On my recently painted Model A, The paint has lifted around the fuel fill pipe. Obviously this is from fuel coming in contact with the paint. How can I avoid this happening again when I repaint this area. Iím sure it is not from over filling, dribbling gas from the nozzle or a leaking cap as there is a gasket on the cap.
You mean like this:
I have the same problem.
Exactly. How do you cure that. Mine is even worse
What paint system did you use, Jerry?
I would look at the primer used on that tank. Maybe laquer primer. POR 15/Rust Bullet products work pretty good around gas. Time to get out the sandpaper!
On motorcycles I always tape about 1/4" from the sealing surface and leave it bare. Even with urethane clear it will lift at the edge if it contacts gas too often.
Guys I hate it for you. Been doing custom work for years and this is a normal. As Jim stated "lacquer primer" is the main issue. The other is a poor brand of paint or lack of activator. using an etching primer in a couple of light coats and going over it with a two part urethane primer works excellent. Sand and prep, then a good quality acrylic enamel or urethane with an activator. Masking the thread well area off well helps. Our modern fuel has other additives which are not friendly to core or paint products. Bare metal prep and working out with modern primers are the key to success. Unfortunately lacquer base primers of yesteryears are not compatible with modern paints or fuels and by the technical sheets provided by the manufactures of paints, have not seen any endorsements.
Hope this Helps,
All the Best,
Hank in Tin-A-See
Henry. I appreciate your information, but for me to fix this I need to do it with the tank in place. I could drain the tank for winter and then try to repair it then when there are less fumes from the gas in the tank. I do not know what Jerry would need to do.
I used an etching primer over bare metal, acrylic enamel with activator. No lacquer. Dave may have a great idea about taping off around the fill neck. Sure will hate to go to all the trouble just to have a repeat.
I painted my Harley almost 20 years ago and hasn't lifted yet.
The fill neck sticks up a little and I taped over the edge from the top. I used an epoxy primer/sealer under the primer and as a sealer before the paint. PPG DP40 is what I used.
Jerry, did you put the acrylic enamel direct to the etching primer? If so, that is your issue, that or if you left the etch exposed when finished. Gasoline will dissolve etch. For instance, you should use etch, urethane primer, then your acrylic enamel and make sure the urethane seals the etch and the enamel seals everything below that to ensure the gas doesn't get underneath.
Since you're talking about masking the neck, I assume this is a 30-31 tank?
BTW, DP 40 will lift lacquer...you have to remove the old paint if it is lacquer.
Is this tank vented or pressurized like on some speedsters?
Here's an idea that works very well on those caps that have a vent hole:
1. Solder a 1" copper pipe cap to the underside and drill a small hole in the bottom of the copper cap.
This creates an area for the gas to splash into and then drain back out.
2. Check the gasket. I found on my Torpedo tank cap that an oil filter gasket from a modern car fits perfect and is a bit thicker and seals better. The modern gas does not effect it either
31 tank and I used a sealer before the enamel. Is it possible that the neck leaks where it joins the tank. Should I jb weld to make sure?
I wouldn't think a leak there is likely unless you first saw the issue as a blister growing from underneath rather than from an edge. If you just painted all the way to the top and you cut the paint to where the gas could access the etch, that can cause the problem. You've got to think about the paint layers like your skin. Let's say you mask at the little shoulder that's on the neck that's hidden by the cap -- if you mask once: etch, urethane prime, and acrylic enamel, and then pull off the tape, the layers are exposed like strata and the gas can get underneath and do damage. If you remask each time and overlap by 1/64th or so, the edges are sealed. See what I mean? Then you have a neat edge and one you can wipe when filling the tank, rather than some unknown cut in the surface made when twisting on the cap.
Also, assuming you didn't mask off the neck and painted all the way to the top, your primer and paint is exposed inside the gasket area where it can get wet from gas frequently. By moving the masked area outside the cap gasket, so long as the gasket is good, it's only (potentially) going to get wet with gas when you're filling it rather than being exposed inside constantly.
Iíll try that. Thanks
That's exactly it, Walter...
I am by no means a paint expert, just throwing this out there.I painted the outside of the gas tank on our '23 TT that Dallas now has with Rustoleum Cold Galvanizing paint. I did spill some gas on it now and then, but it never showed any signs of lifting. Don't know if painting over that would help. Dave
Here's a couple pics of my bike.
You can see I put the epoxy primer on and retaped it a little farther away and painted it.
Hope this helps.
I have used DP 40 since about 1982 on bare metal with lacquer primer over it to fill sand scratches and minor pits because it sanded easy and held up well in my case for over 35 years now with a coat of reduced DP 40 over the finished surface as a sealer before paint. Never had the DP 40 lift any of the lacquer primer. This was what we were told back in the 80's by a PPG rep. to do for single stage or base coat paints. After the paint was cured, it would hold up to gas and even thinner but I never pushed my luck by letting it sit on the finish long. Now things have changed and the old DP 40 is replaced by DP 40 LF and we don't use lacquer anymore. The newer DP 40 LF is not as good and as I told the guys at the paint store, it just don't taste the same. The EPA has removed all the things that made paint and primers do what they were made to do so nothing will hold up against the gas that contains very little real gas these days. Then everyone wants to buy the cheap paint and expect it to hold up like the best stuff on the market. If you want it to last and hold up to gas I don't know what to use now because I don't do this every day anymore but I can tell you to listen to the guys that use it every day like Hank, they know what they are doing. Tractor Supply is not a good place to buy paint for a car and the spray can is no replacement for a paint gun.
On your in place fuel tank paint repair. Mask off well around the straps, etc. plug the filling hole the best you can. Then I would take an exacto knife and determine where the lifting has occurred. Primer from metal, paint from primer. etc. Reprep the metal and reprime You can feather in a blend paint, staging at the end coats using MEK as a blending agent.
Just trying to Assist
Hank in Tin-A-See