Petrol Breathing - Ken Inds Design - Club Lotus

[terryp]

Robbie
I've just bought some 13mm ID fuel pipe, a little more expensive than standard but I thought very worthwhile. For the small pipe 6mm ID Fuel pipe OD 9mm hopefully will be able to be fed through the old pipe round the headlining bit. I don;t think I would be able to afford the pipe in the thread. The pipe I have bought must be better than the old pipe!

Thanks
Terry

[Robbie693]

Hi Terry,

Yes the braided stuff does look expensive. I was thinking the same as you about feeding the smaller pipe through the existing ones but haven't had a go yet.

I'd be really interested to hear how you get on - please let us know your results, especially if you banish the smells!

Cheers

Robbie

[Higs]

Terry, Robbie

Do you know that the old piping is leaking? i.e. do you have patrol smells within the car?

If all you are trying to do is stop petrol smells in the garage then why go to the hassle of threading smaller pipe through the old pipe (this is probably not easy). To reduce garage smells, you simply need to reduce the size of the breather to the wheel arches i.e. but a bung in it and drill a small hole (or any of a number of similar ways).

Then all you need is to solve the tank filling problem. This is done by using the filler neck fitting and then running the pipe from there to a "T" in the nearest, existing, breather tube.

This has to be easier!

You only need to thread new, smaller, tubes if the existing tubes are so perished that they leak.

Richard

[Robbie693]

Hi Richard,

In my case it's the smell inside the car and boot. I've replaced the filler hose and sealed the areas where the breathers exit the car so I'm left with the breather tubes themselves looking like they need attention (hence my conversation with Gerry a while ago), it's just low on the job list at the moment. The breather hoses look fine actually but I'm not sure what they are made of and am assuming that they are not up to the job of containing the fumes.

Filling has never been a problem, just not quite as fast as a modern and the spillage on the wing problem I sorted a few years ago.

What's mostly putting me off tackling the job is removing the rear screen as, at the moment it doesn't leak water in and the heated screen works so I'm loath to remove it for fear of creating more problems, as these things often happen when I do jobs on the car! This is why Terry's idea of putting 'inner' tubes in appeals. The only problem i can see is if the breather diameter is critical(?).

Cheers

Robbie

[Higs]

Robbie

The diameter of the small tubes can be as small as you like - all they do is allow relatively slow expansion / contraction of the petrol/air in the tank or to replace fuel with air when driving (so, max flow rate of air is, say, 2 gallons per hour - not much). Therefore go for small to reduce evaporation loses and to make it easier to thread through the old pipe.

The size of the pipe from your filler neck to the new junction you are putting in and then onto either side of the fuel tank is critical for the speed of filling. Keep this at least the size of the current piping.

It would be worth checking the padding under the tank as well - this is a good indicator of leaks elsewhere (tank or fuel pipe etc).

Richard

[Robbie693]

Thanks Richard,

I thought they must be that size for a reason, just hadn't made the connection that it's the breathing while filling that's the critical bit

The tank looks fine, almost new in appearance and the felt underneath is dry and doesn't smell so I think it's ok.

Cheers

Robbie

[kstrutt11]

On mine I fitted a small aero style cap (no more leaks) which has a shorter filer neck, I then used a off the shelf elbow as a new hose to the tank, in the new longer hose I added a 1/2" BSP domestic brass water tank fitting with a length of 15mm copper pipe on the outside to which I soldered a 10mm reducer, 10mm t and 2 lengths of 10mm pipe the two breathers were then connected to these and a very small bore breather pipe added (length of copper brake pipe).

It has been like this for several years now with no leaks, smells or other problems.


kevin

[terryp]

Hi Terry,

Yes the braided stuff does look expensive. I was thinking the same as you about feeding the smaller pipe through the existing ones but haven't had a go yet.

I'd be really interested to hear how you get on - please let us know your results, especially if you banish the smells!

Cheers

Robbie

Robbie
Its done! Albeit with the aid of some washing up liquid!
I squeezed RTV in the ends of the old hose and sealed the small hose in the big hose so I don't get any smells...

Good Luck
Terry

[alan.barker]

Hi Terry,
be very careful using RTV, because it doesn't like petrol. You can end up with some little pieces of it in the petrol tank which will be sucked into the outlet of the tank and block the supply to the engine. i once used RTV on the gasket for the tank sender on my Elan Sprint and it very nicely blocked the supply to the engine. Luckily i had fitted a filter just after the outlet on the tank, so i could remove the blockage trapped in the filter
Alan.B

[Robbie693]

Robbie
Its done! Albeit with the aid of some washing up liquid!
I squeezed RTV in the ends of the old hose and sealed the small hose in the big hose so I don't get any smells...

Good Luck
Terry

Excellent - Thanks for letting me know Terry.

Glad you don't have any smells!

Cheers

Robbie

[cdraper]

i solved the petrol smell - tank filling problem by connecting one pipe to the filler neck as illistrated and fitting a much shorter pipe the other side - tucked up in the boot above the tank with a one way valve. ie air can get into the tank but not out. Never had any problems, now a fast filler, no smell, but the car would not longer meet the US roll over legislation which accounts for the design in the first place. Now no longer uses a litre plus amonth when parked!

[terryp]

Hi Terry,
be very careful using RTV, because it doesn't like petrol. You can end up with some little pieces of it in the petrol tank which will be sucked into the outlet of the tank and block the supply to the engine. i once used RTV on the gasket for the tank sender on my Elan Sprint and it very nicely blocked the supply to the engine. Luckily i had fitted a filter just after the outlet on the tank, so i could remove the blockage trapped in the filter
Alan.B

Alan
It should be OK, I used it on the outside of the small pipe within the large pipe, on the ends of the disused large pipe and to seal the take off to the petrol cap but that was a flat bulging outwards, rather than a bulging inwards.
Its not for use when the silicone is immersed in petrol but for a breather and the occasional splash it should be OK.

Terry