I'm working on a conversion of an '86 300E to make it into a 300D 2.5Turbo. I pulled the supply-side fitting out of the bottom of the fuel tank (I'm removing the electric fuel pump and associated fittings). The fitting in the bottom of the tank is a threaded specialty fitting of some sort. It doesn't match NPT, and it doesn't match a standard flare fitting either.

Can anyone tell me what the thread size&pitch is for this fuel outlet fitting located on the bottom of the tank for a W124?

I need to reduce the line size from the approximate 1/2" size of the existing supply line to the fuel pump down to regular 5/16" fuel line size.

SteveM.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

I don't have any cars here in front of me but are you refering to the fitting/hose combination that threads into the tank's fuel screen fitting?

Assuming that the 300E hose/fitting is not the same thread and pitch size as the hose/fittings used in most diesel cars (except TD obviously) maybe the best course of action would be to swap in a tank screen from a diesel car and use the regular smaller diameter diesel hose/fitting rather than fabricating something else. It would probably quicker and easier, assuming you've got some parts or parts cars at hand! Good luck!

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