What's your favorite goo to slather in a fuel tank? No leaks just looking to seal the surfaces from rusting. Preferably available on the US side of the pond.
This is a sore point Larry. I now have three bikes that I have used PETSEAL in years ago that must now be stripped because the ethanol in our petrol has started to break it up. You need to check the stuff out on the internet to be ethanol proof. Ron
You and me too Ron, sold a bum steer by petseal , even got two cans of the stuff unopened I didnt use because I heard of the problems folk were having, Found a product called TAPOX, Made in USA I think, any of our frends in the USA use it, scared to use anything now just in case it causes me loads more work, andrew.h.
I used Tapox and found it was a lengthy process..very lengthy. Also curing time was slow and they were , lets say, optimistic, about the quantity supplied..Oh,and it was expensive. (but it did work)
Draganfly do one which is a lot cheaper and guaranteed Ethanol proof...so I would try them.
The general concensus is that Ethanol absorbs water from the atmosphere..so the presence of petrol in the tank could be worse than if it was empty..Petrol floats on water so the accumulated water would sit there along the bottom and seams of the tank...Ian
There seems to be an inherent flaw when it comes sealing tanks and this is when you put the tap in, invariably where the tap sits, there is an edge to the sealer that is constantly under the fuel and over a period of time the fuel gets under it and starts to lift it. I'd much prefer if possible to keep the rust dust down by using a paint instead of a sealer (poured in and rolled around) but only a thin layer, but the question is what paint can withstand it? I prefer the method of putting sharp gravel in the tank and wrapping it in an old duvet and put it in a cement mixer for a while varying it's position so that it goes all round the tank, and then flushing it all out with petrol and blowing it dry with an air line.
If the tank is leaking, it is a far better idea to repair the tank either in the form of brazing, or if it's a porous area then get it cut out and a patch of clean metal put in there. Consider cutting out the whole bottom if necessary, on an M20 it isn't too hard to fabricate it is only a flat piece of steel with a slight radius on the edge, it just sounds more daunting than it actually is. To get the radius on the edge you simply carefully hammer it over any hard object to create the radius. keep the piece you cut from the bottom and use it as a template adding a 1/4" to it all the way round and then carefully grind it to fit snugly then even if you can't weld it yourself you could take it to any welder to get gas welded (mig and tig don't seem to give the correct form to the weld) Ask your welder if you can fetch it back if you find any pinholes in it which invariably it will have.
To stop the tank going bang when you put the gas torch/grinder near it, simply put an air line down it for about 10 minutes and if it dosen't smell of petrol it is probably ok, if in doubt leave it on for another 10 minutes and just to be extra sure before you weld it put it round a corner and then from the safety of being round the other corner, put the gas torch down the filler hole for a couple of seconds and if it dosen't go bang then, it probably won't go bang. Be very careful, but basically using this method, if it dosen't smell it is ok. Believe me I wouldn't tell you to do this if it was at all suspect, yes, you can purge it with a car's exhaust or fill it with water, but it makes any filling of pinhole leaks tedious. I have had a car petrol tank explode on me, and it blasted towards me and then hit the roof about 12 feet up- very scary but I was ok, but out of all the methods I've tried the airline method is the safest. It seems that as restorers we will spend hours on restoring the smallest part, but when it comes to petrol tanks we go all scared and in effect only put a "plaster" on them when in reality we run the risk of it being more dangerous by not repairing it properly
PS, Army standards for petrol tanks were to put 5 psi in them and then immerse in water and check for air bubbles. Don't be tempted to just put it in at any pressure as it WILL distort the tank. If you have a leak down tester, you can soon find another use for it doing this. I don't think the filler cap would hold 5 psi !!!
Dave (or anyone else who may have tried it): when removing and re-welding the bottom of the tank, have you ever tried to enlarge its capacity? Sometimes 3 gallons are not enough for long trips and I would like to space out fillups a little more, even though I know that would be a non-standard mod.
It wouldn't be too hard in theory, but in practice there isn't a lot of room under the tank before you hit the spark plug! but like everything it is do-able, you would just lengthen the depth of the tunnel and extend the sides downwards then fabricate the bottom.
Hi Larry, if it ain't broke.. don't fix it..! as they say.
I would put some small nuts and bolts in the tank (count them first) and give it a good shake to dislodge any loose rust, but otherwise I wouldn't worry. Make sure you have a wire gauze fuel filter over the tap.
I've never been a believer in petseal, but I have repaired leaks on the outside of the tank with instant metal or similar 2 pack resins. This was after the bottom of a tank was cut out to repair a very bad dent. We couldn't get the weld to be petrol tight. This was 20 years ago and the resin is still on the tank now.
Dave (or anyone else who may have tried it): when removing and re-welding the bottom of the tank, have you ever tried to enlarge its capacity? Sometimes 3 gallons are not enough for long trips and I would like to space out fillups a little more, even though I know that would be a non-standard mod.
John, if you want a larger capacity on an M20 then you need to modify one of the early tanks. They should have a larger capacity but have the huge cut-outs underneath to take even the tallest ohv engine. For some reason when they fitted the WD base, it was decided to make the tank smaller, giving them the same capacity as the earlier tank.
Nortons kept the same top pressings when they fitted the sv WD base and a WD tank has a usefully larger capacity than a pre-war civilian equivalent.
I've used Kreme brand in my MGA tank. Never again. I had to buy a new tank after 3 years asit all peeled off. there was so much I could not get rid of it.
Hi Guys & Girls
I have used POR 15 in fuel tanks and inside primary cases that have rust holes in the last 12 months. other club members have used it over the last couple of years in fuel tanks,air boxes and header tanks for military vehicles with no bad reports as of yet.
Thanks Ron, not keen on sending more money there way as I have at least two tanks to declag of this petseal, and ethenol and similer has been used in fuels for many years, remember clevlandiscol,But its got to come out,and I move on, andrew.h.