Topic: Painting around flush gas cap

[q2418130103p]

I know that normally you keep the fuel neck rim bare metal to avoid getting gas under the paint.  But what do you do when using a fuel cap like this:




My tank is freshly painted, and it uses one of these caps.  I masked off the holes for the fuel cap from the inside only, so the paint currently goes around the edge of the holes which will certainly not work out well.  I was planning on sanding off the paint until just past the screw holes, then apply some sort of sealer.

[q2418130103p]

I dont think this unit is that fancy:

[crazypj]

Use epoxy instead of sealer (JB Weld or similar)
 'Glue' the inner piece inside tank as well

[Retro Rocket]

Use epoxy instead of sealer (JB Weld or similar)
 'Glue' the inner piece inside tank as well

+1, i wouldn't use JB weld on fibreglass though, i would go with a 2 pac epoxy product. If you were near me i could give you some, I use industrial expoxy's for work and we get it in 20 liter drums, always some laying around....

[crazypj]

Haven't been following thread too close, didn't know tank was F/G

[q2418130103p]

The tank is steel.

So besides epoxying the inner pieces on, should I just put a thin coat everywhere beneath the cap?  Basically where ever the gasket will be.

[Retro Rocket]

Haven't been following thread too close, didn't know tank was F/G

Looks like its steel.....

The tank is steel.

So besides epoxying the inner pieces on, should I just put a thin coat everywhere beneath the cap?  Basically where ever the gasket will be.

You could but if you ever want to remove the gasket it will be a real #$%* with epoxy. Do you guys have sikaflex in the states, its like silscon sealent but better and stays soft {rubbery} so it would be easier to get off....

[FuZZie]

The automotive (high temp) gasket stuff you get in the tubes should work, I believe it's also fuel resistant too. 

[q2418130103p]

Well I wasn't planning to epoxy the gasket on, I figured I would let it dry before putting the gasket on.

[crazypj]

I would epoxy the inner pieces (using the top to align things, make sure it's greased up though)
 Then, dismantle, clean and use the gasket after epoxy has hardened

[q2418130103p]

O yeah, you probably noticed that I didnt actually flush mount it... I got lazy.

[q2418130103p]

I would epoxy the inner pieces (using the top to align things, make sure it's greased up though)
 Then, dismantle, clean and use the gasket after epoxy has hardened

I think I still have to sand some paint back as well, at least to get it off the inner edge.

[crazypj]

Yeah, I see what you mean about paint, that's why I wasn't sure.
 Definitely needs removing

[Triffecpa]

first off, cool gas cap.  Where does one find such a thing?

Second.  If I am looking at this thing correctly, the cap with it's surround sits on top of the tank with the gasket underneath it.  The six bolts go thru the collar and gasket and tank and into the two U shaped pieces that are placed inside the tank.  right?  Can you not sit the gasket and cap/ring into place, open the cap and then insert the U shaped pieces thru the opening and hold them in place whilst you start the screws?  If you can do that, then are you concerned about the gas leaking up thru the threads?

Tracy

[crazypj]

They are on e-bay
 Custom Chrome made them (at least the one I have)

[q2418130103p]

I got mine from custom cycle engineering.  I am not sure about the custom chrome ones, but the one I have is a repackaged newton equipment cap.  If I remeber correctly ist is about $150 from custom cycle, and $300 from newton.  It even still has 'newton equipment' stamped into the bottom of it.

Anyway, tracy, you perfectly described the setup and installation of the cap.  But I am not concerned about gas leaking out of the tank.  What I am concerened with is gas getting under the paint.  I dont believe it is a good thing to have paint end in a place where it can make contact with gas, which is why the area around gas caps is usually bare metal.  My problem is that there is not very much space between the edge of the flange and the screw holes, so I am a bit hesitant to remove paint from around the screw holes.

I think my current plan is to remove paint from the inside edge of the main hole, and sand up to just under where the gasket sits.  I will then sand a bit around each screw hole, and then seal the new paint edge with some kind of epoxy.  Maybe something like this http://www.craigscustoms.com/media/Lip_Seal_finished.pdf



My second dilemma is that I have to send the tank out to have the liner removed, which I know is a scary process.  I am not sure if I should sand and seal this before or after sending it out.  Anyone know how they go about removing the liner and not wrecking the paint?

[crazypj]

That looks like Araldite epoxy re-packaged?

[Kong]

Your concern is justified.  Don't use some sort of two-tube-epoxy crap to try and seal the tank.

It would have been best if you had masked to the inside centers of the screw holes that hold the hold-downs and gasket in place.  With what you have now you should be in pretty good shape with a little sanding though.  Here's how I'd address it from where you are.  First I'd tape and mask the tank from the mounting holes out.  Then I'd sand from the mounting holes in but only be concerned about having bare metal exposed for about 1/2" out from the filler hole.   Next mask the inside of the filler hole.  Then I'd get an airbrush and spray a good epoxy primer all the way up to the hole.  Let it set up for 24 hours and then mount the base for your cap.

The thing here is you don't really need bare metal as you would with many other styles of caps.  With other caps you have a gasket of some sort in the cap and that gasket has to contact bare metal.  In your case you don't have that problem but what you do have is the possibility of an exposed edge.  You are certainly right that if its not sealed where gas fumes can get to it the paint will lift but it normally happens when there is a pathway between the coats of paint.  Epoxy primer is impervious to gas (but not acetone) and if you have it in direct contact with prepped (scratched and cleaned)  bare metal there should be no lifting.  So the gas/fumes should not be able to reach out to your gasketed area and if your actual paint begins on the outside half if it you should be well protected.

On Edit:  I just went back and looked close and hard at your photos.  You are more right than you thought, you need to take care of that before you fill the tank or its a sure thing that your paint will lift within a couple of weeks.  The way it is, painted all the way to the hole, its going to fail.

[Retro Rocket]

Epoxy primer is impervious to gas (but not acetone)

I think you mean "paint thinners" Kong. I use epoxy's every day mate and sometimes use acetone to clean an epoxy surface to clean it. Prep wash is acetone, it does absolutely nothing to epoxy once it has gone hard, actually unless soaked for a very long time, thinners does nothing either.  We always have a drum of acetone for clean up and never had one problem. I am talking about good quality epoxy, not cheap rubbish you may find in a hobby shop. I have used over 400 litres {20x 5gallon drums} over the last 12 weeks at one job and used acetone the whole time, we were painting the complete frame of a 100 meter + shed after a fire, acetone was used liberally to remove gunk off the structure. It may also depend on what acetone is used,  as prep wash is completely different to thinners which are both 100% hydrocarbons

[q2418130103p]

I knew when we painted it that we would have to sand it out.  I thought that a feather edge would be better than a masked edge.  I will go ahead and sand it to just beyond the screw holes.  Any ideas on something I can use other than epoxy primer, anything I can wipe on?  Its not really a big deal, I can spray on some epoxy primer, I just dont like spraying anything near something so freshly painted.


I think that before I send the tank out to have the liner removed I will at least do the sanding first, if not the coating as well.

[Retro Rocket]

I knew when we painted it that we would have to sand it out.  I thought that a feather edge would be better than a masked edge.  I will go ahead and sand it to just beyond the screw holes.  Any ideas on something I can use other than epoxy primer, anything I can wipe on?  Its not really a big deal, I can spray on some epoxy primer, I just dont like spraying anything near something so freshly painted.


I think that before I send the tank out to have the liner removed I will at least do the sanding first, if not the coating as well.

If its in a spray can just spray some into the spray can lid and use a small paint brush, doesn't matter if its sprayed or brushed on.....

[Kong]

RetroRocket,

Sorry about the misunderstanding, I'm not talking about an epoxy resin, I know acetone won't touch it (I used quite a bit of both myself), I'm talking about an epoxy primer.  Paint.  And yes, if you had some you could brush it on as well as spray it, but after all this is a custom paint job on a motorcycle, one should make some concessions for style.

Oh, I use PPG's Omni 170 epoxy primer.  Its available in black, white, or gray.  Its a straight up commercial body shop product, not too expensive and available all over the place.