in december i bought a 1977 300d that probably sat for a while before being rejuvenated (wilson-phillips cassette under the seat). changed the fuel filters a couple of weeks ago, and primed large filter w/sea foam, resulting in a better running engine. decided to try some diesel clean in tank to keep things clean (after a post on another thread). the other day, it was running like crap, stalling out etc. i pulled over, lifted the hood and the 2 week old primary filter (clear one) was chock full of red gunk. fiddled around, pouring some gas in, shaking repositioned it, and it ran okay and got me home. went to the parts store (should have called first), they had to ship the filter from the local wharehouse. on the way home (4 mi), stalled gain, so in the wind and rain poured some diesel clean in filter, pumped to bleed, Naturally didn't have tools i needed, thank heaven for the small vise-grips i had). stalled a couple more times, finally wouldn't start, cranked the battery down, got towed the last 2 miles. went out with proper tools, pumped the air (hopefully enough), still won't start, as i went to bleed the air one more time, i noticed that a small diameter, rather short (9in), plastic hose hanging unattached from the sterno can shaped chamber on top of the fuel injector pump (probably pulled loose when i was wrestling with the filter). for the life of me, i cannot see an open fitting to pop the hose back on to. is this why it won't start? i can't get to the library to view the alldata website (which only goes back to 82 anyway) and have been unable to find the magic photo or diagram) this hose is the solitary hose hooking to the base of the sterno can. i am going to try pumping again, would appreciate helpful thoughts on my first time post, so i can get outa here. i guess the red junk in the filter means i may have to drain the tank?

Are you referring to the item in the (crappy) pic?
If so, that is the altitude adjusting box (ALDA) and there is not supposed to be a hose attached on that nipple, item #3. This should not be an issue.
You mention you have red gunk in the primary, clear inline, filter. This is an indication you have farm fuel in the tank, red diesel. It is taxed at a lower rate than the stuff you buy at the station.
You may have a clogged tank screen and/or a vent issue. The next time it stalls, or won't start, open the fuel cap, do you hear a whoosh? If so, you have a clogged vent. Try and locate an item similar to the one circled in the second pic, it may be near the left rear wheel.
You may be able to treat the fuel in the tank by adding a bio-cide, available at any marina, truck stop or on line.

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83 SD

84 CD

The OP said his pre filter was filled with red gunk....not reddish fuel.

I would suggest draining the tank at a minimum and cleaning the prefilter. It may also be wise to pull the tank entirely and clean it. blow out the fuel lines and make sure everything is clean. The fuel system is very simple. It just has to be clean and not leak.

Tank R&R is straight forward. Here is a link that may help.
http://dieselgiant.com/Mercedesfueltankremoval.htm

I have considered installing a couple "Y" fittings and have 2 of the prefilters in parrallel.

just a thought. I imagine that if the system is clean, that filter will last thousands of miles.

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83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

thanks, i heard a small woosh, so i am going to try clean screen. it did finally start, and also thanks for the info on the alda hose as well.

yeah, the tank may need drained, i'll check the screen. i picked up a few filters till i can get to the tank.

Said gunk is not known to be red which is why I mentioned farm fuel, usually it's (gunk) dark green to black in color. No other issues with using farm fuel tho.
A friend had a similar issue, the screen was clogged up enough to drip a few days, then when he removed it, a gallon or two came gushing out.

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83 SD

84 CD