Exhaust fumes in the cab of my coupe.

[vintrace]

Hi Guys, has anyone experienced exhaust fumes in the cab whilst driving..? My S3 Coupe gets pretty bad at times, windows shut or open. I have tried extending the tail pipe to get the gas a bit further away but no difference at all..
I can always remember my clothes and anything I put in the trunk of my last convertable smelling of exhaust but dont recall it in the cab.... it does make me wear a silly smile after a few miles so it's not all bad...

[69S4]

I do get a bit of that in my S4 fixed head although it's not consistent and I haven't yet worked out exactly what factors govern it. I presume you're talking about fumes coming out of the end of the exhaust and then back into the car somehow rather than fumes coming from the engine breathers or whatever and coming in from the front end. They tend to be a lot more acrid.

My working theory has been that it's just the nature of Elan rear end aerodynamics. I've got the twin pipe silencer and the end of the pipes stick out just beyond the rear bumper so the fumes should get a good start on their journey towards global warming but after a long run I do notice some sort of residue film on the rear end paintwork. My guess has been that airflow round this area is more turbulent than you would think and that the rear of the car is surrounded by a miasma of half burnt petrol residue (the car is still running rich but in pretty good mechanical nick, not using any oil etc) as you drive. Stir this up with side winds or other traffic and some of it occasionally comes in the windows.

I've tried to ensure that the various exhaust joints are sealed to prevent leaks long the length of the system so I'm fairly sure it isn't coming in from there. It has been worse in the past when the engine has needed "refreshing" and oil fumes are mixed in with the petrol based ones I'm currently enjoying. For me it's never been a huge problem, just one of those things that I've assumed will diminish if I ever get the engine set up properly as opposed to just running but otherwise I just live with it.

Stuart

[AussieJohn]

A lot of +2s have this problem, mainly with fumes in the boot, I don't know whether its right but one theory is the flowthrough ventilation sucks more air from the cabin than comes in from the front vents, this then pulls air from the boot with fumes included. I guess the boot seal is maybe the problem, I have heard that someone was going to block the rear flowthrough vents to stop the fumes but I didn't hear the results.

[SADLOTUS]

Hi all, my DHC did the same, anything in the boot smelt like I'd dried it by running exhaust through it.

I think I've sorted it - it's not so bad now. I put chalk along the boot seal to show where it touched the boot and didn't, then put draught excluder (can't tell you what kind - found it in the garage - about 5mm square and ran it along the chalk line on the inside of the boot. Seems to have made a better seal. My boot is not a good fit, I should experiment with different seals but this temporary fix works for me, it confirmed what I was thinking.

Can only smell the oil dripping on the exhaust now.

[Old English White]

... That Stuart & Cie explain about aerodynamic is the main reason .
The shape of the rear end of the Elan with its straight cut and recessed tail surrounded by edge is a real booster for good aerodynamic and acting for hight speed but if the exhaust tube is too short , it can transform every tour in potential nightmare ... Every body notice that this aera was prone to be dusty , oily & smoky .
Make sure that it is longer than the overall length , assuming that there is no other gas leak and from S3 & S4's , verify the boot rubber (getting flat with time)... It's the only relief for a car made 40 years ago .
Christian.

[bcmc33]

I'm sure the explanations are correct - the easy way to prove it is to seal the boot gaps with masking tape to see what affect it has.

If you've ever driven a hatchback with the rear gate open you will know how much exhaust gases can enter the car.

[ianf]

You have probably checked already but a tear in the gear lever gaitor can let fumes in.

Ian

[mac5777]

Hi Vintrace, when I restored my coupe and replaced all of the seals, I had to try several different seals to get the doors to close without bulging out on the corners. I also had fumes coming in from the boot. I solved it by installing a tight all around seal. The seal needs to be tight enough to over come any vacuum effect at speed.
Brian's suggestion of taping the the lid shut and don't forget any other holes on the boot floor. Fumes can only get in through holes or leaks. Then if you are still smelling fumes, you'll know that it is not from the boot
Hope that helps.
Sarto

[Spyder fan]

It's almost certainly the seal to the boot area.
My +2 had a faulty/weak boot catch that would pop open after a few miles, I always knew when it had happened as I could smell exhaust fumes almost straight away.
The boot if it doesn't seal becomes a low pressure area when the car is moving, it will suck in outside air and if that happens to be tinged with exhaust fumes..... well thats what you are getting. This isn't unique to Elans, it happens to all cars that don't have airtight sealed boots from the cabin, try picking up a large item from your local DIY store with the hatchback open in your modern Eurobox and you will get the same effect.

Regards

[vintrace]

Many Thanks guys... I did suspect a boot seal but mine looks great... however looking great is not sealing great... the chalk idea sounds good will give that a try... I do have a couple of holes in the boot floor also I can easily seal up...
Really is unpleasant... so my first priority...
Thanks again..

[donselan]

Unpleasant..and potentially dangerous. I found that after a time in my coupe not only did my clothes smell but I started to develop a headache. What finally worked for me was, first to follow all of the above suggestions about sealing the floor, boot, shift gaiter etc and second, ensure that all of the exhaust joints were completely tight. I have even wrapped some of that silver exhaust sealer tape around the joints to ensure a seal. It works well but does require renewing before each driving season.

Don
36/5607 coupe

[alan]

hi everyone,
please don't forget to look behind the numberplate on plus2s for a hole. maybe someone in the past had the boot release cable snap. if this happens the only way to open the boot to replace the cable is to drill a hole behind the numberplate. you then use a screwdriver to release the mecanism. this was the problem on my plus2 and the previous owner hadn't plugged the hole. just the thing for letting fumes into the boot
Alan.b

[avhation]

After years of trying to improve the boot lid seal by various means, my ultimate fix was to build up with fibreglass the lip of the boot aperture at the rear corners where the seal was not making good contact, as shown by the soot marks.

[rennbaron]

...

the next thing i have to fix, after a pleasant drive on empty backcountry roads today,
my wife asked about the smell of my clothes..and what kind my business date was..

my three year old son did know )

so, fume in a fhc is a serious problem!

christian

[vintrace]

Thought I would share what I have been up to so far... I cleared out my boot and sealed a couple of small holes... then taped the boot lid completely... went for a drive with mixed results.. with the windows closed it's perfect.. not a whiff of exh gas.. windows open it stinks something awful running along at 50 to 60 mph.
Did the same thing again with the tape off... windows closed it was fine.. windows open got the same result... which I suppose is telling me something...! Not sure what other than don't open the windows..!