Overview: this upgrade addresses the concern some have over the absence of a fuel/water separator in 123s, and adds an excellent pre-filter that should increase both the final filter’s efficiency and life.

Top View (install details follow):


Parts:
Stanadyne FM100 30 micron pre-filter water seperator assembly (3/8" NPT ports)
go to www.reliableindustries.com or call 800-693-4583, order part#33641 - LINK for a measely $32.68

other parts you'll need:

• ~4' 5/16 fuel hose
• 2 hose clamps
• brass fittings: 2x - bushings 3/8 to 1/8, 2x - 3/8 plugs, 2x - 1/8 street elbows, 2x - 1/8 to 5/16 hose
• teflon tape
• stainless steel mounting hardware: 2x - 5/16x1-1/4" bolts, 4x - flat washers, 2x - 5/16 nuts, 2x - 5/16 self-locking nuts

the install:
1. assemble all brass fittings on the filter head.

2. attach the short section of hose to the intake and the in-line pre-filter

3. mount filter
drill 2 5/16" holes
insert 1-1/4 bolts from the back, put a little permanent locktite (red) on the first 1/4 inch of exposed threads, then tighten down nuts over the locktite against the sheetmetal (this creates your filter mounting posts), then add flat washers, filter head, flat washers, self-locking nuts



4. attach remaining fuel hoses

5. pre-fill FM100 with a good fuel additive (unscrew large black filter assembly cap by hand and pour additive in).

6. prime system with OEM hand pump

7. drive - you're done!

additional images:


in-line's already catching crud:


Clear Bowl Water Reservior Option:
you can see in the pics that i have an additional clear bowl water reservior installed. this is an easy screw-on option - part#29899 $26.96 from reliable. i happened to have this one already, so i installed it but it's hard to view so i will probably leave it off when i replace the filter.

FM100 water removal efficiency:

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Current Vehicles: 2001 Mercedes E320 Wagon | 1979 Mercedes 220D | 1995 Volvo 850 Turbo Wagon | 1993 Volvo 240 Wagon

Very nice install!
Any idea what the filter elemnts cost?

thanks!

the 4.3" element that comes with the assembly is part#31865 - $11.17
a 6.0" replacement element is part#31869 - $13.06.

i will probably go with the 6.0" when i replace the filter since it should last even longer.

FWIW - i have a FM100 installed as the final filter on my VW TDI and did this writeup:
http://forums.tdiclub.com/showthread.php?p=1121994

cheers!

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Current Vehicles: 2001 Mercedes E320 Wagon | 1979 Mercedes 220D | 1995 Volvo 850 Turbo Wagon | 1993 Volvo 240 Wagon

Nice install. Thanks for posting! Are you going to put in the drag-pointer restriction gauge on your 123, too, like on your VW? And if so, please post up your WOT restriction numbers so we can all be lazy.

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Currently converting a 1984 Toyota Land Cruiser FJ60 to use a 1985 300D engine and tranny... Engine/tranny are in, no transfer case or wiring yet.

Nice! Too bad that corner of my bay is so cluttered already....

Thanks! I'm not going to install drag-pointer restriction gauge on my MB just because the MB filter (30-micron) should have much less restriction than the VW (5-micron) and the fuel flow rate on the MB is much less than the VW. The VW uses less fuel of course, but it relies more heavily on fuel to cool the injection system - so in the VW fuel that's not injected passes through a fuel cooler and returns to the tank at a relatively fast flow rate (compared to the MB).

And, if you go with the 6" replacement filter restriction will be even less...

Cheers!

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Current Vehicles: 2001 Mercedes E320 Wagon | 1979 Mercedes 220D | 1995 Volvo 850 Turbo Wagon | 1993 Volvo 240 Wagon

Does anyone know the filtration micron size of the stock MB filter(s)?

R, nice pictures and write-up !! Why is there so much crud in that pre-filter?? Did that car sit a long time?

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1998 W210 diesel (wiped out by a texter)
Baum spring compressor "for rent"

Doesn't the filter on VW diesels have a water separator built-in? It probably wouldn't be as stout as the setup you installed but would probably be a lot cheaper to just grab the filter assembly from an old diesel VW.

Edit: Just read this:
So I guess the VW one isn't sufficient.

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

yes, the 123 final filter (spin on) = >20% at 5 microns:



yes, i purchased it from a guy that wasn't using it anymore. the revitalization has begun! i'm going to drain the tank and replace the tank strainer the next time the fuel guage gets down near E.

the FM100 replaced the OEM filter in my TDI - and i added an MB in-line pre-filter to the VW setup.

stock A4 VW TDI fuel filters do have a water seperator, BUT, the filtration efficiency is no where near as good as a FM100 5-micron. for example: OEM = 58% at 3-5 micron; FM100 5-micron: 92% at 2-micron, 95% at 5-micron, 95%+ of emusified water and 98% of free water.

replacing the FM100 (~$14) elements is cheaper (and much easier) than replacing VW A4 OEM filters ($29).

cheers!

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Current Vehicles: 2001 Mercedes E320 Wagon | 1979 Mercedes 220D | 1995 Volvo 850 Turbo Wagon | 1993 Volvo 240 Wagon

I am very curious to see how much water you capture. I'll be checking in with you periodically

Excellent! I’ll add that to my list of things to do.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

FWIW - which fuel additive you use (if any) can have a great effect on whether you can capture and drain off any water. If you use no additives you're probably going to be able to capture and drain off water. Stanadyne Performance Formula is one of the few additives that will enhance your fuel filter's ability to remove water. Most other additives will increase the fuel's ability to hold water in a micro-emulsion that can safely pass through your fuel system.

Here's some interesting reading regarding the type of micro-emulsion that Total/Elf, Primrose and FPPF additives use:

this sounds scary - i don't think i want to know the details...

FWIW - i have a CAT fluids analysis lab just down the road from both my home and office. oil analysis can help you determine and take actions to minimize engine wear. providing your engine with clean fuel and clean air greatly enhances your oils ability to perform optimally - and do so for an entire extended drain interval. this of course results in better performing, longer wearing engines. knowing this, i never take shortcuts regarding fuel and air filtration. [re: clean air, i recently discovered that the Hengst air filters have probably double the filtration area (twice as many pleats) as the Purolator 123 filter available at my local auto parts chain.]

cheers!

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Current Vehicles: 2001 Mercedes E320 Wagon | 1979 Mercedes 220D | 1995 Volvo 850 Turbo Wagon | 1993 Volvo 240 Wagon

Very interesting, I've been wondering about options for water separation systems. Thanks for the great writeup. Once I've got the 300D back on the road, I'd love to catch up and take a look at what you've got.

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1987 Mercedes 300D

Nice setup.. I might have to buy that as a Christmas gift to the Mercedes.

so far the car is getting about 80% of my christmas wish list

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