Does anyone know the part no. for the oneway check valve that goes on the fuel tank on an 1984 300SD. This valve connect to the over flow pipe that goes to the top of the fuel tank. On the tank there is a metal pipe that is on the rear of the tank and exits the trunk on the drivers side, there is a short hose, then the 1 way check valve then another short piece of hose to another metal pipe. I need the part no. for the check valve mine broke while trying to remove the hoses so I could replace my fuel tank.

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Gary
OBK #37

That is the fuel tank pressure vent valve MB# 1234700225

1971 - 1985
Chassis Application:
W107, 022, 023, 024, 025, 026
W116.120
W123, 123, 130, 133, 150

Thank you, thank you, thank you.

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Gary
OBK #37

Question, is this check valve absolutely necessary?

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1981 300 SD 213k miles "Stock for now"
1999 Super Duty 7.3L 113k miles
1981 300 SD 180k miles "Heavily modified" SOLD

YES.
It prevents vacuum or pressure buildup that can damage the fuel tank...

But if the valve were removed and the vent line were open to the atmosphere, wouldn't the pressure within the tank always be equal to atmospheric pressure? I don't see how this would cause any problems but I'm, admittedly, not a physicist nor a mechanic.

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1983 300CDT -- 177K

The valve also helps reduce condensation + prevents insects from entering the vent tube/fuel tank.

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