Leaking fuel tank

[MickS2]

My fuel tank has started weeping through the joint where the rim of the retaining ring for the internal filter access plate is spot welded to the bottom of the outlet bit of the tank (that is, it is leaking through the metal to metal joint, not around the rubber gasket)
So, do I try one of those DIY internal tank sealant coatings or get it welded by a brave welder or splash out for an expensive ally tank or a horrendously expensive stainless one?
My fears are that the coating stuff either will not work or later flake off to clog up the fuel system. Some say that an ally tank is vulnerable to splitting due to stone damage from the rear wheels. Stainless is too expensive, which leaves welding. Is it easy to find a welder willing to have a go and what are the chances of there being a pinhole leak through the weld once it is all done? Also will the 18 year old tank stand being welded? What are the chances of getting a new rubber gasket to seal after removing it for welding - the locking tabs and retaining ring look a bit worse for wear. How about cutting the inspection bit out and getting a flat plate welded across the bottom of the outlet bit?
Any thoughts or experiences?
All advice appreciated
Mick

[GreenV8S]

I think you almost certainly need a new tank. I would have thought that a small leak now is probably the first sign of corrosion damage which is going to get worse and worse over time.

In the meantime, you can get sealant specially designed to push into cracks and crevices to seal it, and in fact chewing gum actually makes a very good permanent repair for many petrol leaks if you can get it to seal initially (it gets harder and stronger with age and is completely impervious to petrol). But if the tank is getting worse (as it probably is) then stopping this particular leak will only buy you more time. Sooner or later you will need a new tank.

[mwbs3]

Hi Mick

I had an ally tank made for my S3 inc new frame for £320 ex vat from 'allisport' they have a web site.

If you would like more info please let me know.

Thanks

Mark

[ralph s3]

I used JB Weld from Halfords. Worked a treat.

R

[spivvy]

i used and internal sealing kit from frosts had no problems with it and that was over 2 years ago

[MickS2]

Thanks for the info chaps.
Looks like I have a few options. For peace of mind my gut feel is to go for the replacement tank. I have been quoted £616 for a stainless one (off the shelf) and £450 for an ally version (2-3 weeks to build) so Allisport looks a good option - do they need my old tank as a pattern to work from? Still a bit nervous about an ally tank though.
An internal coating (with JB weld on the outside for good measure) would be a much much cheaper option though.

Decisions, decisions!