can someone show me where this thing is? i have looked to no avail. on my 92 300D it's on inline on the main fuel line.

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'92 300D 2.5
'99 E300TD

Put your finger on center of main fuel filter, 4"to left 10mm bolt holding pre-filter.

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

It’s beneath where the fuel line plugs into the top of the filter housing. It looks like a coffee filter or a pool strainer.

Don’t forget to renew the o-ring under the cap.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Sweet! I have the replacement and the oring, i just couldnt find it. I will look when i get home. Thanks for the help

Pro tip: park slightly nose down to help limit amount of air incursion.

Not too much or you’ll have a fountain.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

thanks for the tip! it will be ever so slightly downhill. should I hose clamp the tank lines under the hood? in my 300D 2.5, it took me a few times to realize that if I took the fuel cap off it released fuel system pressure, should I do the same?

__________________
'92 300D 2.5
'99 E300TD

Pinching the supply line would be helpful.

There should be no pressure on the fuel tank in an IDI engine, the fuel is sucked from the tank by the lift pump. The lift pump is capable of producing some serious vacuum, enough to collapse the tank if the vent is clogged.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Not exactly. The tank vent has a valve that allows 0 vacuum (to prevent tank collapse), but ~1PSI of pressure in the tank. That's the brief "whoosh" that's often mentioned when the tank cap is cracked. 1PSI doesn't seem like much, and it isn't, but it's enough to help push fuel through the fuel lines which is the intended purpose. The pressure comes from expansion of the fuel as it is heated in the fuel heater and from passing through the IP, and the resultant expansion of the air in the tank as the fuel warms up.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]