Air Dams, Spoilers and Exhaust Fumes

[MDyer]

Have any of you added airdams and/or rear spoilers and noticed any improvement in the exhaust fumes?

I'm almost finished adding mine, and I'm hoping against hope that there is going to be an appreciable difference. (If so, maybe my wife and daughter will go for a ride; they're actively boycotting the Z because of it. My son, on the other hand, could care less!)

[2ManyZs]

It might, and it might not....

If it works the way it's supposed to, it shouldn't leak any worse than before... best thing to do is start sealing the leaks....

[Ken]

Mike:

The largest source of fumes comes from the hatch seal rubber gasket. Take a playing card, place it between hatch rubber and hatch and close the hatch. You should not be able to easily remove the card. Remove the interior trim (tail light, vapor tank) and check the openings where the vent hoses from the gas tank come thru the floor. Check hoses. Also check taillight gaskets and the inside cover trim on your hatch. Idon't believe that a spook or spoiler will make that much difference if air (exhaust) can get into the car.

Remove center counsel and check the two rubber boots sealing the shift lever and the boot sealing the lever to body. In the firewall make sure all thru openings(wires, hoses, cables) are sealed.

Does your exhaust pipe extend out just beyond the rear bumper?

If all of these areas (and your door gaskets) are good, you should have no more problem with exhaust fumes.

Ken

72 240Z

91 300ZX

[MDyer]

I haven't started the sealing process (or checking it for that matter) yet.

My understanding is that the aerodynamics of the car naturally create a vaccuum, and hence the fumes. Even if the car is sealed up, don't the fumes still come in through a window (if open)?

I was hoping that the aerodynamics would change just enough to eliminate the vaccuum...

I'll try your advice!

[Ken]

Mike:

I use a spook to keep downward pressure on the front wheels. I don't have a spoiler on the rear (although I have been tempted to get the BRE period...just can't think of drilling holes , to mount it, on the hatch).

Last year I had occaision to drive from New Hampshire to York, Pa.

The temperatures were well over 100 degrees F during most of the trip (Hartford,Ct 106 F). My 240 became a 280 (two windown wide open(no a/c) and 80 mph! I had no problem with exhaust fumes. Nice breeze except when I would stop in a rest area! My exhaust pipe does extend a few inches beyond the rear bumper FWIW.....

Ken

[frankensteinZ]

I get the same thing with my girlfriend's (plural). HAHAHAAAH I wish. Seems none of my friends mind riding in fumes. I have had the seals on my list for a while, but to tell you the truth I kinda like it. Those combined with the half rusted exhaust, and less then quiet interior, make for an almost nascar experience.

Frankenstein Z

[2ManyZs]

Mike, I'd start on the leak issue before you worry about a spoiler to stop the fumes. The spoiler will change the aero of the car, but you will still have a low pressure area behind the car which will create a vacuum and still pull the fumes into the car. All the spoiler does is change the shape of the vacuum behind the car, not get rid of it entirely. The spoiler will use the airflow over the car to create a little bit of downforce on the back of the car and and only move the swirl of air that swirls down to the rear further back from the rear of the car before it joins with the air that comes under the car and then circles back the rear of the car...

Hope you can understand what I'm trying to say here....

Here's a pic with a diagram of the airflow that might give you a better idea..

[MDyer]

The reasons for the spoiler are more cosmetic and performance... I was just hoping it might help that as well! Thanks for the input and the pic 2many

[ZmeFly]

you want to search for the leaks to fix the problem rather then try to work around it.

usually it is the hatch seal, tailight seals, and the vinyl piece on the hatch, also check and replace if necessary, the rubber gromets in the spare tire well and the hatch also, plus the fuel tank vent line rubbers

good luck

[2ManyZs]

Or you could have someone follow you in a "Nascar style" draft 3 inches off you rear bumper and you would have no vacuum at all on the rear of your car, well, maybe that wouldn't be the best idea huh?

[Mr Camouflage]

Spoilers wont reduce any fumes getting into the car. tho only way to do it is fix the seals.

My had a problem its fumes. I knew it when i bought it because i could smell it when i test drove it. I bought it anywan because i wasn't going to drive if before stripping and rebuilding the car.

The cause was loose tail lights, and a missing tail light seal on the light above the exhaust pipe.

You could try gaffa taping up the rear hatch, tail light pannels and tail lights untill its air tight. very ugly but it would work.

Just keep a knife and a roll of gaffa tape in the car incase you have to open the rear hatch while you are out......

...Well thats what you tell the police it's for when they stop you.

You end up with a low pressure area behind the car where the exhaust is so it gets sucked along with you. and if you have your windows open it also creates a low pressure in the car which sucks the exhaust into the car. Which is in part why people get sucked out of aeroplanes if a window breaks.

[Murph]

I found the main culprit in my zed was the tail light seals. Sealed around them with a non-hardening sealant and now the problem is mostly gone.