Fuel Evaporation Valve and Fuel Odor

[Lew]

1971 280sl Continuing topic….  Gas odor in trunk and outside rear driver’s side (LHD).  I have replaced clamps and flex tubing at gas tank filler location.  Checked and verified vent tube from expansion tank to engine clear and functioning.  Have not yet replaced the 2 plastic hoses from the gas tank filler to the Expansion tank.  Need to know what the function of the tube that exits trunk floor below Tank Expansion Valve (115 4700293).  Additionally, how do I check proper operation of the Expansion Valve, and functionality of the fitting exiting the trunk floor?

[TJMart]

Lew,

My thoughts are that you have to trace all the lines to see if any cracks exist in the plastic lines.

You have two lines that connect at the fuel tank that you access from the tank curved cover inside the trunk. They go along the inside if the trunk and as you see in your picture go to the bottom of the expansion tank. you can access those from the two cover panels between the tail lights. The lines are plastic and crack with age so check those first since vapors escape through those lines into the trunk. you have a line at the top of the expansion tank that goes to the valve. The two lines that come from the bottom of the valve go through the trunk floor and through the rear wheel well. There is an access panel in the left rear wheel well. The hose then goes underneath the car and all the way to the front of the engine block.

Tony

 

[Shvegel]

The second hose that goes through the floor is a vent as well as the one that goes to the front of the engine.  If I recall correctly that one is there in case the pressure in the tank gets too high.  If memory serves the forward line should dead end under the car with the dot on the 3 way valve (Hockey puck) facing inboard.