Fuel leak - between tank and tap

[snodpete]

I have an annoying (and I guess potentially explosive..!) small leak of fuel on the Spada. Have had the tank off numerous times, renewed the o-ring, added carb-gasket goo, also some silicone on top of that... Still there is a small leak.

Small stain on garage floor 2-3cm in diameter, and general 'dampness' around tap fitting. It's hard to isolate cause exactly but it seems to be from the join to tank.

Any ideas? Any suggestions for a superior sealant impervious to fuel? Any sources of better Spada fuel taps (current one has a screw blocking what I assume is a small bypass tube or something - it just drains to the collector sump under tap - when screw is removed leak is worse)?

Thanks in anticipation for your expert advice.

[Skunk]

I fixed mine by cutting a 'gasket' out of inner tube. Has worked well with the original 'O' ring gasket left in place.

[snodpete]

Cheers for that idea, Skunk - looks like a little weekend project then

[MSTRS]

If the leak is between the tap body and the tank, try Hylomar. It is THE #1 gasket 'goo'. Apply sparingly to both surfaces (clean and dry), wait for it to semi-set then bolt together. That stuff seals dodgy carb bowls.

[snodpete]

Thanks for that info about Hylomar MSTRS, having a go at the 'rubber tube' gasket today. Will post with results.

EDIT: Worse than before! Only had mountain bike tube but... Back to the workbench with that job :angry:

[MSTRS]

No wonder. Inner tube rubber is NOT fuel resistant. Do not use it.

[Skunk]

No wonder. Inner tube rubber is NOT fuel resistant. Do not use it.
That's what I thought but mine has sealed. Mine was supposed to be a temp fix to test the bike but it's still sealed three months later.

Go with MSTRS suggestion.

[FLYMO]

u can get fuel resistant gasket rubber at most acessory shops
other than that make sure the surface of the tap is flat
u may have to face the alloy off to get the warp out of it

[geoffm]

Second Hylomar - it has worked for me in the past.
A lot of RTV silicones aren't petrol proof - hylomar is.
geoff

[LBD]

If you renewed the o-ring with a factory original and it still leaks, remove the valve and have a very good inspection of the face on the tank where the o-ring sits, possibly with a mag glass, and look for damage or cracks. Inspect o-ring for perishing.

If O ring is not original, ensure o-ring is correct size.

Suggest take oil o-ring to Cat dealer and ask for a similar petrol resistant o-ring. (the cat range are about as good as you can get) If all okay assemble with light smeer of grease on thread and o-ring. do not over tighten.

[CookMySock]

I go along with LBDs suggestions. It's easy to plaster all sorts of goo on something that is assembled incorrectly, and it still leaks!

Try a new O ring, or make a cork gasket if there is room. The important thing with O rings and gaskets, is to assemble them totally clean and dry. If you don't, they slide out of place when you tighten then. Also, adding gasket goo just makes said sliding much more easily done, so basically it doesn't work, so scrape the shit off the mounting surfaces, clean with petrol, clean with meths, allow to completely dry, double check for flatness and cleanliness, and carefully reassemble. Snug it down, don't tighten it heaps, or you will deform it, and it will leak!

Also check that your fuel cap is venting correctly, or else when the full fuel tank is under pressure it will hydraulic fuel out the weakest point. Usually happens when you park it in the sun.

Steve

[Filmer]

Cheers for the advice mate, my carb bowls were leaking, used Hylomar and now not a drop of fuel on the ground under the bike, i picked some up from repco, highly recommend for an easy fix. :2thumbsup

If the leak is between the tap body and the tank, try Hylomar. It is THE #1 gasket 'goo'. Apply sparingly to both surfaces (clean and dry), wait for it to semi-set then bolt together. That stuff seals dodgy carb bowls.

[MSTRS]

Good to hear. I've found that Hylomar is more or less the only gasket goo you will ever need. I don't know why people fuck around with anything else.

[snodpete]

Couldn't get any satisfaction out of Repco in Christchurch (2 branches) or Greymouth, but finally sourced some Hylomar from an engineering supplies place in Chch (Google is your friend...). Have disassembled the Spada fuel tap - AGAIN - and followed all advice on here re cleaning surfaces, checking for flatness etc.

After my last efforts the body of the tap was leaking, around the vacuum-magic-pixie bit that seems to be more trouble than it is worth! Have stripped, cleaned and reassembled that with Hylo. Will report back with results.

Attached pic shows the thing in bits, for those who like bits.


EDIT #1 - What appeared to be a leak between tank and tap *may* have been dodgy seals on the tap face-plate. I concentrated earlier fixit attempts on the vacuum valve side, we'll see.

EDIT #2 - Sho' nuff - Stripped and cleaned tap; dismantled the tap side properly for the first time, removing gunk from previous rusty tank, reassembled whole unit with judiciously applied Hylomar to all joins in the tap body. Cleaned faces of tap and tank then replaced single O-ring with slightly fatter one and NO sealant whatever. Snugged up all screws and mounting bolts and hoped. Checked tank on bench when half full, seemed OK. Rode to petrol station, filled her up and rode to Mokihinui, with a quick blast up Millerton Hill on the way back. So far so good! I want everything to be sorted for my 6F in a week. Thanks again for all the advice and tips on here, oh wise ones.