the cabin on my 240 but only when driving with a window down. It has been driving me crazy and from my searching, it is common and usually accepted as part of owning a Z.

I have an SR that is fuel injected and clean burning, getting over 30mpg.

The exhaust goes to the stock location.

The hatch seal is new.

The tail lights are sealed.

All holes are sealed.

It still smelled very badly with a window down UNTIL

 

I found the rear frame rail that runs side ways under the tail lights was not sealed underneath the car anymore. It is still sealed into the cabin from the top but after much checking I found that there is a hole on each end(rearmost part beside the tail lights and inside the side panels but all the way at the rear bottom)of the rail. You can not see it but you can feel it on both sides. I stuffed some plastic sheeting in both ends to seal it off. This is the same tube that the rear tie downs are bolted into. I blew air into one of the tie down holes and felt it come out the bottom of the car and out of both ends inside the car. That is what convinced me to close off the ends. It solved the exhaust smell completely.

 

I CAN DRIVE MY Z WITH WINDOWS DOWN AND NOT SMELL EXHAUST. HIP,HIP,HORRAY

 

Don't suppose he shared images of what he was on about?

[Six_Shooter]

Don't suppose he shared images of what he was on about?

 

None, from the description it sounds like, he just talking about the threaded holes where the cargo straps screw into.

 

If there are screws in those holes, I don't think this idea applies.

[SS30RR]

just play around with the hatch lock position and align it so that the hatch locks very tight. i.e You kinda need to slam the hatch to get it to lock down. Provided the hatch seals is ok I'm sure this will reduce a lot of the exhaust smoke coming in.

[Roberto]

Don't suppose he shared images of what he was on about?

 

Whilst playing around mounting my new exhaust yesterday, I came across what may have been what he was talking about.  The plug that covers this hole had come off and I was struggling with fumes big time.

 

"logr" suggests sealing the holes from both sides as it is in the frame rail.  When I start driving, I will update any progress, but worth checking for a good seal here because it it right on top of the muffler.

[RB30X]

So you're referring to that black rubber grommet on the blue painted surface. Which seals that same chamber that has the similar hole for a grommet underneath?

 

Might check out mine.

[SS30RR]

Cheers I'll do the same.

[53-681]

Install a sunroof

[MaygZ]

Install a sunroof

 

Actually installing a sunroof will be the same as driving with a window partialy down - see my first post in this thread.

 

It will however be sure to contribute to the holes in the floor and the mouldy smell.  This may over-power the exhaust smell - so could work 

[53-681]

Lol all I know is all air/carbon dioxide goes up no matter what. It helps in my Z

[Zedman240®]

Instead of a sunroof, install one of those forward facing hatches like on rally cars; they pressurize the cabin so no fumes get in.

[gav240z]

I think to solve the Z-car fume problem properly someone needs to do wind tunnel analysis. Which can be done on the cheap using the following guides:

 

http://autospeed.com/cms/title_Aero-Testing-Part-1/A_108656/article.html

http://autospeed.com/cms/title_Aero-Testing-Part-2/A_108674/article.html

http://autospeed.com/cms/title_Aero-Testing-Part-3/A_108675/article.html

http://autospeed.com/cms/title_Aero-Testing-Part-4/A_108676/article.html

http://autospeed.com/cms/title_Aero-Testing-Part-5/A_108677/article.html

[Agno]

You don't need to do analysis to know that under the car is a high pressure area and inside the cabin is relatively low in comparison. The solution is just to seal the cabin, that's just a bit tricky given the amount of grommets/holes/vents/deteriorated seals that are in these cars.

 

If you want to be a tightarse you could just extend the exhaust past the rear of the car (drift pipe) and have less fumes.

[Zedman240®]

Just thinking would a side exit exhaust be legal? I know it has to be past a certain distance from an opening window.