Leaking fuel tank?

Deluks · 8 Oct 2008

I've recently noticed a damp patch on the underside of my petrol tank ('91 Polo)

Not peeing out or dripping, but enough to worry about.
Finger it and sniff reveals that this is petrol, which I assume is coming out through a pinhole in the tank somewhere, as the tank is fairly corroded. More than likely the join between the filler pipe and the tank itself.

Is this repairable, or is there a product than can be used to seal it (once I can locate where it's coming from)

A new tank will be about £70, and is definitely planned for the future but is there any way to temp repair it in the meantime. MOT is due in a few weeks, and I'd rather do a basic to get it through than have to fit a new tank, which I would rather leave for a couple of months.

^neo^ · 8 Oct 2008

Not really unfortunately.
Could try ebay or edition38 / clubgti forums for a 2nd hand one, loads of bread vans being broken up !

L_Plate · 8 Oct 2008

We had this happen on a '93 Polo that my family owned a few years back. It is a common problem on Golfs and Polos of this period. The leak comes from the filler neck; not actually the tank itself so the smell will no doubt be at its most intense after filling. It is possible to obtain a fibreglass neck repair kit but it is as expensive as replacing the entire tank. We got ours from Europarts for about £80, if I recall, and it cost a similar amount to have fitted. Incidentally, it is also slightly larger than the original tank by about 5 or 6 litres. To do this the fuel system needs to be depressurised, so it might be worth considering replacing the fuel filter whilst you are about it.

The motor was in the family for eight years and this was he only item that ever required replacing, other than service parts that iis.

nickso · 8 Oct 2008

get a second hand one.

you could weld your current one but you would still need to remove it to do it and welding the filler neck is usually a pain on most cars.....easier just to put another one in.

jonnyboyz28 · 8 Oct 2008

If you know where it is leaking from clean it up and paint it with fibreglass resin. This will last for ages.
There is also a product specifically for sealing up porous tanks, I think it's called POR 15, but from the write up you need to remove the tank and flush it out before using the stuff, and it's not cheap, so I would probably rather spend the money and time on fitting a new tank in your situation.

Belle427 · 9 Oct 2008

http://www.frost.co.uk/item_Detail....tCat=Gaskets & Sealers&frostSubCat=&subCatID=

this any good?

Deluks · 9 Oct 2008

Thanks for the help chaps, you've all been very helpful. I've been offered a tank for £20 from a guy on eBay who's breaking a Polo. He reckons it's in good nick but at least I'll have the chance to inspect/repair/paint before it's put on the car. My only reservations are that it might get damaged during shipping, as it's too far for me to collect, and that fitting will be tricky.
I've got the Haynes manual but fuel tanks on older Polo's are supposed to be a P.I.T.A. to fit.
Particularly for the average car DIYer like me.....

Using carpentry tools

cakeman · 14 Oct 2008

filler necks are famous for it
caused by filling up to the very top on a regular basis
you'll see where underseal has peeled away
fix :-
sand down the leeky part(usually where the neck joins the tank)
make sure its perfectly dry
use petrol tank filler to smother the area
re paint with underseal
only use tank upto third or half full
far less hassle
will last long time if done carefully

HTH

Softus · 14 Oct 2008

£70 for a brand new tank, with a warranty, delivered to a garage near you?

Rip their arm off.

ericmark · 13 Oct 2009

Soft soap reacts with petrol and will seal small hole. Get a bar of soap stand it in dish of water to get it a little soft and then rub it on tank until you can get full repair.

Does not work with diesel only with petrol.

Burnerman · 13 Oct 2009

These tanks are dead easy to fit - 4 bolts and the rear exhaust section needs to be dropped. There is a difference between the carburetted and injected tanks - the well that the fuel pump sits in is deeper on the injected vehicle. Cheers John

Deluks · 14 Oct 2009

Job done ages ago and new tank fitted, eventually. Repair got me through the MOT initially though.

Burnerman, try that on your back, under the car with the wheels only 8" off the ground, and a pattern tank that's got the pipe at the wrong angle. Then tell me it's dead easy

JohnD · 14 Oct 2009

I've been through it too. Fitting a new tank was far better than patching up the old one (which I did try) . Though I did take care to give the new one some preservative primer and gloss paint before fitting. the maker's paint was not very convincing and mine had gone rusty where wet mud lodged against a welded seam.

Burnerman · 15 Oct 2009

Deluks said:
Job done ages ago and new tank fitted, eventually. Repair got me through the MOT initially though.

Burnerman, try that on your back, under the car with the wheels only 8" off the ground, and a pattern tank that's got the pipe at the wrong angle. Then tell me it's dead easy

I've done 3 tanks that way...agreed its not the most pleasant, but there again I don't waste my time trying to seal rusty tanks up. Cheers John

ericmark · 15 Oct 2009

Did try welding a 60 gallon tank once.
Steam cleaned all morning then positioned with concrete block between me and tank. It went bang even after all that steam cleaning never tried again.
Because it was off a 1938 6 x 6 MACK I could not get replacement off shelf so then had to make new one from sheet steel. If available I would not repair other than get me home fix which would likely be soap method.

Leaking fuel tank?

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