1971 Build for Dad

Here's how I'd proceed :twocents:. Cut a timber to fit in the tank saddle, run two straps around the tank, hook an air line to the petcock with a pressure regulator (not a valve), block fill cap, pressurize tank to about 10PSI, heat dented area with a heat gun, apply hot glue PDR tool, SLOWLY increase air pressure while simultaneously pulling with PDR tool.

The heat will soften the rubber tank liner and relax the metal. Applying pushing and pulling force will give you better chance of success. But remember to keep the air pressure low. You're not trying to blow the dent out with pressure just use it a helping hand.
 
Did some dent pulling this evening. Cautiously encouraged by the results. The biggest dent mostly came out in two pulls. Managed to squeeze a bit of an innertube in there that may or may not have helped and added some heat to it to get things loose. Hard to tell for sure, but the liner appeared to take it well.

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Hard to see in the picture once all the black is gone, but it is MUCH better. There is still an uneven area, but hopefully that can be filled without a pound of putty. While pouring over this I found another half dozen small dents - sounds like this is just par for the course... This is the most worrisome one after pulling:

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Moving forward, I figure I might as well and try to get it done. Aircraft remover and Bondo are relatively cheap, so no huge loss should it go down in flames. One question/opinion for you fine gentleman before I go any further:

When I was talking to the guy at Fuel Tank Services he recommended getting it down to bare metal (including rust removers), painting with a zinc chromate-based paint, then primer, and then starting on the body work with filler (duraglas). I had it in my head that filler was supposed to go one bare metal, but what the hell do I know? I have never done this before. I stitch genes together, not bodywork... :umm:

How would you do it?
 
When I was talking to the guy at Fuel Tank Services he recommended getting it down to bare metal (including rust removers), painting with a zinc chromate-based paint, then primer, and then starting on the body work with filler (duraglas).
When I was putzing in the garage with friends in the street rod and restoration hobby, I remember them doing it that way. The filler of choice was Evercoat. Zinc chromate went on first. I was never more than free labor pushing sandpaper, so take that with a grain of salt.

Rhy, is that the $15 Harbor Freight dent puller? I recently bought one, but haven't tried it. I watched some YouTube on it. A couple of users who had no concern for the paint, gained success using stronger glue.
 
Maybe you should give up lab work and pursue a career in motorcycle restoration.
Ha, sounds like a sound financial decision! I'm sure my wife would be supportive...

When I was putzing in the garage with friends in the street rod and restoration hobby, I remember them doing it that way. The filler of choice was Evercoat. Zinc chromate went on first. I was never more than free labor pushing sandpaper, so take that with a grain of salt.
Thanks for the feedback. Not totally sure what I am going to do here. I like the idea of zinc chromate, but about every video on YouTube shows filler going on bare metal. Going to do some more reading, might end up putting the zinc on after the filler, before primer.

is that the $15 Harbor Freight dent puller?
It was the HF puller. I thought it worked pretty good.. I cleaned all my surfaces with acetone and the glue held on past what I was expecting. I actually don't think stronger glue would have helped. What is left of the dents are either light creases or poorly defined dents that I don't think would come out with a puller.

Will keep you posted!
 
I’ve never put body filler over anything but bare metal... Buuuuttttt I’m just a joker in his garage screwing around.
 
............pressurize tank to about 10PSI, ..............
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Lets do a little math; tank circumference say about 40" around up and down inside the tunnel, by about 20" front to back so very round numbers 40x20 = 800 Sq inches, at 10 PSI that's 8 Thousand pounds of tank destroying pressure.
Do NOT ask why I know this. Lets just say I used to keep a gas tank picture tacked up on my shop wall. Even with the block and strap I think 2 or 3 psi is a lot in this situation.
In case someone gets inpatient with their heating method. I also have an unforgettable memory of a 30" jet of flame shooting up out of a gas tank neck followed by a large foomp and the the flame getting sucked in, deathly silence followed, finally, I started breathing again. Either inert gas or strong solvent rinse and LOTs of forced ventilation. You CANNOT water rinse a gas tank flame safe.
No idea how I've lived this long.
 
Lets do a little math; tank circumference say about 40" around up and down inside the tunnel, by about 20" front to back so very round numbers 40x20 = 800 Sq inches, at 10 PSI that's 8 Thousand pounds of tank destroying pressure.
Do NOT ask why I know this. Lets just say I used to keep a gas tank picture tacked up on my shop wall. Even with the block and strap I think 2 or 3 psi is a lot in this situation.
Gary's right be careful with the pressure. When I fixed automotive gas tanks I only used 2-3 lbs pressure. Much more than that they would try and turn into beach balls. Found out the hard way.
Either inert gas or strong solvent rinse and LOTs of forced ventilation. You CANNOT water rinse a gas tank flame safe.
I used a boil out tank to eat the gas out. Gas will get into the "pores" of the metal. Can be made safe with other methods.
 
I just looked up the filler over bare metal or primer discussion on Jalopy Journal. My conclusion is, I'm not going to try to paint anything. It's too complicated.
Well, my opinion, if that's allowed.... filler to metal gives you one bond or adhesive joint. Paint first, then filler gives you 2.... metal to paint and paint to filler. To my weird way of thinking, that doubles the chances of the filler debonding.... either by itself or the paint underneath. It's been my experience that polyester fillers (Bondo, Duraglass et al) stick extremely well to metal. I've never tried it over paint. The instructions on the can(s) say bare metal... and that's what we did at every body shop I ever worked at.
 
No idea how I've lived this long.
:laughing:

My conclusion is, I'm not going to try to paint anything. It's too complicated
I'm sure you have the right of it here. Hope you guys like :poo: shows, as I have one coming your way soon!

While I love the idea, I didn't pressurize the tank as I had this experiment in mind. I know it is vacuum, but same general idea of force and surface area...


Just put the aircraft remover on, no turning back now... :eek:
 
:laughing:


I'm sure you have the right of it here. Hope you guys like :poo: shows, as I have one coming your way soon!

While I love the idea, I didn't pressurize the tank as I had this experiment in mind. I know it is vacuum, but same general idea of force and surface area...


Just put the aircraft remover on, no turning back now... :eek:

That video was very cool!
 
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