The 'E' Type Forum

I have a Series 3 OTS which was converted from a fixed-head, professionally by E-type specialist Butlin Classics. Exhaust fumes are being drawn back into the cabin from the rear. I expect a certain amount from a V12 but this is really bad. There are no leaks as I spent a fortune getting everything sealed and when the roof is up and windows closed all is fine. But as soon as I open a window or drop the hood the exhaust smell is very noticeable. I have wind deflector fitted and it is actually worse with that raised.
The fantail has been moved back as far as possible, but is still not as far as the bumper although I notice it isn't on most others I have seen. Moving the fantail helped a bit but I'm at a loss as to what else I can do. As I am convinced it is merely airflow causing this please can I ask how far back your tail pipes are and if anyone else has suffered from this issue, did you find a solution?
Many thanks!

Hello Raregrin, if you search for “fumes” then in those results for “exhaust” you might find useful information. I hope that might help you find an answer.
BTW, please add your name and car type to your signature, it helps people respond politely and relevantly.

Geoff

Gfhug wrote: ↑

Sun Mar 20, 2022 9:59 pm

Hello Raregrin, if you search for “fumes” then in those results for “exhaust” you might find useful information. I hope that might help you find an answer.
BTW, please add your name and car type to your signature, it helps people respond politely and relevantly.

Geoff

Hello Geoff,

I have already read all there is on the forum about exhaust fumes, but most comments are regarding leaks rather than air disturbance, hence why I am enquiring about this specifically.
I will add my details as you suggest and thank you for bringing this to my attention.

Many thanks,
Peter

Hi Peter,
I suffered from this on my OTS for a long time and tried many things to solve the problem. In the end it was only after driving a long distance over dusty roads that I discovered there are many more leakage paths than is immeadiately obvious. In my case the worst culprit was the rear light units. They have curved backs and the plastic gaskets are rather stiff. Unless the light unit is a perfect match to the bodywork (unlikley) there will be a leakage path. To get a good seal I used non setting widscreen sealant but soft foam might also work. The other culprit was the number plate light fitting. You could try using a smoke genearator to check where there may be problems before taking things apart.
Cheers

Sealing rear lights, may be a solution for a FHC, won’t prevent fumes into the open cockpit of an OTS, or any other old style roadster with streamlined rear; not just Jaguar?
What is your mpg, is there wet black soot in yr tailpipes? I suspect, anyone with >25 mpg and clean, dry pipes may consider this aerodynamic phenomena quite tolerable. When I get there, I’ll know.

The biggest hole in the bodywork is where the convertible roof folds down ahead of the rear wheel arches.... which curve round and are completely open to the boot area.... which has a myriad of small holes at around bumper height at the back of the car.... just above the exhaust fantail.

Gases travel from high pressure regions to low pressure regions. You don't mention what year your car is and whether it has the footwell fresh air ventilation ducts fitted.

kind regards
Marek

MarekH wrote: ↑

Mon Mar 21, 2022 1:15 pm

The biggest hole in the bodywork is where the convertible roof folds down ahead of the rear wheel arches.... which curve round and are completely open to the boot area.... which has a myriad of small holes at around bumper height at the back of the car.... just above the exhaust fantail.

Gases travel from high pressure regions to low pressure regions. You don't mention what year your car is and whether it has the footwell fresh air ventilation ducts fitted.

kind regards
Marek

The car is a 1972, without the fresh air ducts, which I'm sure could help matters. The boot is totally sealed from the cabin and I have recently had a new hood and door seals so there is not much coming in from outside. As mentioned all is now fine while the windows are closed so I do not think there is any leakage. It is only when the windows are open or the roof is down that the fumes are noticeable. This is an early car with a quad fantail and, after speaking with a different specialist this morning I am advised to try swapping them for the later twin fantail and extending them, with fabrication if necessary, to reach as far as the bumper. I am convinced this is an airflow issue and I just wondered if any of you had experience of this.

Raregrin wrote: ↑

Mon Mar 21, 2022 2:16 pm

The boot is totally sealed from the cabin.

No it isn't. You completely miss that the gap above two rear wheel arches where the hood frame is attached reach all the way around to the back of the boot and meet up above the number plate lamp at the boot catch.

Just ask yourself "How did the wiring loom get here?".

kind regards
Marek

Thank you for your input Marek, it is much appreciated
I can't see the gap you mention, which naturally does not mean it is not there in my car. All I can say is that Butlin Classics, who undertook the full restoration of the car and converted it from a fixed-head, have told me that as far as they can tell there are no leaks into the cabin. They have recently spent many hours looking for possible leaks and are confident there are none that have not been sealed. I would hope they checked this gap that you have pointed out but obviously I cannot guarantee that. My point is that since the new roof and door seals were fitted I cannot perceive any fumes when the windows are closed (where I could previously) - would this gap you refer to have any bearing on this? I apologise for my ignorance but it's why I'm asking for help from you knowledgeable folk

Yes as mentioned - there is a huge gap between the inner rear wheel well/arches and the outer body - is nearly big enough to put your hand through and is on both sides. My 71 OTS does not have fumes entering the cabin with the hood up and I have lots of holes in the bodywork around the boot.

The only time I get fumes in the cabin is with the hood down and the relative wind coming from the rear - depends on car speed, wind direction and speed - but other wise no fume ingress.

As suggested try plugging up the holes in the boot area but will be impossible to seal the boot from the cabin.

Best way to discovery as far as leaks is concerned, as mentioned above, get a cheap smoke machine from Amazon, stick it in the boot close the boot and let it rip. you will soon know whether you have any leaks and from where....

And what about exhaust fumes being sucked back from the exhaust because the aerodynamics of the vehicle moving through the air causing a low pressure area behind the windscreen back to the rear of the vehicle hich sucks the exhaust into the low pressure area - may not even go anywhere near the boot.

AussieEtype wrote: ↑

Tue Mar 22, 2022 4:23 am

And what about exhaust fumes being sucked back from the exhaust because the aerodynamics of the vehicle moving through the air causing a low pressure area behind the windscreen back to the rear of the vehicle which sucks the exhaust into the low pressure area - may not even go anywhere near the boot.

It is a possibility except it would affect every OTS yo a similar extent....

AussieEtype wrote: ↑

Tue Mar 22, 2022 4:23 am

And what about exhaust fumes being sucked back from the exhaust because the aerodynamics of the vehicle moving through the air causing a low pressure area behind the windscreen back to the rear of the vehicle hich sucks the exhaust into the low pressure area - may not even go anywhere near the boot.

Exactly that. If you look at someone driving an OTS with the hood down, there hair isn't blowing backwards. If anything, it blows forwards, meaning air is being sucked from behind .

malcolm wrote: ↑

Tue Mar 22, 2022 9:25 am

If you look at someone driving an OTS with the hood down, there hair isn't blowing backwards. If anything, it blows forwards, meaning air is being sucked from behind .

For that to happen, you need hair

Hi Peter,
My car is a 74 OTS with a twin fantail that is set as far back as possible so that it is in line with the rear bumper; it also has the fresh air vents.
It displayed exactly the symptoms you describe. When I first had it the luggage would reek of exhaust fumes after any length of run. There is no practical way to seal the cabin from the boot for all the reasons that others have explained. From the dust trails inside the boot after long drives on dusty roads I could see where the leaks were ocurring at the rear of the car. Sealing these one by one has almost eliminated the problem. The other thing that helped was a cylinder head rebuild with new valve guides, the car has done 110k miles and was burning a bit of oil. A smoke generator in the boot will show you just what is happening and save a lot of fruitless expense based on speculation.
Good luck,

Whitact wrote: ↑

Tue Mar 22, 2022 10:03 am

Hi Peter,
My car is a 74 OTS with a twin fantail that is set as far back as possible so that it is in line with the rear bumper; it also has the fresh air vents.
It displayed exactly the symptoms you describe. When I first had it the luggage would reek of exhaust fumes after any length of run. There is no practical way to seal the cabin from the boot for all the reasons that others have explained. From the dust trails inside the boot after long drives on dusty roads I could see where the leaks were ocurring at the rear of the car. Sealing these one by one has almost eliminated the problem. The other thing that helped was a cylinder head rebuild with new valve guides, the car has done 110k miles and was burning a bit of oil. A smoke generator in the boot will show you just what is happening and save a lot of fruitless expense based on speculation.
Good luck,

Thank you. I will definitely try the smoke test. I am not noticing the smell of luggage in the boot so much as on clothing within the cabin. Did you notice fumes with the roof up and windows closed?
I am concerned that having a twin fantail extended to the bumper did not help as that was part of my plan and one recommended from another specialist who has seen positive results from doing so.

I had the trifecta, luggage, clothes and hair. Never noticed during the drive, only afterwards.

Imo another source of boot leaks is the boot lid seal, if there is a gap for the latch or if the boot lid only lightly engages the seal, etc.

What about sealing between the boot and the cabin using expanding foam, can anyone think why this might not be a good idea?

lowact wrote: ↑

Tue Mar 22, 2022 2:18 pm

What about sealing between the boot and the cabin using expanding foam, can anyone think why this might not be a good idea?

My car had fibreglass wadding in the rear wheel arches and inside the bulkhead. Bear in mind this (and foam) will be a water trap. It is better to have airflow to expel moisture than an attempt to seal. I removed the wadding and simply put grommets into all of the small holes at the back of the car and left the fresh air ventilation permanently on.

Leaving the side windows half up when the top is down is also helpful.

kind regards
Marek

Hi Peter,
With the roof up and the windows closed I did not notice a problem. I think the air vents on the later cars maintain a positive cabin pressure in those conditions. Nor did I notice a problem with the roof down, but I have an air screen behind the seats. However with the roof up and either window even partly open there was alway an unpleasant smell. I agree with Colin that the boot seal also needs to be carefull adjusted and checked. You may be able to cure the problem by moving the exhaust outlet further back but my guess is that it would have to be well beyond the bumper line and would look odd to say the least.
Cheers,