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Rob Y

Exhaust fumes smell in boot - solved

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Hi, while reading this discussion, I have exactly the same problem with my TR6 (carb supercharged). Fumes smell in the cockpit and more on the righthand side.

I sealed off the rear pannel completely with plastic and silicone. Sealed off all rear lights in the boot, tested and checked carefully the boot rubber sealing.

A very small improvement. But it starts again while driving over 35 miles/h.

It comes definitely from the back as there is no smell in the engine compartment.

A complete headache !!!

Thanks in advance for any "new" miraculous solution !

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Garage where i bought mine in uk told me ...welcome in oldtimers word.... i suggest you to pack everything in garbage bags in the boot...for the moment i don t i find it funny but i know I will do it one day :-)

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Suggest inspecting the front bulkhead.    A dark garage, one with a torch in the foot wells, one looking under the bonnet (you decide who!) will find where the grommets etc have failed.

Also and similar method, the gearbox cover to floor seal.

JOhn

Edited by john.r.davies

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but this dosen't stop the smells in the boot getting into the suitcases etc.

i renewed everything on my 5 but it is still there. Still on bin bags and no food in the boot.

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The rear lamp units have 2 sets of seals:

1) lenses to lamp body

2) lamp body to rear valence.

They are not perfect seal. What sealant can best be used for this?

Or should new seals do the job if carefully installed?

Waldi

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As someone has already said if the engine is right and fuel mixture is correct there is no smell 

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But aren't the PI engines always on the rich side?

If there are no exhaust smells in the engine bay (and there shouldn't be) then why not tape up the boot lid and any other gaps at the rear and what happens.

Boot seals are notorious for being slightly better than useless.

The sharp square finish to the back end of the TR6 doesn;t help airflow to easily slip away

 

Roger

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1 hour ago, RogerH said:

But aren't the PI engines always on the rich side?

If there are no exhaust smells in the engine bay (and there shouldn't be) then why not tape up the boot lid and any other gaps at the rear and what happens.

Boot seals are notorious for being slightly better than useless.

The sharp square finish to the back end of the TR6 doesn;t help airflow to easily slip away

 

Roger

Roger you have not been in one set up right then 

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Hi Neil,thanks, I like that, no action then with dirty sealant. I will first wait how all is once I drive her, hopefully this year.

Cheers,

Waldi

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16 minutes ago, ntc said:

Roger you have not been in one set up right then 

Hi Neil,

I have never been in one but I've been behind many and they are all rather smelly.

 

Roger

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The back of the TR6 is more square than earlier TR's. This may cause the exhaust fumes to swirl around the back of the car more than a TR4 or 5. The solution may be to experiment with the length of the exhaust tailpipe. Having a good boot seal and good rear light seals is obvious. It would be interesting to put a 6 and a 5 in a wind tunnel to see how the exhaust fumes behave. Failing that maybe stick some Redex into the carbs, drive along with someone in a car behind and see where the smoke goes. I used to demonstrate air flow around doorways in clean rooms using a portable smoke generator. It was amazing what we learnt about air movement using this simple technique. I extended the exhaust pipes on my twin exhaust on the TR4A. Before I did that the back of the boot and the bumper would collect water droplets and soot particles from the exhaust.

Keith

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5 hours ago, Waldi said:

Hi Neil,thanks, I like that, no action then with dirty sealant. I will first wait how all is once I drive her, hopefully this year.

Cheers,

Waldi

Waldi

Most fit the boot seal incorrectly just whack it on and that is not the way to do it 

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I had fitted new boot and light seals but the most effective solutions have been Wind break and Tail pipe extensions.The extensions are temporary until I can fit a new bespoke rear section with slightly longer tail pipes.Pipes not to every ones taste but no smells. Must get the mixture check then perhaps the pipe extensions can come off.:)

48.jpg

49.jpg

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Ntc what is the correct way to fit the boot seal on please? I'm a newbie and am slowly fully restoring my car so it would be good to get your advice as I know from other TR Register folks that you are a great fountain of knowledge. 

Michael

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Hello Phil H 4.

Can you advise where you purchased your wind break?

I’m interested for two reasons.  Possible fuel smell elimination as well as hopefully, less hair ruffling.  Not mine.

Cheers!

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On 1/10/2020 at 8:05 PM, michaeldavis39 said:

Ntc what is the correct way to fit the boot seal on please? I'm a newbie and am slowly fully restoring my car so it would be good to get your advice as I know from other TR Register folks that you are a great fountain of knowledge. 

Michael

Hi Michael, I’ve have my seal fitted with join at the centre rear closest to the petrol cap. As I see it it’s further away from the exhaust. Not sure if this is what Neal (NTC) means.

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On 1/9/2020 at 3:32 PM, keith1948 said:

The back of the TR6 is more square than earlier TR's. This may cause the exhaust fumes to swirl around the back of the car more than a TR4 or 5. The solution may be to experiment with the length of the exhaust tailpipe. Having a good boot seal and good rear light seals is obvious. It would be interesting to put a 6 and a 5 in a wind tunnel to see how the exhaust fumes behave. Failing that maybe stick some Redex into the carbs, drive along with someone in a car behind and see where the smoke goes. I used to demonstrate air flow around doorways in clean rooms using a portable smoke generator. It was amazing what we learnt about air movement using this simple technique. I extended the exhaust pipes on my twin exhaust on the TR4A. Before I did that the back of the boot and the bumper would collect water droplets and soot particles from the exhaust.

Keith

Hi Keith, I was visiting my eldest son in London this weekend and he’s been interested in aerodynamics for a while, so we were chatting away about it and he mentioned there is a couple of pieces of software available to mimic a wind tunnel. After I got home from London last night he had a play with some software and came up with the following picture attached. He does stress to me though that he does not know what he’s really doing and said he manually traced out a 2d outline of a TR6, loaded it up in a cad software and generated a CFD of the flow air at 25m/s (56mph) he also said a 3D one would be possible if he had a CAD model of a TR6.

He’s a coder for Apple so not what he usually does.

Just for fun but does give a good idea of what’s going on.

EFED89EE-DAFA-408B-99F3-876B1F86BA1C.jpeg

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Solidworks, the CAD programme, has a 3D aero add-on.

Kevo junior has imaged well the vortex there is behind most cars.       The ideal with least drag, is a teardrop shape, with a long pointed tail, but it was Herr Doktor Professor Kamm who showed that cutting that off, leaving a flat 'transom' back end did not make drag significantly worse, as the vortex is so powerful that it approximates to a solid body, and th rest of the flow goes over it.    The TR6 back side is just such a transom, or Kamm tail.

This menas that anything in the vortex recirculates, and this can include exhaust fumes.    But the vortex on one side rotates in the opposite direction to the other side, so that exatraction tends to be from the centre.  It may be that gases from an exhaust pipe in the centre, not to the side, will be removed more quickly, and not access the boot.

image.thumb.png.485fb656d9fdd63ab6ffc2ed260e3cc2.png

JOhn

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37 minutes ago, john.r.davies said:

Solidworks, the CAD programme, has a 3D aero add-on.

Kevo junior has imaged well the vortex there is behind most cars.       The ideal with least drag, is a teardrop shape, with a long pointed tail, but it was Herr Doktor Professor Kamm who showed that cutting that off, leaving a flat 'transom' back end did not make drag significantly worse, as the vortex is so powerful that it approximates to a solid body, and th rest of the flow goes over it.    The TR6 back side is just such a transom, or Kamm tail.

This menas that anything in the vortex recirculates, and this can include exhaust fumes.    But the vortex on one side rotates in the opposite direction to the other side, so that exatraction tends to be from the centre.  It may be that gases from an exhaust pipe in the centre, not to the side, will be removed more quickly, and not access the boot.

image.thumb.png.485fb656d9fdd63ab6ffc2ed260e3cc2.png

JOhn

Thanks John very interesting, I spoke with my son Tom this morning and he’s working on a 3D version already. He absolutely loves stuff like this.

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45 minutes ago, john.r.davies said:

Please post when he's finished!

Will do John.

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On 1/10/2020 at 10:42 PM, Markus said:

Hello Phil H 4.

Can you advise where you purchased your wind break?

I’m interested for two reasons.  Possible fuel smell elimination as well as hopefully, less hair ruffling.  Not mine.

Cheers!

Hi Markus,

The mesh wind deflector came from Just Roadsters Ltd. www.justroadster.com.

I made some alterations to the brackets to raise a couple of inches which made a significant improvement.

Edited by Phil H 4
mis spelling

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Very interesting airflow simulations in the earlier posts above. I was once involved in computational fluid dynamics (CFD) looking at air movement in clean rooms. The comment that centrally placed exhaust pipes may result in better extraction of exhaust fumes is particularly interesting. When I bought my 4A it had a crossbox with the pipe exiting near the nearside over-rider. I often had to clean the soot off this. I then changed to twin pipes that exit more towards the centre line of the car. I still had some issues until I extended the tail pipes beyond the bumper. They are now 13 inches apart (centre to centre) and extend 4 inches beyond the bumper. Sounds a lot but looks ok. The extension pipes also to some extent direct the gases down towards the airflow under the car shown in Kev's simulation. This would appear to be better than the fashionable open ended pipes seen on many TR's

The first simulation by Kev also shows the vortex behind the windscreen when the top of the car is down. This explains why, when driving through drizzly rain with the top down, the inside of the windscreen gets covered in rain as well as the outside.

Fascinating stuff - thanks to the tech guys

Keith

p.s. this would make a really good article for TRAction!

Edited by keith1948
added more info

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23 hours ago, Kevo_6 said:

Hi Michael, I’ve have my seal fitted with join at the centre rear closest to the petrol cap. As I see it it’s further away from the exhaust. Not sure if this is what Neal (NTC) means.

Hi Kev

There is more to it than that, You only have to see how they was fitted when new.

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5 minutes ago, ntc said:

Hi Kev

There is more to it than that, You only have to see how they was fitted when new.

Hi Neal, hope you are all well.

 You’ve now made me think that maybe the rubbers have a deeper slot and maybe if I put a suitable size cord in first and then fit the rubber this would raise the seal, which would compress the seal better and possibly glue the join.

Ahh that might make the boot difficult to shut.

Am I on the right track? :rolleyes:

 

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