Gas Tanks

1939-46 1/2 Ton Suburban/Panel Gas Tanks

Tuesday, November 29th, 2011


The gas tanks are totally different on the more common pickup versus the panel truck/suburban bodie, though the two frame rails, drive train, and front sheet metal are the same on each 1939-46 ½ ton.

On pickups the 18 gallon tank sets comfortably and safely within the seat riser and below the seat cushion. Over a million of these pickups were sold during this production period.

The panel truck and suburban were totally different animals. They had no protective seat riser. In fact, there was not even a passenger seat in most panel trucks. For protection, their 16 gallon gas tank was placed inside of the right frame rail and under the body. This gives the tank the safety of the frame rail and being in front of the rear axle. In the attached photos, the totally different shape is quite obvious.

In the following photos, the totally different shape of the panel truck and Suburban gas tank is quite obvious.

Gas tank removed from a 1941 panel truck.

1939-46 1/2 Ton Suburban/Panel Gas Tanks 1939-46 1/2 Ton Suburban/Panel Gas Tanks
1939-46 1/2 Ton Suburban/Panel Gas Tanks 1939-46 1/2 Ton Suburban/Panel Gas Tanks
Under the seat tank (usually on smaller trucks)

1937 to Early 1938 Chevrolet /GMC Gas Tank and Seat Cushions

Monday, August 22nd, 2011

So unusual to place a gas tank under the seat with no fill pipe outside the cab! To engineer this big change for 1937 was expensive and very different from earlier years when it was under the bed. Why was this done? What advantages could this have been over an outside fill spout? Was gasoline theft during the depression years a big problem?

To add gasoline on a 1937, the right lower cushion half was raised up toward the back which exposed the threaded ‘bung’ on the surface of the tank. It meant a person stood outside by the right side of the cab, raised the cushion half and added fuel. This is how it was done! If it was raining or snowing, the driver or the attendant stood there fueling. Maybe you kept an umbrella stored in this small cab for emergencies. Maybe gas station employees knew that when a 1937 Chevrolet or GMC truck drove in to get gas in the rain, a raincoat was needed. If some gasoline was spilled while filling, the vapor was smelled throughout the cab. If you were a cigarette smoker, well—–!!!

We were fortunate to recently obtain a set of 1937 original seat cushions. Even the upholstery on the two lower halves was still intact. The non-spout gas tank from the same truck came in the set.

Before they were requested by a serious collector, pictures had to be taken. Finding a pure set again in one place would probably be impossible.

An interesting feature is the plywood bottom on the right side removable cushion. The rectangular hole in the plywood prevented the springs from ever sagging and touching the electric gas sending unit. This must have been placed there to also protect the gas tank and bung from contact with a passenger’s weight on the seat. Engineers knew that a spark from an electric short near gas vapor would be a disaster!

We think these photos will be very interesting to the 1937 GM truck enthusiast. This way of tank filling continued into early 1938. Probably during the depression years, the manufacturer used their extra bodies and tanks that were left over from 1937 until supplies were depleted. Of course, this changeover would vary depending on the assembly plant.

The in- cab gas tank is also unique. It lies neatly inside the seat riser. The twist cap (bung) hole for adding fuel is at least 10′ away from the sending unit (protection from a gasoline pump add nozzle). For some reason the tank is built with two drain holes. One is always plugged and therefore the tank can be used in two type cabs. Maybe the gasoline outlet is different for right or left hand drive trucks!

Both Cushions have original upholstery Easily removable wood bottom half cushion. Note: the 2 small blocks to keep cushion secure on the seat riser.
Open spring half cushion for driver Both cushions raised above gas tank.
Plywood notch fits above gasoline sending unit. Sending unit in place.
Gasoline add bung and adjacent air vent. Open bung during refueling.
Top of tank. Note: Sending unit, bung, and air vent. Bottom of tank. Note: 2 Gas outlets.

Early Gas Tank Changes

Thursday, February 11th, 2010

During the three years of this cab design, subtle changes occurred as GM engineers learned better ways to construct this truck. The gas tank changes on the pickup body style was probably the most obvious and it was different each of the three years.

In 1936, the new mid year low cab pickup continued with the earlier practice of securing the tank under the bed and behind the rear axle. The gas add spout extended through a hole in the lower bed side behind the right rear fender. Thought it might seem like a good location, it was not. Considering the trucks stiff suspension the poor roads of the 1930′s, and how rough trucks were treated, this location resulted in tanks leaks and cracked fuel lines that were over 6 feet from the engine.

The answer to this problem came out in the 1937 trucks. The tank was moved to the protected area under the cab seat cushion. This solved prior problems but the improvement did not go far enough. The fuel add hole was in the top of the tank on the passenger side. To gain access to the threaded plug to add fuel, the right side of a new split bottom cushion was raised or removed. Rain or shine, the passenger would stand outside and wait for fueling so the seat cushion could be replaced. Of course, any accidental spills or splashing from the spout would give fumes within the cab till the evaporation was complete. What if you lit a cigarette out of habit? What about a small electrical short under the dash? Your imagination can tell you what probably happened a few times over the years.

The engineers seem to have got it together in mid 1938. They redesigned the 1937 tank and cab so that gasoline was added through a spout that now extended out the cab corner. The bottom seat cushion was then one piece, however, for several months two piece bottoms were still used on the assembly line until supplies were exhausted. Therefore, the late 1938 tank was used less than one year and is very rare today. The new designed 1939 body style continued with this type tank and cab design but the 39 tank will not interchange in the earlier cab.

early gas tank changes 1

1937 ( above)

early gas tank changes 2

1937 (above)

early gas tank changes 3

1937 (above)

early gas tank changes 4

1937 (above)

early gas tank changes 5

1938 (above)

early gas tank changes 6

1938 (above)

early gas tank changes 7

Gas Spout Hole from Outside

early gas tank changes 8

Gas Spout Hole from Inside

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