VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1926 Vacuum tank

Anyone ever have issues with the vacuum tank? I have taken the top off and primed it. The float works fine but it does not pump. Any comments are appreciated.

I can think of a few things that might be the problem:

• Vacuum line to intake manifold leak
• Gas tank cap's vent hole plugged
• Gas line plugged
• Gas line filter (if there is one) plugged

After sitting for a few weeks, my vacuum tank occasionally needs to be primed. To help make this easier, I replaced an elbow with a tee on the inlet fitting on the top of the tank with a 1/8" NPT plug in the top that I can take out and pour some gas in.

Cheers, Dean

Vacuum tanks are very reliable if they are in good condition.

Not sure which vacuum tank you have. Most 1926 Chevys have a 8 screw Stewart. It has a die-cast top. If that is the one you have there are a few things to check. First there are two valves in the top. One that controls vacuum from the manifold. It has a brass seat that can come out. If it does it can be pushed back into place with either superglue or loctite to retain it. The other is a vent. There are also two springs on the "rocker" that must be present and functional. If all that is okay then check the bottom flapper valve on the bottom if the inner tank. If it doesn't seal then the pump will leak all the vacuum from the manifold and not draw in gasoline from the fuel tank.

Of course lack of vacuum to the pump, blocked gas line and any leaks past gaskets, etc. can reduce or prevent any gas flow from the fuel tank.

If you have another type vacuum tank then contact me via PM. I have rebuilt quite a few of them.

Thanks. I will check those items. It does have the eight screws.

Hey Chipper,
On the topic of Vacuum tanks. I had mine bead blasted and am ready to reseal it. Is there a special sealer that one should use or will any fuel tank sealer work? and do you seal both the inner and outer tanks?

Thanks

I suggest the best gas tank sealer you can find. With ethanol in gasoline today water is a problem. I had an inside tank eaten plum up by water. Looked more like a window screen than a metal tank. I coated it with urethane but haven't gotten the nerve to try it yet.

I got it off and the shut off valve is plugged solid. I can shake the tank without the top and insides and hear no flapper valve. The float and valves look ok inside. Does this tank come apart to get to the flapper valve. I tapped the top rim a couple of times but nothing moved. I do not want to break some thing.

a little shaking and tapping and mine seemed to come apart fairly easy, don't believe there is anything that you can harm. You might be able to slide a sharp object between the tops of the inside and outside canisters to pull the inside up out of the outside container.

There is a small inner tank that lifts out of the outer tank. With the top off, you should be able to see the lip of the inner tank as it sits around the top edge of the outer tank. Spray a little penetrating oil on this lip and gently pry it up with a super skinny flat screwdriver.

The flap is located at the bottom of the inner tank and will come out with that tank.

There have been many discussions previously about cleaning gas tanks and vacuum tanks and sealing them. But, you have to find that info. Enter the forum Search Function to the rescue!

One of the MANY benefits of joining the VCCA is the authorization to use the forum Search Function. Check this list out: Benefits of joining the VCCA

Cheers, Dean

Got it out. What a mess. Thanks for all your help.

As you now know you will not hear the flapper valve by shaking the tank. Hopefully you have the brass version and not the die-cast (white metal) one. It is best to test by taking it off and then sucking on it to see if it seals. Fairly hard to suck on the tank top to see if it seals. Been there done that before. I am slow but not dead yet.

If you have any questions or problems PM or email me. I have rebuilt a bunch of vacuum tanks so know most of the problems and fixes.

I used por15 gas tank sealer on my '25 Buick roadster over a year ago no problems. Looking for a vacuum leak was time consuming, finally put air pressure on the gas line at the vacuum tank and then found gas leaking at the top of the gas tank,gasket on the banjo connection.