1920 Cadillac Model 59 Vacuum Tank

[Guest Michael Patris]

Hello, I have a 1920 Cadillac seven passenger touring car, Model 59, with 60,000 original miles on it. It is complete other than the vacuum tank and brackets underneath the body. Does anyone know who made the tank and if there is a model or part number for it? I would like to locate one to add to the car.

Thanks, Michael Patris

[Bob McAnlis]

Michael:

Do you really mean the radiator overflow tank? My 17 model 55 had an overflow tank under the front floorboard. there was nothing to special about it. It had a fill spout on the top and a drain piping back to the radiator overflow on the bottom.

Unfortunately, I dont have this car anymore to be bale to send a photo.

Bob MCAnlis

Ohio

[Guest Michael Patris]

Hello Bob,

No, I do not mean a radiator overflow tank. There is an air outlet valve on the driver side of the car below the rear door and above the running board which, if opened and a tire pump hose attached, one could inflate tires with the car running while there is compressed air built up. I do not have the hose, but it looks like one would find on a tire pump. There are not too many 1920 models around, and, I do not know if this option was unique to the Model 59, but that is the deal. Now I am curious if there is supposed to be a radiator overflow tank!!!???!!!

Thanks so much, best wishes,

Michael

[sambarn]

The 1920 Cadillac does not have a pressurized coolant system, hence no overflow tank - just a pipe pointing at the ground. The car very well may have a vacuum tank fuel system - Stewart Warner had the rights to all vacuum tanks for a few years and likely is the maker for cadillacs vacuum tank, however they are usually located above the carb on the firewall so the gravity feed side of the tank can effectively deliver gas. There are aften on luxury cars of that era an engine driven air pump - usually from the water pump or generator drive pulley and a switch woulod engage the gear to drive from the shaft a small (6-9" X 2" - ish) air compressor. Perhaps this could be feeding air to the tank you describe but I've never seen a storage device to go with these pumps - usually just a hose long enough to reach each tire and a schraeder valve head.

[Guest Michael Patris]

Thanks for this info. I will see what else I can find out from my car (which is in the shop now, not at home where I can look at it). I was going on what I was told, which may or may not be correct... however, there is the air outlet and cap above the running board and below the rear door. I just do not know what is behind it. I was told it was a tank.

Thanks! Michael

[Rusty_OToole]

I'm no Cadillac expert but it is my understanding that Cadillacs in the twenties had a pressure system for fuel delivery.

There is a small air compressor attached to the transmission. This compressor pressurizes the gas tank to about 2 PSI. The compressor can also be used to fill your tires with air.

[Guest Michael Patris]

Thanks, Rusty! I think this is making more sense without my having the car at my disposal. The car does have a hand operated pump on the left side of the dash and steering wheel. However, that was bypassed before I got the car and an electric fuel pump was added. I wonder if the compressor going out had anything with the fuel pump being added, thus making the air not work? Hmmmm. Okay, now who made these compressors for Cadillac?? What do they look like and are they year specific???

Thanks again, Michael

[Rusty_OToole]

Look at the back of the engine or the front of the transmission. You should see a small finned cylinder. That is the air compressor. It is built into the transmission.

It was connected to the gas tank to pressurize it while under way. There was a hand pump on the dash to get started after filling the tank or when the car had been sitting for several days or weeks.

There was also an air hose in a tool box on the running board. This was used to pump up the tires. It could be connected to the pump through a door or hatch in the panel between the running board and body.

[Rusty_OToole]

Why did a previous owner change to an electric pump? Why does anybody do anything? He probably had a reason, or thought he did. What it was and whether it made sense, who knows?

[Guest 19caddylimo]

Hi there,

This may clarify a few things regarding your vacuum tank. I have a 1919 Cadillac. Although it's one year older than yours, this will apply to your car as well.

There is no vacuum (or air) tank on your car. However, your car originally had two air compressors on it. The first compressor is (or should be) on the transmission. Mine happens to be the "Kellogg" brand. It is used exclusively to provide a small amount of compressed air to the fitting you described on the side of the car for filling the tires. There is no air tank associated with this. The air line runs directly off of the compressor to that fitting.

The second compressor is on the engine. It's used to provide pressure to the fuel tank. It runs off of the front accessory drive and keeps the fuel tank pressurized so fuel can make its way into the carburetor. The hand pump on the dash is used to pressurize the tank, also. However, like described in the previous thread, the hand pump is needed to initially presssurize the tank prior to starting the engine. Once started, the air compressor on the engine takes over.

The car should also have a coolant overflow tank. It should be located on a bracket on the right frame rail just under the floorboard. Its only purpose is to keep coolant in the system and off the ground.

I hope this helps clarify a few things. Let me know if this was helpful.

[Rusty_OToole]

So Cadillacs had a total of 3 air pumps built in.