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Old 12-29-2005, 06:40 PM
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MB diesel filtration, how it works.

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.

Attached Thumbnails
MB diesel filtration, how it works.-mb-diesel-filteration.jpg  
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Old 12-29-2005, 07:05 PM
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Diesel filters, no tank strainers please.

Filters, Fungus, Biocide, etc.
Attached Thumbnails
MB diesel filtration, how it works.-dirty-strainerstg.jpg   MB diesel filtration, how it works.-clean-line-filter.jpg  

Last edited by whunter; 03-09-2011 at 01:49 AM.
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Old 12-29-2005, 08:11 PM
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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.
"If anyone knows other lessons I need to learn, please tell me. I'm tired of learning them the hard way".
by JerryBro

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
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Old 12-29-2005, 08:27 PM
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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!
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 84k - mine - (OC-85,500)
'17 Metris(VITO!) - 14k - wifes (OC-17k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'01 E320 - 179k - dad's (OC-182,500)
'07 E350 Wagon - 131k - dad's (OC-132,500)
'01 SL500 - 51k - dad's (OC-52,000)
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Old 02-03-2006, 02:59 PM
Join Date: May 2005
Location: CALIF
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Fuel Input Filters

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
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Old 02-04-2006, 05:39 AM
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Location: Lafayette Indiana
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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
[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.
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Old 06-12-2009, 01:10 PM
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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?
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Old 06-12-2009, 03:07 PM
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Nope, an air bubble is fine.
1991 350SDL. 230,000 miles (new motor @ 150,000).

2013 Fiat 500E. 20,000 miles, 80 miles at a time.
2012 Passat TDI. 95,000 miles. More space, power, and fuel economy than the Benz
2004 Touareg V10 TDI. 150,000 miles. One of 450.
1999 Jetta TDI. 310,000 miles.
1992 Jetta ECOdiesel. 156,000 miles. 1 of 48. Sold.
1991 Jetta ECOdiesel. 430,000 miles. 1 of 700. Sold to VeeDubTDI, totaled in front of our house
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Old 06-12-2009, 03:38 PM
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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?

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Old 06-12-2009, 03:58 PM
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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

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
AND use the Below pictured Water Separating Filter when refueling:
(Aircraft Spruce sold me the F15 [15GPM] at a very reasonable price.)
(I'm using it mainly on the Whaler's 160 Gallon Tank)
Attached Thumbnails
MB diesel filtration, how it works.-screenhunter_02-jun.-12-15.15.jpg   MB diesel filtration, how it works.-screenhunter_05-jun.-12-15.35.jpg  

'84 300SD sold

Last edited by compress ignite; 06-12-2009 at 04:36 PM.
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