CJ3A

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M-38 Fuel Tank Venting

Because the M-38 was designed to be ready for deep water fording at any time, fuel tank venting was not at the gas cap, as on civilian Jeeps. The M-38 gas cap was completely sealed. The M-38 incorporated a valve on the top of the fuel tank for venting. This one way valve was part of the fuel pickup/filter assembly mounting plate located on the top of the fuel tank. Photograph 1 shows a vent assembly as removed from the pickup/filter assembly. The bottom of the vent assembly was open to the interior of the fuel tank. A vent tube that terminated at the air filter was connected to the hexagon fitting on the check valve providing a connection to atmospheric pressure without the possibility of water ingestion when the vehicle was submerged during fording operations. See Illustration 1 "Fuel Tank Vent" line for the routing of this line on the vehicle. In Photograph 2 the vent assembly has been separated and the upper portion of the check valve is visible. There is a small spring here that holds the check valve up, this spring can be seen more clearly in Photograph 4. Photograph 3 shows the bottom of the check valve which incorporated a rubber disc seal. As fuel was being consumed by the vehicle this check valve assembly allowed air from the air filter to enter the fuel tank thereby preventing a vacuum from forming in the tank and causing fuel starvation.

Photograph 1

Photograph 2

Photograph 3

Photograph 4

Illustration 1

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