17 replies to this topic

[MrBounce]

I have a Mini van tank for my Midas. It's got a very minor leak - more like minor seepage - from the seam on one side (see pic). Would POR-15 seal this or am I better off

a) getting it welded or

b) getting another tank?

[Vulcan]

Frost have a number of solutions I believe.

[mini13]

Yes it should seal that OK,

I've used the por15 stuff to seal the twin tanks in my car and it goes on very thick, and if you have a particular seam that may be an issue you can leave the tank with that point at the bottom after you have swished the sealer round soi it puddles there and seals better.

Also I happen to have some por tank sealer that I bought bit didnt need in the end, I'll dig it out and check its all there (cleaner and sealer), providing it is you can have it for half what it is new.

[booton]

personally i would clean the tank out weld it and seal it.
i always like to thin what if i had a bump and i crushed the tank? would the sealer hold. A good weld would.

[dklawson]

Ummm when people talk about POR-15 there are a couple of things to be careful of regarding terminology.

POR-15 is an external coating, not for fuel resistance. HOWEVER, POR does make a fuel tank sealer using a similar paint chemistry. Their motorcycle tank kit is the ideal size for sealing the tank of a Mini. The kit comes with small bottles of their "Marine Clean" (caustic cleaner to remove fuel gum and varnish) and their "Metal Ready" (phosphoric acid metal etch). Of course, it also comes with a pint of their fuel tank sealer paint.

I have used several tank liners over the years. I much prefer the POR kit. It is easier to use and does not contain MEK which most other systems use. Prep your tank inside and out. Apply duck tape (gaffer tape in the U.K. ?) to the outside over any pin holes that need sealing. Remove the mesh strainer from inside the tank (on the fuel pickup pipe). Remove the sending unit and make a cover over the opening and have something ready to cover the fuel filler neck. Prior to using the kit, coat a large, heavy stiff electrical wire with Vaseline and insert it into the fuel pickup tube. Make sure it goes into the tank. You will withdraw this later to make sure the fuel pickup pipe remains open. Do the same for the vent tube.

Again, there is POR and there is the POR gas tank sealer kits. Though they are from the same company the chemistry is different. Don't use regular POR inside a fuel tank.

EDIT: Welding a tank is not for the faint of heart. It is also a skill that most people do not have since the tank is thin and these perforations open up at the seams where the drawn metal is extra thin. If you really, really hate the idea of the liner, strip the affected area to bare metal and solder over the area using a large plumber's soldering iron, acid flux, and large quantities of solder. Also keep in mind that the liner is closing a pin hole, just like the weld/solder will. Soldering or welding does not add strength to the tank. You are not better protected by using welding/soldering as opposed to the liner.

Edited by dklawson, 02 October 2012 - 09:01 PM.

[bmcecosse]

Seriously - it's for petrol - get a new tank!

[dklawson]

Roy! Yes! It's for gasoline!

That doesn't mean that lining the tank is in any way "bad" or "unsafe". Tank lining has long been performed to prevent rust/scale from creating pin holes and to seal the ones that do form.

[Barman]

Ummm when people talk about POR-15 there are a couple of things to be careful of regarding terminology.

POR-15 is an external coating, not for fuel resistance. HOWEVER, POR does make a fuel tank sealer using a similar paint chemistry. Their motorcycle tank kit is the ideal size for sealing the tank of a Mini. The kit comes with small bottles of their "Marine Clean" (caustic cleaner to remove fuel gum and varnish) and their "Metal Ready" (phosphoric acid metal etch). Of course, it also comes with a pint of their fuel tank sealer paint.

I have used several tank liners over the years. I much prefer the POR kit. It is easier to use and does not contain MEK which most other systems use. Prep your tank inside and out. Apply duck tape (gaffer tape in the U.K. ?) to the outside over any pin holes that need sealing. Remove the mesh strainer from inside the tank (on the fuel pickup pipe). Remove the sending unit and make a cover over the opening and have something ready to cover the fuel filler neck. Prior to using the kit, coat a large, heavy stiff electrical wire with Vaseline and insert it into the fuel pickup tube. Make sure it goes into the tank. You will withdraw this later to make sure the fuel pickup pipe remains open. Do the same for the vent tube.

Again, there is POR and there is the POR gas tank sealer kits. Though they are from the same company the chemistry is different. Don't use regular POR inside a fuel tank.

EDIT: Welding a tank is not for the faint of heart. It is also a skill that most people do not have since the tank is thin and these perforations open up at the seams where the drawn metal is extra thin. If you really, really hate the idea of the liner, strip the affected area to bare metal and solder over the area using a large plumber's soldering iron, acid flux, and large quantities of solder. Also keep in mind that the liner is closing a pin hole, just like the weld/solder will. Soldering or welding does not add strength to the tank. You are not better protected by using welding/soldering as opposed to the liner.

Great response!

[ace01]

The one note of caution I would add concerns ethanol. I have a right hand tank in my Cooper that has been sealed with Frosts excellent kit. At the moment it is sealed well and has been for several years, but I have been noting the warnings about ethanol, which will apparently turn the seal to a jelly. Do Frosts have any comment on ethanol?

[bmcecosse]

That won't be the only weak point in the tank - for peace of mind, just get a new tank. You know it makes sense. As for fiddling about with a soldering iron on a rusty old tank - good luck!

[JVA10L]

That won't be the only weak point in the tank - for peace of mind, just get a new tank. You know it makes sense. As for fiddling about with a soldering iron on a rusty old tank - good luck!

bmcecosse;

I'm sure I remember you brazing a patch onto the tank of your autocross mini - and a flame like a pilot light burning on the fuel outlet pipe. It was more than 40 years ago so you 've had time to re-consider this method.

[TopCatCustom]

Personally I have never used a tank sealing product, but I imagine it would give a better result than trying to weld a rusty tank, you'd do incredibly well to get all the rust and contamination out of the whole affected area so that you could get a clean perfect weld without it spitting and creating more pin-prick size holes.

Also a vessel containing petrol won't just explode, it's the vapour, so I personally don't see it being any more dangerous than any other old petrol tank. The dodgy fuel lines on most old cars pose more of a threat.

[dklawson]

The one note of caution I would add concerns ethanol. I have a right hand tank in my Cooper that has been sealed with Frosts excellent kit. At the moment it is sealed well and has been for several years, but I have been noting the warnings about ethanol, which will apparently turn the seal to a jelly. Do Frosts have any comment on ethanol?

The POR tank lining kits are perfectly fine with ethanol. I am not trying to "one up" you regarding this but the U.S. has been putting ethanol in its fuel for a couple of decades mainly as a method to lower emissions. Ethanol is blamed for absolutely every running problem you can imagine. Regardless of how many ethanol urban legends may be true in whole or part, ethanol does not affect the material in POR tank lining kits.

The main point I will stress about tank lining is that it is basically a painting process. Like ALL painting, the quality of your results are almost 100% based on the effort put into preparation. Clean (I mean really clean) the inside of the tank before applying the lining material and follow the instructions to the letter.

As for the kits that Frost sells... I don't know. I know Frost is (or was) a distributor of POR products so they may be a source for the POR tank lining kits. Again, the motorcycle tank kit is more than big enough to coat a Mini fuel tank.

EDIT: And Roy, I have soldered over pin holes in tanks before. As I mentioned, I strip the affected area around the pin hole and bring it up to a clean appearance. I use acid flux (resin will not work) and a very hot, large plumbing iron. Smaller irons will not transfer the heat fast enough. You tin the surface first to make sure the solder wets the surface then you come back and make a second pass applying a heavy layer of solder to bridge any pin holes. Apart from using a plumbing iron (instead of a torch with a soft flame), this method is not unlike doing lead bodywork.

Edited by dklawson, 03 October 2012 - 12:27 PM.

[Big_Adam]

Or take the tank off, fill it with water, air it out, fill it, go over the tank with sand paper to find any other rusty leaky spots, then take it to a welder who can do petrol tanks.

Then again, I seem to live in a magical fantasy land where machinist, imperial tool, and bolt shops are all in walking distance.

Edited by Big_Adam, 03 October 2012 - 01:10 PM.

[mk1leg]

If in doubt get a new or good 2nd hand tank............as welding id dangerous.............I've seen one explode........not a pretty sight....