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Steward vacuum tank trouble


Mpgp1999
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Hello

I have a steward vacuum tank and it no longer wants to suck gas from the gat tank to the engine. I believe the problem is in the lid. I tried to take all the fittings and gaskets and cleaned them to make a tighter fit but that didn't do anything. If I suck on the vacuum intake valve I can't get anything. Could it be the valves or has the pot metal finally given up the ghost.

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Have you checked to see if there is a blockage in the gas pipe from the tank to the vacuum tank  On the underside of the lid there are brass valves that are pressed into the pot metal lid Check to see if they havn't come loose Also check the seating of the flap valve on the base of the inner tank  Hope you get it sorted  Ron

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+1 to zeke01's comment.  Cracks in the pot metal head (lid) will compromise the vacuum.  I use a thin coat of black RTV on the TWO gaskets under lid (above and below the flange (lip) of the inner tank.  BTW, MOST Stewart vac tanks use the same 4.25" OD head, although fitting locations may vary--and that's irrespective of whether the reservoir portion is long and narrow or short and fat.

 

Other things to check:

 

The two valves under the head are (1) suction valve and (2) atmospheric valve.  The are connected by an overcentering lever with two springs.  The springs ensure that one valve is closed while the other is open.  New springs in stainless are available. Corrosion can also grow on the brass hinge pins. Best with a helper: Hold the lid upright with the float danging, then move the float up and down; check to see that the valves are snapping open and shut, as they should.  If they are hanging up, that's at least one of your problems.

 

Two things happen to the valves:  (1) they grow white "whiskers" (corrosion) which cause them to hang up--the corrosion can be removed with aerosol carb cleaner and a NYLON brush.  (2) the seats for these valves were originally staked (very gently!) into the pot metal and sometimes come loose.  You can re-stake (GENTLY!) or epoxy back into place.  If the latter, use a minimal amount of epoxy so as not to clog the valve.

 

Flapper at bottom of inner tank can accumulate gummy residue from gasoline, resulting in either (1) flapper doesn't close all the way, or (2) flapper is lightly "glued" shut.  Again, carb cleaner and a NYLON brush are your friends.  This fault seems to happen to me more frequently in the spring after about the first 10-20 miles after the car's winter nap.  Prevention is to drain vac tank before the winter nap.  I always carry a METAL pint can or two of fresh gas in a vac tank equipped car.  And a funnel!  Pour in one can, which can often remove the gummy residue.

 

If your reservoir has accumulated crusty deposits (the gummy residue turned hard), you need solvent PLUS abrasion.  I use methyl ethyl ketone (MEK) as the solvent, let it soak a couple of days, then use a wire wheel on a hand drill to remove the crusty residue.  Then I apply Metal-Prep or similar to the inside of the reservoir.  After that dries, I paint the inside with a thin coat of gas tank sealer.  Do this every 20 years!

 

My most recent malfunction turned out to be a clogged atmospheric (vent) passage between the atmo valve and the external vent tube, cleared by aerosol carb cleaner and shop air..

 

These tanks are simple and generally reliable, but they do need maintenance every 20 years or so.  If you google "Stewart vacuum tank" I think you'll find on the web a pdf of the original "owner's manual" showing the innards and giving instructions on troubleshooting.

 

Good luck and keep us posted.

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Try Romardb.com They rebuild vacuum tanks. Also sell gaskets, springs, etc. Join DB club and buy Stewart vacuum tank rebuild, reprints articles. Also, consider converting to an electric pump and regulator. Purists don't like it and if you have leaks with vacuum tank lines, fittings, etc. you will probably have them with an electric setup.

Paul

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With toms help took it apart and cleaned the whole tank and it no longer has any leaks. The gas line it self keeps getting clogged. It appears that there was a lining in there at some point and now that is coming loose. Along with rust and dirt

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good for you Matt. SO you learned two lessons today. How to fix a vacuum tank and NEVER put sealer in a gas tank. If the tank is rusty the liner will not stick and you wind up with the situation you have. The only real recourse is to get rid of the rust. That can be done with vinegar or molasses.  Shoot me an email I will give the instructions for either. I would go with molasses it's cheaper. Tom can get it for you when he feeds the mule.

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There is nothing wrong with tank sealer if its properly done.

POR15, which I have used on several occasions, with 100% success I might add, will work ONLY on tightly rusted surfaces.

Tight rust gives the solution a base to adhere to and cures to an incredibly strong film.

I wouldn't consider ANY of the other, so called, sealers because the ones I used didn't work........ :angry:

Edited by cahartley (see edit history)
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