Lotus Elan

Securing fuel tank breather pipe to roof.

PostPost by: Bigbaldybloke » Wed Jan 24, 2018 8:05 pm

Hi all, I?m about to start re-trimming the inside of my early Plus 2 but need to install the fuel tank breather lines before I get started. I?m going for the standard routing up over the roof behind the head lining. My question is how or what have people used to hold these pipes in place and secure them to the roof. It looks like there may have been some sort of adhesive or tape used originally by the marks on the inside of the roof, but what is the best option now?
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PostPost by: jono » Thu Jan 25, 2018 10:47 am

...what about some self adhesive cable tie pads and then cable ties?
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PostPost by: alan.barker » Thu Jan 25, 2018 11:09 am

If it was me i would use tape to hold them in place. Then use some fibre glass tissue to hold them in place permanant. If you want to do the breather mod you can also slide inside one of the big vent tubes a small plastic tube up and over and down the other side. It's easier to thread the small tube inside the large now.
I suggest you also do the "Mazda MX5 non return " mod to stop fuel coming out the filler when you take corners.
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PostPost by: gus » Thu Jan 25, 2018 1:12 pm

No no no no no!!!

Just don't

Really, do not run the tubes over the headliner.

run one hose over from the filler side over to the other side, directly on top of the tank
install a 'T' to connect to a short hose that connects to the other tank vent, and third long hose that runs forward and up, then over the C pillar vent and down and through the hole in the floor.

The entire system is now accessible, invisible, and repairable without removing the headliner

you just want to make sure everything stays 'up' so it does not fill with fuel

this also eliminates fuel smell in the garage
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PostPost by: JonB » Thu Jan 25, 2018 1:31 pm

Something like this, I believe.

%2B2 Petrol Tank Mod.pdf
(942.32 KiB) Downloaded 344 times


..along with the MX5 non return valve. Let us know how you get on!
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PostPost by: alan.barker » Thu Jan 25, 2018 2:24 pm

+1 Jon you said it all, the best way to go
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PostPost by: RichC » Thu Jan 25, 2018 5:19 pm

just to say when i redid my shell i kept the pipes in original site and put a little fibreglass resin tabs up to keep them in place and out of the way of the new headlining in the middle of the roof.. you'll need the pipes to be held in place whilst it sets .... the b post interior panels were able to hold up the sides . i got new headlining from aldridge trimming . It was all a complete pain in the arse to do .... especially getting the old hardened pipes thru the fibreglass hole grommets inboard of the wheels . Being trouble free for 50years i was thinking i'd not need to touch them again and never thought to replace with anything else
never did have any fuel smell coming from the rear . still don't . |Mind you it's all pretty flat round here and i've never needed to park on a steep slope with a full tank.
got me thinking, what is the source of +2 petrol smell usually? olive leaking on the old nylon fuel line in to pump?
carbs?
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PostPost by: vxah » Thu Jan 25, 2018 5:26 pm

In hindsight though...... I would run a small diameter vent tube over the roof so as to use a non vented cap and not have an issue with getting a vent high enough? As an afterthought I ran the small tube up inside the interior vent "ear" as high as I could then back through the boot floor, a 1mm restrictor fitted in the pipe lets the tank breath and no stink in the garage!
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PostPost by: jono » Thu Jan 25, 2018 5:31 pm

what I did.
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p1040065-copy.jpg and
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PostPost by: gus » Thu Jan 25, 2018 7:08 pm

With a sealed cap, which I would think all +2s should have, and a good gasket in that cap[which few +2s have] no fuel comes out of the tank, pretty much ever.

jonos pic looks like no vent, and unless it is a vapor recovery tank[Fed 71 on] that would be wrong

The club lotus method is fine, although my car does not have any vent in the filler neck, and there is no reason to bother going over the roof, just loop it over the c pillar vent
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PostPost by: Bigbaldybloke » Thu Jan 25, 2018 8:01 pm

Lots to consider there. I like the idea of connecting the vents into the filler neck to cope with the fast venting when filling, but how have people connected to the filler neck? I assume some sort of threaded Union brazed of welded into the neck that can then have a connection screwed into it? If it stuck out the side much you would have trouble getting the grommet on the filler neck and then inserting that into the hole in the wing. As for the venting when not filling, the use of a smaller bore line makes sense and I?ve ordered myself one of the fancy venting valves from Newton?s
https://www.newton-equipment.com/In-Lin ... master.pdf
to try in that line. As suggested maybe just taking this line up to the top of the ?c? pillar then back down again and out through the original grommet hole and into the wheel arch sounds better than running it across the roof. Only doubts I have are if this doesn?t work I?ve got to remove my rear window and head lining again to put the original design pipes in!
Hmmmm, how brave and adventurous am I feeling?
All depends on getting a good connection method into the filler neck, if I can?t do that the rest is a no go. I guess this line must be as high up on the filler neck as possible as once the fuel covers this you can?t fill the tank any higher with this type of vent scheme.
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PostPost by: Bigbaldybloke » Thu Jan 25, 2018 8:18 pm

Ive been studying this a bit more and thinking about solutions.
Thought one, petrol station forecourts are nowadays almost always level or very nearly so, and if not you could always position the car so that the filler cap was on the higher side.
This leads to my ideas. Just connect the vent on the filler side of the tank to the filler neck with a big bore connection.
Connect a small line from the other tank vent up the c pillar with a vent valve in it and then back down the c pillar through into the wheel arch area and finish it down below the bottom of the tank level.
When filling it vents through one line and you can fill the tank until the vent in the filler neck is covered.
When the filler cap is closed it can draw in air through the small line and the vent valve, but unless there is excess tank pressure fumes will not come out the small vent line as the valve prevents it. If the car is in the sun and gets hot the vent valve will relieve over pressure. If the worst happens and the car ends up upside down, the cap is sealed and the end of the small vent line will be above the tank so should not spill any fuel.

Thoughts?
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PostPost by: The Veg » Fri Jan 26, 2018 12:51 am

FWIW, what I did is similar to much of the above. First I connected the vent spigot near the filler to the filler via a barb fitting screwed into a threaded bung that was brazed into the filler neck as near the top as possible. Then I connected a hose to the vent spigot on the other side and ran it across the tank, then up the C-pillar and down to the floor as Gus suggests. Down where the hose comes out the bottom of the car, instead of just shoving it out the hole I riveted a plate over the hole, and the plate has a more precisely-sized hole in it in which I affixed a sintered-metal pneumatic silencer. This should allow free exchange of pressure while blocking anything from getting in. The hose I used is Tygon, which is compatible with petroleum, very light weight, and should remain pliable much longer than the original PVC.

I did also install the MX-5 valve in the top of the elbow, which is a new elbow made of reinforced silicone as the original had hardened to the point that I feared it being brittle.

I think too that I saw a new filler cap gasket amongst the various bits the seller included.

Time will tell how well all this works, as the car is not yet back on the road.
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PostPost by: jono » Fri Jan 26, 2018 8:13 am

I should add that my photo was a work in progress.

My final version introduced an 8mm vent pipe which I looped over the rear window and down the other side then it pops out under the car with a copper tip.

Been working great for 15k miles - no petrol smell in the car
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PostPost by: TeeJay » Fri Jan 26, 2018 10:48 am

My solution was similar to Jono?s, (and Club Lotus) with 1 hose going from LH side up along roof and down RH side out into original hole in wheel arch.

The fuel vent pipe connection screws into the fuel filler and is removable. This is necessary, so the fuel filler can be fitted and removed.

fuel-tank-new-breather-system.jpg and


fuel-filler-vent.jpg and
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