Fuel and oil tank sealants

Tried a sealant once and had more issues when it failed than it ever solved. I grind the bobbin down to match the surface height and then get a plate welded or brazed over it. After painting I then stick a thick pad over the plate so the tank just rests on the support by the paf. I upgrade the 2 upper mounts to thicker versions and then fit the tank. Stays in position and never leaks.

I have successfully used POR 15 on many tanks and it works perfectly. It is very important to clean the inside of the tank very carefully and to ensure that it is dry before using POR 15. My preparation involves using caustic soda to clean out any gum, hydrochloric acid to remove rust, phosphoric acid to passivate the surface and alcohol to remove the water. Others prefer to clean the tank using old nuts and bolts but that is very hard work.

Before I discovered POR15 I used Petseal and Petseal Ultra. They worked badly for me and were not ethanol proof. Even worse, on first use the resin dissolved in the petrol and then collected on the throttle slides, jamming them wide open. I'll never use it again!

Hi,

A very interesting thread and on a couple of fronts. It is always interesting to hear of other members' experiences.  

The oil tank on my commando has lost the bobbin on its bottom and a plate has been welded across by a previous owner. I was going to weld a nut to this so that I could pass a bolt through the grommet in the battery carrier to restore the fixing regime back to original. From what I am reading here, this might prove not to be such a good idea after all, since it would appear that my bike has suffered from a similar problem as had John; perhaps this is a fairly common problem?  Any comments anyone, before I get out the MIG ?

I have used POR15 and it seems to be very good. I am intending to use it on my Commando petrol tank but the worry is always drying it well enough; it is a big tank and there is a lot of opportunity for trapped moisture.  I am intrigued by the use of alcohol - what type and how?

Thanks,

Keith

Yes its a common problem, the first time it happened to me in the 80's I bought a new tank, only for that to go in the noughties, same place same issue cracks in the steel next to the bobbin. So then I copied a fix I found else where. Even if you put a new plate over the top of the old bobbin the new bobbin with bolt will still vibrate and fatique the surrounding steel, the thicker steel may resist longer but it will still go eventually. So the fix is just to support the tank on a pad and then to beef up the support at the top where another common fault is for the buffers to split. With the side cover in place with its tab at the bottom the tank is going nowhere even without the bottom bolt.

So add the extra plate to cover any existing cracks but do not refit the bobbin.

Hi John,

Thanks for that good advice. I shall certainly follow your example. It will save me some work as well!!

BR,

Keith

PS. I had assumed erroneously that the tank fixing was yet another of the many bodges that I have uncovered!

www.tankcareproducts.co.uk The guys name is Ian Potter and he's in Norfolk, when ethanol destroyed the liner in my fuel tank ten years ago he removed it all and replaced it with one that's ethanol proof, I've never had any issues with the liner since and there is always fuel in the tank as the bike is used.  He also sells the kits for DIY , have a chat with him, he's a nice bloke.....Ady