Mercedes Benz selected a three stage diesel fuel filtration system.

#1. This is generally called a fuel tank strainer, but it is a filter.

#2. This is a disposable in-line particle filter.

#3. This is the final filter before the HEART of your diesel, the injection pump.

Filter #1 catches the largest particles.
Filter #2 stops medium particles.
Filter #3 does double duty, micron filtration, and a very small amount of water separation = measured in CC.

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1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

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Diesel filters, no tank strainers please.
http://www.peachparts.com/shopforum/diesel-discussion/140349-diesel-filters-no-tank-strainers-please-post1055081.html#post1055081

Filters, Fungus, Biocide, etc.
http://www.peachparts.com/shopforum/diesel-discussion/115952-filters-fungus-biocide-etc-post823378.html#post823378

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you might want to include the fact that the cannister's filter head is also an air bleed mechanisim that is tied to the return line.

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The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels

I was able to start my car today with only half of the spin on filled with fuel, it started, I rev'd it right away, about 3 seconds later it slowed way down and started missing and sputtering, but then it got going again and ran fine after that. Self priming!

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

1984 300d Turbo 137k
On The Rear Is Two Fuel Tank Rubber Lines, Tighten The Four Clamps 2 For Vent, 2 For Fuel, May Be Leaking Air In, My Power Is Ok Now,
Also Change All Fuel Rubber Lines In Engine And Injectors Fuel Returns Lines, Stop For Fuel Power Ok For 1/4 Mile Than Slow Again
Also Remove Egr Valve And Clean Use Carbon Cleaner May Be Sticking, Binding

those short lines in the back sometimes need changing. loose clamps there sets off a warning in my mind. i would take a close look at them and be sure they are sound.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I have a question. My primary filter appears to be half filled with air, the other half obviously diesel. The car runs and drives fine, but shouldn't it be full of fuel?

Nope, an air bubble is fine.

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

That is pretty interesting. Two questions come to mind:

1) if the injection pump acts as a filter, then should not you need to clean it out once in a while? Not done on my 81 300SD ever.

2) I have changed the in line filter - should be clear- but have never changed the one in the fuel tank since 1981. Have never had a problem. Does MB recommend that this one be changed on any periodic basis?

Thx

TYL604,

The Injection Pump does not act as a filter(If it ever has to,It's Too late AND you'll soon be buying a New or Used IP)
[Nor does the "Lift Pump" on the side of the Injection Pump]

The two filters in the EC (Engine Compartment) "Primary" (small,In Line type)
and "Secondary" ("Spin On") should be changed according to the OM [Or FSM]
(RULE of Thumb every 10 to 15 K miles.)

You only need to mess with the Tank Strainer if there are "FUNGUS" or rust
problems.

Sanity Disclaimer:
I tend to go kinda overboard on all kinds of Filtration...Filters (AND LUBE)Cheap ...IPs and Bearings Surfaces [Engines] are not!

I'm pulling the Fuel Tank and Making Sure there's NOTHING extraordinary in
there (Before I run the Almost New IP)
Replace ALL the Fuel Lines with Bio Compatible [fuel jobber went to 5% Bio
last month...No Choice...Although the 5% will enhance the Lubricity of ULSD]
I have this Great Big Honking Racor Water Separating Fuel Filter setup [90 GPH].
I'm going to "Graft" onto the MB filter head in place of the Factory
Secondary.
AND use the Below pictured Water Separating Filter when refueling:
http://www.mrfunnel.com/Mr._Funnel/Home.html
(Aircraft Spruce sold me the F15 [15GPM] at a very reasonable price.)
(I'm using it mainly on the Whaler's 160 Gallon Tank)

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