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!
Tiger - 30 Jul 2006 04:42 GMT
Use the undersink basin wrench to remove it... from plumbing section of Home
Depot/Lowes... used to remove faucet nut from the under sink.
dozer - 31 Jul 2006 01:22 GMT
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:
http://replacement.carjunky.com/parts/carjunky/wizard.jsp?year=1985&make=MB&mode
l=300-DT-001&category=D&part=Primer%20Pump&dp=false
Would the Bosch black ones work? And just bolt right into place?
T.G. Lambach - 31 Jul 2006 04:55 GMT
https://www.autohausaz.com/search/productx.aspx?sid=ohdr1b45vsmgfe45vonceo2g&mak
eid=800016@Mercedes&modelid=1193790@300DT&year=1985&cid=22@Fuel%20%26%20Air%20Sy
stem&gid=6259@Diesel%20Primer%20Pump
Just screws into place.
Richard Sexton - 01 Aug 2006 10:25 GMT
>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.
They always leak. Always.

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