Topic: Pinhole In Freshly Painted Tank

[RickB]

Hi all,

I've also posted about this over in my project shop build thread, so apologies for the double post but I need some advice.

Ok so when starting the motor for the first time on, I also filled the petrol tank for the first time. Stupidly, I didn't think to put petrol in it before I had it painted. Well, it has a leak. It's two tiny holes below the rear mounting bracket that sits on the rubber pad.







As you can see, they're not huge or structurally compromising in anyway. Can anyone suggest a way to best repair this? Obviously I can line the tank with POR 15, but the inside is rust free so it seems a bit extreme. I could have someone weld it perhaps, but does paint complicate this? I could fill it with some sort of fuel resistant epoxy? I've heard soldering can work but again, does paint affect this? It's not exactly in the easiest to get to of places what with that bracket.

Any suggestions?

Rick.
Rick.

[axehole54]

leak that small you should be able to use a fuel compatible 2 part epoxy but you may have to take it down to bare metal in that area

[RickB]

Yeah that's what I thought. It's so small that a dab of some type of glue/epoxy would do it. It's just a matter of, how long does it hold you know? Like it'll fall out eventually. Still, I like the idea of fixing it soon. How I'd sand back that fresh hard paint in such a hard to reach area is another problem!

Thanks,
Rick.

[axehole54]

dremel with a small sanding drum?

[RickB]

That's one tool, the dremel, that I have found excuses not to buy every time I've needed one. I don't own one, might have to pop into the panel beaters and ask for 10 minutes on there one.

[bender01]

Permatex makes a gas tank repair kit. Its a tube of clay like stuff you roll til its mixed and apply! I filled a pencil sized hole on a tank once on the under side without problems. It turns hard as a rock. Your hole may be too small for it though.

[HondanutRider]

Permatex makes a gas tank repair kit. Its a tube of clay like stuff you roll til its mixed and apply! I filled a pencil sized hole on a tank once on the under side without problems. It turns hard as a rock. Your hole may be too small for it though.

I second this product and approach.  Did the same thing, successfully on my CB350F tank.  As well as sanding the area clean with a dremel sanding drum, once the area is clear and the pin-hole exposed, you can open it up a bit if needed, to allow this putty seal to be forced into the hole and create a blob on the exposed side to adhere to the bare metal exposed.  The nice part about the location of your leak is that it is in an unexposed area that won't mare your new paint job - just touch-up over the patch afterwords and no one but you will know its there.

[RickB]

Thanks guys.

I checked the webs for my local auto parts store and I can get Permatex tank repair strips here. That's good to know.

Bowser you don't think this would just fall out in 6 months? I'd hate to be riding along and have fuel start dripping out. It is a tiny hole though, maybe the Permatex stuff is permanent enough? What do you think?

If I'm sanding it back to bare metal anyway I might as well get someone to give it a quick zap with a welder is my thinking.

Rick.

[Johnie]

So you know you got the pin holes, but you have no idea how thick the area around the pin holes are? It could be paper thin. Just wanted to be sure you are aware of that possibility. You could have a spot weld done, but if it is thin you will have more show up. You may also start the grinding on that area and your pin hole is now the size of a dime. I had this same deal on my KO tank. I was bound and determined to keep the tank on this KO that the bike was born with. I had it sealed and rode it 2 months before I painted it. Well, my new paint job started to bubble just south of the gas cap. Yup, pin holes possibly from when the painter sanded to bare metal. Had a special epoxy "for gas tanks" put on the pin holes. Painted again...bubble again under the paint. I would try once more, but this time went all out with a new liner and had the tank stripped and silver soldered. That did the trick and it has been good. I hope you can get yours done with the epoxy, but those 2 pin holes are telling you it is getting thin in that area.

[ekpent]

I would patch the hole from the outside and  put a gas barrier on the inside,I have used Red-Kote. Even though the tank looks clean inside its obvious that you have some thin metal and maybe more problems down the road.

[Kong]

You're lucky in a way, its on the bottom.  Clean the area around the leak to bare metal and solder it ... or braze the area (brass rod) and repaint the tank.  If you solder it you can then just touch up the effected area and be on your way.  If you do decide to braze and repaint, which is what I would do, go ahead and take the entire tank to bare metal first to make sure you've got a good foundation to repaint - and if not, replace the tank.

On Edit:  By the way, I love the color.

[Johnie]

I like the color too. How about a pic of the bike    You know we like pics here.

[octagon]

you can take a light hammer plus an ice pick (or a punch with a sharp point) and tap around the area to find out if the metal is thinned on the inside form rust. go over the whole bottom of the tank that way.
do light taps, and the point of the pick or punch will bounce back off the metal. if you get an indentation that tells you the metal isn't strong enough. worth doing a careful survey of the whole tank bottom before you go further.
you can also tape a small flashlight on a piece of dowel and shove it down into the tank to get a better look at the interior surface.

[Terry in Australia]

G'Day Rick, I'd go the POR-15 route, as has been said (above) you've probably got some very thin metal there, water collects in low depressions in these tanks and while it might look great from the outside, inside it might look like a lunar landscape of rusted craters just waiting to produce more pin holes.

I POR-15 all of my tanks now, if done carefully it won't buggar your paint, and the stuff sets rock-hard. I've used the "fuel tank and radiator repair kit" that you've mentioned before, but (as the manufacturer stresses) it's only a temporary fix, and in my experience using it on cars, it's good for a few days to a couple of years, before it shrinks and falls off. Cheers, Terry.

[faux fiddy]

G'Day Rick, I'd go the POR-15 route, as has been said (above) you've probably got some very thin metal there, water collects in low depressions in these tanks and while it might look great from the outside, inside it might look like a lunar landscape of rusted craters just waiting to produce more pin holes.

I POR-15 all of my tanks now, if done carefully it won't buggar your paint, and the stuff sets rock-hard. I've used the "fuel tank and radiator repair kit" that you've mentioned before, but (as the manufacturer stresses) it's only a temporary fix, and in my experience using it on cars, it's good for a few days to a couple of years, before it shrinks and falls off. Cheers, Terry.

Can you pour the product into one corner of a takn as her and expect it to work or are you committed to liner the whole tank with it?

I know the kickstand side tends to get more rust  and holes as here...Can you just por-15 one corner or side of a tank?

[Terry in Australia]

G'Day Rick, I'd go the POR-15 route, as has been said (above) you've probably got some very thin metal there, water collects in low depressions in these tanks and while it might look great from the outside, inside it might look like a lunar landscape of rusted craters just waiting to produce more pin holes.

I POR-15 all of my tanks now, if done carefully it won't buggar your paint, and the stuff sets rock-hard. I've used the "fuel tank and radiator repair kit" that you've mentioned before, but (as the manufacturer stresses) it's only a temporary fix, and in my experience using it on cars, it's good for a few days to a couple of years, before it shrinks and falls off. Cheers, Terry.

Can you pour the product into one corner of a takn as her and expect it to work or are you committed to liner the whole tank with it?

I know the kickstand side tends to get more rust  and holes as here...Can you just por-15 one corner or side of a tank?

Yeah mate, theoretically you could, but you'd be better off doing the whole tank, that way you'd have an impenetrable membrane over the entire inside surface of the tank, and no chance of anything getting under one corner and working it's way between the sealer and the unprotected metal. Cheers, Terry.

[RickB]

Thanks for all the advice guys.

I had a good look at the tank in the sunlight today. From what I can see (which I supposed is the big "if") it appears to just be the two small holes in the weld that holds the bracket on. I tapped around it and it all appears solid. I suspect the weld along that edge could be bad, but with the paint on and the condition of the rest of the tank, it looks great.

Given the the holes are right under the rear mounting bracket, it'll require some cutting to get to if I wanted to weld or drill it out, so I think the Permatex stuff will allow me to push it in and under with a putty knife.

I think I'd gonna' try the Permatex stuff. It'll be a pea sized amount and will take no time to do. If it leaks, then I'll have to do it properly.

As they say, the poor man pays twice. I suspect this is going to be an ongoing saga.

Rick.

[RickB]

So I found some two part epoxy jointing stuff called Ferropre in the shed. The old man says it's great for sealing things and is hard as nails. The trouble is, I can't find anywhere that says it is resistant to petrol. Then again, I can't find anywhere that says it isn't.

I think it's an Australian only thing (it's sometimes referred to as Jenco). Does anyone know if that'll do the job?

http://www2.bakers.net.au/DisplayProductDetails.aspx?part_no=00512448

[mick7504]

I've seen ferropre used on PVC storm water and sewer pipe joints Rick but I don't know if it handles fuel.
The POR15 teatment will be good insurance against any potential further problems.
Mick

[larry]

I'm in the process of stripping down my tank for painting now.  Did a quick search on how to test for leaks and didn't find much.  Any ideas?  Also was suggested I sand blast the tank another suggested glass beading.  I'm leaning towards beading partly cause he'd do it free.  Thoughts?

[ekpent]

If you go with just the patch route and do not do the inner pin hole/tank seal than maybe you should consider just using JB Weld on some good prepped metal (no paint scuffed up) or check out a gas resistant product called Seal-All.   http://www.google.com/products/catalog?rlz=1T4HPIC_enUS307US307&q=seal+all+glue&um=1&ie=UTF-8&cid=6170833892599708899#

[Johnie]

Someone asked how to test for leaks...take it to a radiator shop. They can pressure test it there. As far as liners I like the Red-Kote too. Seems to be one of the liners that I have not seen any complaints about.

[BeSeeingYou]

I would go for the JB Weld.  It has a consistency that will fill small holes unlike Permatex which is more like chewing gum.

[Grabcon]

There seems to be a lot of how to after the fact of painting. So with that said here is the obvious. Especially after blasting do a leak test. Blasting removes material and leaks are common after blasting.

Prior to leak testing go to the hardware store and pick up some leak soap for testing natural gas line connections. For a pressure test I would use an accurate gage and no more than a few pounds of air. Then take the leak soap and follow the instructions and do all seams and welds, petcock, around the filler cap etc. Look the for bubbles.

If you can not test under pressure use water or antifreeze or non flamable liquid. Antifreeze has a low specific gravity and will find leaks. Mark all leaks with a marker. Drain and rinse tank. I would braze or weld the leak areas. Retest. Once the leaks are fixed and final pressure or wet test is complete thoroughly rinse tank with acetone and allow to completely dry prior to painting.

If you want to line the tank now is the time.

[stueveone]

+1 on JB Weld. I've used it twice now, two difference applications. One of which is still holding strong with no signs of fuel weeping 5 years later.