Petrol smell

[Magoo]

Hi all

I have recently purchased a TR4A with a slightly tuned engine(Stage 3 head, sprint cam etc)

I am running on twin weber 45DCOE's. The car has an electric pump in the boot, regulator in the engine compartment and an emergency cut off switch.

There is a smell of petrol that I cannot find. It is worse on the passengers side and possibly worse starting off after the car has been sitting.

I have checked the fuel lines and connections but cannot find anything. Was thinking of changing the filter for a start. It is clear plastic and looks quite flimsy.

Could it be petrol evaporating from the carbs? Should I fit a heat shield to the carbs. If so best source for one? Could it be that the carbs just need a good cleaning?

Guidance appreciated

Thanks

[stuart]

You could try taking the boot board out and having a look at the hose on the filler kneck and around the tank where it sits over the axle and around the straps as the 4/4a tanks are known to rot from the outside inwards where the mounting padding is located. It only takes a small amount of fuel to create a strong smell.

Stuart.

[Horse]

Whilst you have the "cardboard" baffle out to gain access to the fuel tank, have a look at the fuel gauge sender. These also leak from the seal when the seal is getting old and can be the source of fumes, but with this, the tank and the filler, the smell is usually most noticeable in the boot.

 

No other ideas I'm afraid, other than to suggest you go round every bit that has fuel in it or passing through it, and particularly unions, wiping it with a tissue and inspecting the tissue regularly. A tissue will find moisture if there is any even if a joint feels dry.

[robgeev]

For what it's worth, my 6 has Webbers, no visible leaks, but the occasional petrol stink is there, I put it down to evaporation in the carbs.

I would be attention to the places mentioned above, the sender seal would be my favourite.

What sort of state of tune is yours, such that it needs 45's? Must be quite entertaining?

 

Rob.

[Magoo]

For what it's worth, my 6 has Webbers, no visible leaks, but the occasional petrol stink is there, I put it down to evaporation in the carbs.

I would be attention to the places mentioned above, the sender seal would be my favourite.

What sort of state of tune is yours, such that it needs 45's? Must be quite entertaining?

 

Rob.

 

Thanks for suggestions chaps.

So far I have had the webbers reset, they were badly out, and I fitted heat shields to the carbs. The back board was removed and I checked the tank, it seems new? The sender gasget was ok, could not get any more tightening of the nuts.

the man who set the carbs found the tank breather going out on the drivers side rear wheel arch so he changed it to go out through the back end under the bumper. He also said he got the occasional 'blast' of a smell but could not trace it.

Smell still there hood up or down. Goes away when I open the air vent.

 

Will now recheck all joints again, think I will replace the filter, looks cheap and plastic.

 

Bob asked about the car. I bought it end of last year so just starting to use it now. Rebuilt about 3 or 4 years ago. Reground crank, balanced tuftrided. New balanced pistons. Sprint camshaft, triumphtune stage 3 head. Weber DCOE 45's, triumphtune inlet manifolds. Suspension improvements. Racetorations ss race manifold. Lots of other little improvements. Certainly goes well, lots of power even at speed.

 

If only I could trace the fumes!!

[North London Mike]

Hi all

I have recently purchased a TR4A with a slightly tuned engine(Stage 3 head, sprint cam etc)

I am running on twin weber 45DCOE's. The car has an electric pump in the boot, regulator in the engine compartment and an emergency cut off switch.

There is a smell of petrol that I cannot find. It is worse on the passengers side and possibly worse starting off after the car has been sitting.

I have checked the fuel lines and connections but cannot find anything. Was thinking of changing the filter for a start. It is clear plastic and looks quite flimsy.

Could it be petrol evaporating from the carbs? Should I fit a heat shield to the carbs. If so best source for one? Could it be that the carbs just need a good cleaning?

Guidance appreciated

Thanks

 

Hi John

Have to agree with the guys on this one. If the smell is in the boot then it's likely to be the sender unit seal as its a big hole! See my previous post, I sealed mine and reduced the smell by 80%, other joints may contribute but if there are no leaks then it points to the sender seal. However, if it smells in the engine bay then its either the breather blowing back fumes into the engine bay and then into the heater intake or manifolds leaks.

 

It points to fumes not fluids

 

Petrol leaks with the engine (& pump) running would show. Fumes are much more insidious. Check gaskets, manifold nut torque, blocked breather etc. However, as the engine is 'hot' it will need more breathing, if it hasn't been fitted to the block then its trying to get out (any oil leaks ?)

or if badly done, they're leaking...........stronger smell as you set off points to a build up of fumes not petrol (which would evaporate)

 

Hope some of this helps

[gwr]

Check also the seals on the large diameter rubber tube between the filler cap and the top of the petrol tank. There ought to be a jubilee or radiator hose clip top and bottom of this pipe. If the smell of petrol is pronounced after filling up, then it could be that one of these clips is loose or missing.

[Magoo]

Check also the seals on the large diameter rubber tube between the filler cap and the top of the petrol tank. There ought to be a jubilee or radiator hose clip top and bottom of this pipe. If the smell of petrol is pronounced after filling up, then it could be that one of these clips is loose or missing.

 

Hi all again. All hoses and clips in place and tight, no smell from that area.

I think I now have narrowed it down to the breather. there is a strong petrol smell from the end of the breather pipe.

No smell from tank area.

I have traced and exposed the breather. A copper pipe comes out through top of the tank and goes through boot floor and stops in the rear passengers wheel arch area. The end of the pipe is partially nipped. There is no doubt that the smell is stronger in the passengers side.

How to get rid of it? When I had someone work on the car a few weeks ago he noticed the smell. He put a length of hose over the pipe end and led it back to the back bumper. No improvement! However when I exposed the breather/hose joint today under the passengers wheel area it had no clip on it and a loosish joint!

Question. 1) should I open out the nipped end of the copper pipe? Or is that likely to let more fumes out? Should I close it up and just leave a pin hole(to equalise pressure build up)

2)I can seal the rubber/copper joint and make all the fumes go out through the pipe at the back. Do you think there might be a suction effect and pull out more fumes to be recirculated back into the car?

3) where is the breather meant to come out? I have looked at the Moss books I have and the TR Register CD but I cannot tell

As always advice appreciated.

John

[MikeF]

Hi on changing my '4 tank over I came across this, the tube just dangled down into the rear wheel well. It wasn't nipped anywhere.

The fitting of the breather pipe to tank on mine was broken and had been epoxied over. I was able to re-solder it (as I have access to the highly active stainless steel flux necessary to work on the fitting. Way over Bakers Fluid . Don't ask me why Triumph used an expensive SS fitting, probably because it was handy!) It might be worth using some fuel tank sealant over that area in case you have pinholes or cracks in the original joint, Likely in view of the difficulty of soldering.

 

Another thought is that I believe on later cars (TRs and Spitfires) the breather arrangement was incorporated into the main filler area. You might want to look at that and so do away with the pipe altogether.

 

 

Mike

[Magoo]

Hi on changing my '4 tank over I came across this, the tube just dangled down into the rear wheel well. It wasn't nipped anywhere.

The fitting of the breather pipe to tank on mine was broken and had been epoxied over. I was able to re-solder it (as I have access to the highly active stainless steel flux necessary to work on the fitting. Way over Bakers Fluid . Don't ask me why Triumph used an expensive SS fitting, probably because it was handy!) It might be worth using some fuel tank sealant over that area in case you have pinholes or cracks in the original joint, Likely in view of the difficulty of soldering.

 

Another thought is that I believe on later cars (TRs and Spitfires) the breather arrangement was incorporated into the main filler area. You might want to look at that and so do away with the pipe altogether.

Mike

 

Thanks Mike.

I looked at other Forums and the TR6 one has a lot of interesting posts on the subject.

Seems that UK TRs(and tanks) should have only a breather in the cap as you suggested. USA models had a sealed cap and a breather tube which went to the front of the car to a carbon filter.

Some replacement caps apparently can be USA types leading to problems of pressure or suction. Similarly replacement tanks might have a breather or a sealed hole.

Anyway, I tested the cap and indeed it has a breather(in and out). With this knowledge I sealed the breather which came out under the wheel arch.

Took the car for a long run today and no problems with smell.

Great. Thanks to all for suggestions and advice.

John