Fumes 69 FHC

[johng]

I'm getting exhaust fumes in the cabin. I have checked the obvious and by elimination have discovered it happens when the door window is open. This (I think ) means it is sucking exhaust fumes from the rear. As I like to drive with the window down is there a cure for this vacuum effect ? 69 Series 2 FHC

[drcarrera]

As you've checked the obvious, so presumably the exhaust from the manifold to the rear pipes, the only other possibility I can think of is the boot not shutting properly and fumes are being drawn in that way.

I drive my S2 FHC with the windows open a lot and haven't experienced fumes in the car.

[Simon P]

I drive my S2 FHC with the windows open a lot and haven't experienced fumes in the car.

Ditto

[mgcjag]

Hi.....how long have you had the car? Has it allways happened or something new....do you have any leaks in the exhaust.....what tail pipes do you have.......do you get the fumes if you close the window.....could if be oil on the exhaust fumes comming from engine bay or under car........

[Heuer]

Check the fit of the heater box seal against the bonnet intake duct by using talcum powder as a witness mark. It will only take you a few seconds to do. You may find the foam seal is not touching the front of the heater box so allowing engine fumes directly into the cabin. My investigations into this suggest the repro heater boxes have the volute (round bit) welded slightly tilting downwards instead of level. I cured mine by fitting 1/8" spacers on the lower fixing bolts to lift the box. You will need to experiment as a small amount of adjustment at the bulkhead will mean quite significant movement of the volute.

[Nickleback]

Had same problem on my S2 FHC and it was two issues, first being a perished rubber seal around the back door drawing in exhaust fumes and the second was the large rubber grommets / seals on either the side of the gearbox housing / tunnel under the carpet & underfelt were missing / damaged allowing fumes in from the tunnel.
Worth checking as it may help find the issue for you

[johng]

Many thanks to all for your suggestions. It gives me a lot to think about and check. Thank you again. John G.

[Heuer]

I moved this thread here from the Welcome section as it is more appropriate.

[PeterCrespin]

I moved this thread here from the Welcome section as it is more appropriate.

Quite so. In polite society, it is considered rather outr? to discuss grommets on a first date...

[paulsco]

Not wanting to hijack the thread, but my attention was drawn to David's (Heuer) comment about the heater seal possibly sucking in engine fumes.

The oval door on the bottom of the heater box is open to the engine bay isn't it?

I have not driven my car yet; I am still restoring it, but I always thought drawing air from the engine bay rather odd, or have I got this completely wrong?

Paul

[PeterCrespin]

Er, yes you have.

When the flap oval hole underneath is open, it's because the heater airflow flow is cut off - ergo no fumes and the bonnet duct vents into the engine compartment through the casing. When the flap covers the lower hole the heater matrix is exposed and takes air from the bonnet duct through into the cabin, not the engine compartment, ergo still no fumes.

As Baldrick would say, 'A cunning plan!'.

[paulsco]

Thanks Pete; that explains it.

I too have a cunning plan to bring this back to the original topic.

What if the heater door seals are perished or not sealing properly.
When the heater motor is not running and perhaps the widows are open, the air pressure under the bonnet could easily leak through the heater door seals and into the cabin?

Paul

[Heuer]

Actually not so cunning. With the flap half open, or indeed anywhere between fully closed and fully open, air could be drawn in from the engine compartment. I always have mine at either extreme, never in the middle.

[mgcjag]

If its exhaust fumes then unless you have a leak in the exhaust system fumes will only come from the tail pipes......does it happen when the car is not moving......if so then extend your tail pipes with some hose etc as far away as poss then you have eliminated the fumes comming in from the tail pipes.........and could just be burnt oil fumes, wrap a bin bag around the heater box to eliminate anything comming in there.....now check all the gromet holes in tne bulkhead/ tunnel......

[Fixed Head]

johng, your question here really made me laugh. That's because some years ago, I used a series 2 fhc for about 40,000 miles of everyday driving, including some extended traveling, and one trip alone of almost 14,000 miles. During this time I was never able to completely solve the problem of exhaust being pulled into the car from the rear hatch/boot area. In fact I almost got rid of the car at one point for this reason alone.

This is not an unknown issue with e-types. I'm pretty sure there are some complaints about it on record from when the cars were new. I've also travelled in roadsters where clothes and luggage in the boot ends up smelling like car exhaust when you reach your destination. And this is in cars with no exhaust or oil leaks.

Concentrate on checking the area around and under the rear bumper and boot. Make sure the grommets are all in place to the reverse light wires and behind the taillights, etc. As I recall there are some plugs that go in holes on the horizontal panel just under the bumper. Make sure they are in place.

Most importantly, check the fit of your rear hatch and the condition/fit of the rubber seal. Try shutting a sheet of paper in the bottom part of the lid. Can you pull it out without resistance? That could mean the seal isn't contacting the lid well, leaving a gap to pull in exhaust.

Hopefully you'll have better luck with all this than I did.

[paulsco]

Over the years I have seen many comments posted about exhaust down pipes working loose and causing fumes. I remember there being a discussion on JL about using different types of fixings to prevent this. Also I do not think the flexible joints are completely gas tight, plus engine fumes are just as bad. The heater is very close to the down pipe joint.
Paul

[PeterCrespin]

Actually not so cunning. I always have mine at either extreme, never in the middle.

This is because it's an on-off switch that is spring-loaded to be, er, on or off. My current exemplar is seized (clearly heat was not often called for in SoCal) so I can't check, but when I had working cars I seem to recall it clanged shut in either direction. It may look like a graduated control but it's marked on or off and it just happens to be a mechanical quadrant operated sprung over-centre action. No?

Of course the clanging was a cunning built-in audible warning signal that the micron-thick layer of friable foam was no longer serviceable, and your sealing comments apply.

[Heuer]

It was a spring actuated toggle on the 4.2 cars but on the 3.8's it is a graduated control with the spring merely acting as an assisted return.

[paulsco]

Fixed Head?s comments are interesting. Over the last 20 years I have spent a great deal of time trying to stop fumes getting into my 340 Jaguar.

I must have an insensitive nose, because I wasn?t sure if it was exhaust fumes, petrol fumes, engine fumes or a combination of them all.

I?m sure I still have petrol fumes in the boot, or is it exhaust?

I?m the only one who seems to notice them, but it spoils my enjoyment of the car and I have lost the will to keep on looking.

If I have the same problems with the E when I have finished it, then I?m going to sell it and get a push bike.

Paul

[Fixed Head]

Ah, but Paul, maybe you're just looking at this wrong...

Isn't that part of the fun of owning a vintage British car: Being able to smell those exhaust fumes, petrol fumes, engine fumes, or the delightful combination of them all?