vacuum tank questions

[zeke01]

I have several vacuum tanks that I want to preserve or use. My question is: How do you deal with the rust in the inner tank and the inside of the outer tank? Evaporust looks like the best way to get rid of the rust, but the inner tank looks like it has been coated with something (tinned maybe). Will the Evaporust ruin that coating? At this point, does it matter? What do you coat the parts with afterward? I have been using gas tank sealant inside the vacuum tank to seal pin hole leaks and coat the tanks . This seems to work. What do you do? Zeke

[Hans1]

I have derusted then coated (painted) the insides with model airplane dope.

Even sealed some rust pits in oil pan,  not rusted through.  In addition I have sealed holes in crank case  oil filter screens.

some repairs are from the 1970's.

[PFitz]

Same sealers that you use for a gas tank.

 

I've been using the Bill Hirsch alcohol resistant gas tank sealer for gas and vac tanks since it came out about 20 years ago. Works very well with all brands of ethanol and e-free gasoline.  .

 

Paul

[Grimy]

I've found that removal of "varnish" (caked gasoline residue) within the outer tank (reservoir) requires mechanical abrasion as well as a suitable liquid solvent. For the solvent, I use MEK (methyl ethyl ketone), less than $20/gallon at hardware stores.  The MEK softens the varnish but abrasion is necessary to remove it.  Try clamping the reservoir to your bench and use a rotary wire brush on a hand-held electric drill.  I use Ospho or Metal-Prep on the inside of the reservoir to chemically kill any rust, then apply gas tank sealer with a paint brush.  Many of the float chambers were nickel plated at the factory to reduce corrosion.  I do NOT use tank sealer on the float chamber (interior can) for fear of inhibiting movement of the float,

 

The atmospheric valve and the suction valve on the underside of the lid/top/cover are connected by overcenter linkage and springs. Replace springs with stainless.  Clean the valves and seats with carb cleaner and a nylon brush to remove whiskery corrosion and be sure the seats are still staked in place in the fragile pot metal lid. 

[PFitz]

I've done dozens with the Hirsch sealer. If you let it fully dry to touch before assembly, not one problem with a float sticking. The fit of the floats in the top tanks are not tight enough to get hung up by dragging on the tank sides. Especially since the float and sealer stay wet with fuel.

 

The only thing to watch out for is that, with whatever is used as a sealer, the flapper valve and seat, and the top's vent hole through the tank flange need to be protected from sealer.  

 

Paul

[zeke01]

It was the plating that I was curious about. From the looks of the inner can there isn't much plating to be concerned about. I remove the flapper valve assembly when I coat my inner tank. It makes for a cleaner job. Zeke 

[46 woodie]

I would do as PFitz suggests and use the Bill Hirsch gas tank sealer. Pour it in slosh it around and let it dry and your good to go.

[PFitz]

1 hour ago, zeke01 said:

It was the plating that I was curious about. From the looks of the inner can there isn't much plating to be concerned about. I remove the flapper valve assembly when I coat my inner tank. It makes for a cleaner job. Zeke 

 

 

If you can unscrew a brass flapper valve assembly, like the Stewart Warner tanks,  that's good. But if you have to unpin just the flapper make sure to mask off the flapper valve seat also, or any sealer that gets on the valve seat will cause a vacuum leak that will pull gas from the carb line more easily  than it does from the longer line to the gas tank.

 

Paul.