85 300D Fuel Leak

Jul 29, 2006 5 Replies

I have a part that is leaking diesel on a 1985 300D (w123),



Here is a picture; the part is right off the fuel injector pump, arrows are pointing to the area that is leaking:

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It drips only when running, about 1-4 drops a second.



Can anyone tell me what this part is and how hard it would be to fix it?



That's the hand primer pump. It is used to pump fuel into the fuel system when one a) runs out of fuel or b) changes the fuel filters.

The round black plastic top unscrews to become the pump's handle for pumping. There's a rubber seal under the plastic top which fails and may leak.

Replacement hand pumps are available on-line for about $20; the replacement job is to unscrew the old pump and screw in the new one.

Your picture was worth the 1000 words!

Use the undersink basin wrench to remove it... from plumbing section of Home Depot/Lowes... used to remove faucet nut from the under sink.

Thanks for the feedback. I didn't realize that was a pump, I screwed that and gave it a couple of pumps and diesel squirts out the leaking spot real quick.

My pump handle looks white (or at least it was white back in '85) and has a slightly different shape then the ones I've seen on line such as:

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Would the Bosch black ones work? And just bolt right into place?

They always leak. Always.

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