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Rob Y

Exhaust fumes smell in boot - solved

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Like many people I have been struggling with exhaust smells in the boot of my TR6 - initially I thought it was fuel and made changes to the fuel pump, pipes etc as described on this forum in many places. After this though the smell was still there and it meant wrapping any luggage in bin liners to prevent the smell permeating everything. Not a good look when going into a nice hotel!

Lots of suggestions about boot seals etc, so I adjusted the boot lid to get a good seal (tested with Vaseline on the seal) but the problem persisted.

I was struggling to understand how the exhaust fumes could get into the boot, even if there was a small hole somewhere, but after a relatively long trip with the roof down and a jacket tucked under the hood behind the back seats, I noticed the jacket had the same smell. This could not have come from the air just coming into the car because the roof was down as the jacket was completely tucked away under the folded down hood and hood cover.

I developed a theory that low pressure is generated in the cockpit of the car when driving with the roof down that sucks air and exhaust fumes from the back of the car through the boot into the car itself - this would explain why with very small holes in the boot seals that such a strong smell of exhaust can get into the boot.

So, to test/cure this I fitted a polythene sheet sealed with silicon sealer behind the rear cockpit liner to effectively seal the boot from the cockpit of the car. I did also change the rear light seals at the same time as I had bought these before developing this theory - this may have helped but I don't think this was the main reason for the cure.

Since then there has been no smell in either the boot or behind the rear seats on any items left there. I need to test this on a really good length drive but so far I am extremely pleased with the result. I think sealing the inside of the cockpit from the boot is the real solution to this problem.

 

I know this topic has been debated and suffered by many for a long time so I hope others get the same results I have from this very simple fix.

 

Rob

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I fitted a sealed steel bulkhead in front of the tank when I had things apart to renew all of the rubber fuel lines with Gates Barricade a year or so ago, at the same time I had the MU recalibrated and the injectors rebuilt.

 

When this work was completed the petrol smells, which I had considered part and parcel of TR6 ownership, totally disappeared.

 

However the real reason I fitted the steel bulkhead was to avoid petrol running around my feet in the event of a split tank- containing the fumes was a side effect.

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Sounds like it has worked for both of us - hopefully I am on to something here and it works for many others - steel or polythene - sealing the cockpit from the boot sounds like a good idea regarding at least stopping the fumes in the boot!

 

Rob

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Good info and theory Rob, thanks.

Waldi

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Also fitted a rear firewall between the cockpit and tank. Didn't solve the issue for, but sealing the rear light gaskets work fabulously.

Guess it may be a combination of affects.

Tim

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Very interesting thread and not too far removed from my posting earlier this year regarding my smell of fuel resolved by refitting hoses, sender unit joint and an opportunity to fit a fire wall.

 

I do however still have an exhaust smell that builds up although no where near as bad as the fuel problem. I have a twin sports exhaust with parallel outlets to help reduce efflux. While fitting led tail/brake lights the other day. I noticed how dirty the internals of the light clusters were when looking in from the boot. I had replaced all the lenses some years ago but cannot really remember how good or bad the seals were. There's is clearly evidence here of exhaust gas intrusion!

 

Another job on the list to review and check, clean up and refit.

 

Thanks Trevor

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Hi there, this was mine I fitted in the spring this year, an opportunity arose when I had the fuel tank out. Its not pretty, its aluminium (forget gauge, I'll research that and update tomorrow) and fitted in with a silicone sealant, and gaffa taped for good measure. I had the section cut to size, but I had to modify further to fit over the raised bodywork for the rear axle.

 

I'm sure there are better examples out there, but it fitted reasonably well, and would at least restrict a catastrophic fuel leak in the forward direction.

 

Best Regards Trevor

post-10007-0-52869800-1533680398_thumb.jpg

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Sorry here's a wider perspective.

post-10007-0-50242100-1533680863_thumb.jpg

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My version was in 3 pieces for ease of fitting.

http://72tr6.blogspot.com/2017/05/the-big-reassembly.html?m=1

Cheers

Tim

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Hi Tim, good idea, mine was a tricky fitting, not been a metal fabricator, a touch of brute force and ignorance made it fit!

 

Regards Trevor

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Also fitted a rear firewall between the cockpit and tank. Didn't solve the issue for, but sealing the rear light gaskets work fabulously.

Guess it may be a combination of affects.

Tim

This is a really interesting discussion, I wondering if I should try to seal my rear lights too. Please can you tell me more about how you did this please?

 

The fumes in the cabin are beginning to annoy me!

 

best wishes to all

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My previous owner had used a silicon sealer on the rubber gasket but still smelled. Biggest improvement I have made is replacing the sender gasket on top of the tank , the filler neck gasket and the grommet around the filler cap. Don’t over adjust the boot lid catch to make the list sit lower.

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This is a really interesting discussion, I wondering if I should try to seal my rear lights too. Please can you tell me more about how you did this please?

 

The fumes in the cabin are beginning to annoy me!

 

best wishes to all

Non setting windscreen sealer will help, like this https://www.ebay.co.uk/itm/Windscreen-Sealer-Window-Sealant-Black-310ml-car-van/371592868637?epid=1789195900&hash=item5684a9331d:g:YPoAAOSw~y9ZAeTG

Stuart.

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What gauge aluminium should be used for the rear firewall?

 

Thanks

Sean

18SWG or 1.2mm is what we use.

Stuart.

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I'm going to source 1.2mm aluminium sheet from an online stockist a make a firewall myself, is it better to fit between the fuel tank and the support struts or between the cockpit and support struts?

I'm hoping it's the latter, that way I don't need to remove the tank.

 

Richard.

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I did the latter

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Yes, fitting the alloy sheet immediately underneath the rear of cockpit fibreboard is the best position. You can use the fibreboard to draw around and as Tim says making the firewall in 3 pieces makes it a lot easier.

Place around the cockpit on top of intumescent sealer ( it swells when exposed to heat) or Indasa windscreen sealer ( the idea is to buy you a minute or so of grace to allow egress from a burning car). Then pop rivet every 25mm into the cockpit top frame and down the vertical struts, then attach the 2 small tabs which go over the rear wheel arches and rivet to the vertical struts and inner wing, a few small brackets help the job and seal underneath as you go.

If you have a 4-6 with Surrey backlight or hardtop you can loosen off the securing nuts and bolts and by jiggling the top get the alloy sheet underneth the overhanging edge.

 

Mick Richards

Edited by Motorsport Mickey

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I found a very simple answer. Just set the fuel system up correctly and it does not run rich. Hence no fumes and no smell. If you have a CO values from 5 or 6+ then don't expect anything else. Of course good seals help.

The garages nowdays set the cars up for about 5% + to be on the safe side, no matter what it costs the customer.

 

In 1972 in California the rules were 0:5% to 2.5% maximum. Triumph achieved these values and the cars ran with inleaded petrol. Why now over 40 years later are we running with a much higher CO value? In fact I manage to get my PI down to 0.8% and it ran. Not recommended because you will soon burn something out. With about 2.50 % it ran for many years with a high performance and using todays petrol.

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Totally agree Peter..

When I had PI on the car I was able tune the PI to run well much leaner using a AFR meter. The only thing I had to be aware of was if I ran too lean I got a transient misfire on snap throttle (as the PI doesn't have an throttle enrichment device)..

Cheers

Tim

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I have owned my TR6 for over 20 years and it has given me much pleasure. When I first bought the car in 1998, it had a number of additions switches fitted in front of the gear stick.  (See picture). One of which said “interior fan” which turns on a small fan to the right of passenger in the foot well. It never seemed to make much sense to me, however I wondering if the effect of the negative pressure in the cabin with the top down is neutralised when it’s turned on. I have been trailing this theory in the last few days and indeed it does seem to help.

I’m sure there are expert on this group who may have opinions, but thought I would share it. As a practical alternative if indeed it works, why not always have the heater fan on low to reduce the Fumes in the cabin issue?

 

i may of course be talking nonsense, but seemed worth a mention. 

A279DC24-AE3C-4C28-902A-89ED92F7CAA1.jpeg

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Hi

so I recently put a new alu' fuel tank in.  can I do this from inside the cabin so I don't have to re-do the work?

Rich

 

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