Fuel tank leaking at hinge!!

[Phatty]

The S4 has spent the last year up the car port due to lack of space in the garage. Now it is garaged I've noticed a strong petrol smell whenever opening the door.

I have also noticed a brown petrol smelling residue on the left hand side of the frame directly under the lowest point of the tank.

Just lifted the tank and gave it a good wipe around ten waited to see if it got wet again. Within minutes streaks of fuel starting to appear from the hinge.

What would be the recommended treatment here? Run a bead of petrol resistant sealant around it? Remove and reweld hinge? Or chuck a tank sealing kit inside?

Is this a common problem? No signs of any rusting or perforation from what I can see.

[Capo]

Its not unknown lifting the a full tank is a contributing factor.
Best fix is to braze around the bracket to the tank.

[Phatty]

Never thought of that. Don't have any oxy acetlyene. Got mig and tig and a lead loading kit.

[Capo]

If done correctly the braze will run under the bracket (which is spot welded to the tank) and then is built up over the bracket.

Make sure you gas free your tank before applying any flame lest you be surprised by a bang and an increase in the size of your tank.

[Phatty]

Yeah, my biggest concern would be fuel and paint still under the edge of the hinge. You're never going to get a clean weld with all that.

Tempted to grind the welds off and remove it. Clean it all back to bare metal and reweld it with a full seal weld all around.

[gary tompkins]

You may find the tank has partially rotted from the inside

Water collects at the lowest point of the tank and gradually eats through the steel

[Phatty]

It gets too much use for that to happen I'd have thought.

I'm going with the full tank and poxy tank stay being on the wrong side. It sould be on the side stand side, as thats the way the tank is naturally going to lean. That stupid stay pushes it further over.

Might take the tank off today and drain it.

[nuttynick]

I'd take the tank for a specialist repair, as it's likely to have rot elsewhere! Or better still find a decent s/h one.

[Phatty]

Took the tank off. Can't see any corrosion, although looking back through the pics now there is a bit of a rough area near where it's leaking.

http://i210.photobucket.com/albums/bb114/phatvr6/4db308dc.jpg
http://i210.photobucket.com/albums/bb114/phatvr6/9bbb985e.jpg
http://i210.photobucket.com/albums/bb114/phatvr6/4cd64631.jpg

[Phatty]

And a vid of the inside (apologies about the whining cat)

http://i210.photobucket.com/albums/bb114/phatvr6/8737530c.mp4

[gary tompkins]

Inside of tank looks surprisingly rust free in the video

Maybe it's a faulty weld that's started to leak?

[rac3r]

The cat did it

[Capo]

Never mind the cat fix that tap

[Saint aka ML]

My tank was also leaking there and is rust free inside.

Both Monster and SS tanks are now welded up by adding extra weld around the bracket.
From experience of welder that done few of them on Ducati removing it to clean that part of tank is real pain and not worth the gain. Just weld up all around and through that centre hole.

If it is done well A it will stop leaking and B no need to repaint tank as only damage to paint done is under the seat. Any pain to protect the area will do.

[Phatty]

Its melting snow dripping off the car port, not a tap! (thats frozen solid).

Gonna do exactly that, blast it in brake cleaner, let it all dry out, grind the paint back, fill it with CO2, and seam weld it.

[crust]

Very common fault on the old tanks.

Be carefull welding them, its easy to distort the tank.

Silver solder uses lower temperatures and does a better job as you can get it to flow under the bracket.

[Scotty]

what crust said

[Half Pint]

It happened to my bike and i went down the brazed route, pleased with the job and it worked well.

Although it does make a mess of the paint work:

http://i258.photobucket.com/albums/hh259/halfpint2008/IMG_0643.jpg

[Phatty]

Did it burn off the paint anywhere visible?

[Half Pint]

No, it was all below the seat height and underneath, I had my uncle respray the damaged bits so unless you look hard its not entirely visable.

[Duc600mon]

I drained out the petrol and put a piece of hose inside the tank and up the exhaust of my car and ran it on tick over for over an hour as (apparently) the exhaust fumes kill off the petrol fumes tendency to ignite! Then a mate kindly TIG'd it all the way round the bracket for me!
Sorted!

[Phatty]

Heard of the fumes trick before, but An hour??!! Tanks has been empty a few days now but still stinks. Was just gonna fill it with argon?

Gonna go along with the silver soldering method.

[Capo]

Heard of the fumes trick before, but An hour??!! Tanks has been empty a few days now but still stinks. Was just gonna fill it with argon?

Gonna go along with the silver soldering method.

10 - 15 min would be sufficient.
An argon purge would also work.

I remember Ken Sprayson (Renolds Tubes) at the TT applying his torch to the open fillers of tanks brought in for repair. Saw one go bang which pissed Ken off no end.

[Duc600mon]

Better safe than sorry!

[Phatty]

Hmm, i don't have a petrol car. Guessing diesel fumes wouldn't work? Will stick to the gas fill/purge.

[Phatty]

Bought some silver solder fluxed rods. Gonna get a mate who does car body repairs for a living to tackle it.

[Phatty]

Argon purge worked, but i ran out of blow torch gas!!

Better pic of the inside with the fuel pump removed.

You can see the spot welds on the right of the pic (left of the bike) have torn out of the tank skin.

http://i210.photobucket.com/albums/bb114/phatvr6/e4de0d50.jpg

Hoping to finish it off tomorrow.

[Phatty]

Looking closer at the above pic it would appear the spot welds have corroded as that os the lowest side of the tank when parked on it's side.

Got some soldering/brazing done.

Looks minging with all the flux crusted over.
http://i210.photobucket.com/albums/bb114/phatvr6/0086f57a.jpg

Quick run over with the power file to get the flux of and smooth things over a little.
http://i210.photobucket.com/albums/bb114/phatvr6/d75098d2.jpg

Still got to pressure/leak test it before paint.