new member-exhaust fumes in interior ???

[240Z-ZZ4]

Its been about 20 years since owning my last 240Z(70 LT-1 equipped). I have just purchased a very nice 1973 Silver 240Z equipped with a 350 ZZ4 crate engine-World CLass T5- R200 rear end-Modern Motorsports Coil overs, 5lug conversion,4 wheel disc brakes, 280zxt CV axel conversion. Now to my problem, which I know is typical w/ early Z cars, exhaust fumes in the interior. It is especially bad with the windows down. My 2 earlier cars had it and so does this one. The rear hatch seals were replaced by the previous owner and are less than a year old. If I remember correctly, it is a areo dynamic problem inherit to the car shape, the fumes actually whip around from the back hatch area to the open driver's window. The fumes are less if the lower pull handle vents are open, but is still pretty bad. THE QUESTION IS WHAT CAN I DO TO STOP THIS FROM HAPPENING? Thanks for any help you can give me!

[DatsunZGuy]

the condition and seal of the rear taillight gaskets. In addtion, some owners also had good luck when they extended the tailpipe past the rear bumper a few extra inches.

[Craig Lovegrove]

Well it's the age old question. Your new car sounds nice. But the fume problem is a univeral one. I think the fumes actually get sucked in through the rear hatch of the car when the window is down. When my window is up I get nothing. I have searched high and low and tried everything and concluded it is the rear hatch. I brought some inch wide or there abouts and 5mm thick single sided sponge rubber tape on a roll. I stuck this to the top of the hatch where the rubbers would seal or touch the hatch. To close the gap. This definately reduced the fume problem. Also I would be sealing up every nut and bolt hole in you rear of the hatch including floor etc. I cut small pieces of aluminum and siliconed them over these misc holes. Quick, easy and cheap. Even over the two large bolt holes between the rear struts. Hopefully the rea lights are sealed pretty well and you should get rid of 80-90% of the problem.

[240Z-ZZ4]

the condition and seal of the rear taillight gaskets. In addtion, some owners also had good luck when they extended the tailpipe past the rear bumper a few extra inches.

Thanks for the info. I have dual spin tech mufflers with tailpipes that extend past the bumper. I just read past threads on this subject and think I have a handle on what to do. It looks like I will be crawling around the interior of my car this week end and taking a better look at the rear hatch and rear light seals. Although, I'm not so sure I want to fix this problem. My wife probably will not want to drive in the car with the fumes--Drive fast, with fumes, no wife---Drive Slow, no fumes, with wife. Tough One!

[=Enigma=]

Don't let that stop you. Carbon monoxide poisoning is a slow and gradual thing. Over time the poison builds up in your system displacing the oxygen in your blood and can be harmful to your heart, brain and other vital organs. Normally this is only an issue if you drive fairly often such as every day or every other day, and obviously varies with the level of exposure. Better to be safe.

[justaZcarguy]

I would check the taillight seals, that has been the problem in most of the z's that I've had.

Another area is the where the hoses associated with the fuel tank are located, sometimes I hear of those being breached, usually this is more of a fuel smell...

I would check the area around the taillights for gaskets / holes on the rear tail section.

I can remenber having to blast the blower motor to get positive cabin pressure to avoid fumes in one car.

Now about the poisioning, kittys are furry.

Hope you find it!

Keep us posted.

~Brian

[Carl Beck]

With new hatch seals -

1) make sure they are all new - the large inner one, and the three smaller outer one's.

2) Place a dollar bill between the seals and the deck lid - close the deck lid.. the dollar should be hard to pull out. If it slides out easily - adjust the hatch lid tighter to the body. You have to do this all the way around the hatch lid/body. Many times the hatch lid is slightly warped...

Sometimes - it isn't exhaust gas - it's gasoline vapor/fumes. In that case you have to replace all the vapor recovery lines in the back of the car - or eliminate them and seal the holes. Sometimes the OEM rubber seals around them, on the inside of the car are cracked and leaking exhaust gases.

Yes - the tail light seals do harden over time and fail.

The rear tail gate vinyl finisher on the 71-73 240-Z's needs to be in place and the seal around it has to be replaced. The foam rubber originally used 35+ years ago simple desolves... You have to remove it and clean the area and replace the foam rubber seal. Other wise exhaust gases come in through the latch itself...

Yes - because of the aerodynamics of the Z - the exhaust gases are flowing from the relatively high pressure area behind the tail lights, into the relatively low pressure area in the cabin. When you roll the windows down, the air flow over the sides of the car, past the open windows, acts as much the same as air flow over a high chimney - it pulls air out of the cabin, thus lowering even more, an already low pressure area. Opening the floor vents in the kick panels as well as the Vents in the Fresh Air/ Heater helps to force air into the cabin thus raising the relative pressure in the cabin.

The bottom line is that exhaust fumes in the cabin was never a problem when these cars were new.. so we have to know that it can be eliminated if enough time and effort is put into it.

Adding the BRE Style rear spoiler also helps reduce exhaust fumes in the cabin, because it moves the relatively high pressure area behind the car - farther back away from the tail lights.

It can be fixed so don't put up with it..

Good luck -

Carl B.

[Mike]

Is carbon monoxide a problem when driving? I was under the impression that carbon monoxide is heavier than air and doesn't get into the car while in motion.

[=Enigma=]

Is carbon monoxide a problem when driving? I was under the impression that carbon monoxide is heavier than air and doesn't get into the car while in motion.

Doh!!!!!

[chris b]

Thanks Carl. My problem has been petrol fumes and I suspected but couldn't find any firewall leaks. I hadn't considered that they could be coming from the rear of the car.

Cheers Chris

[justaZcarguy]

Hey Carl!! Been a long time, hope you have been well!!

I've never adjusted the hatch to have a tighter seal...

I take it this is done in the latch assembly?

Thanks

~Brian

[justaZcarguy]

Oh, and Chris, Welcome to the club!!