So; been running for about 1000 miles now on RUG/WVO blend in the '85 300D...with the 20 yr old fuel tank. Had to change 1 spin on and THREE primaries in this time. (When the filters are clean the car runs better than on diesel.)
Found out I have alot of microorganisms living for who knows how long in their stainless steel home behind my rear seat cushion. So got some bug killer called BioGuard and hoping for a 100% kill.
Drove 100miles last nite; taking my son to and from the Green Day concert in The Everglades; but this morning, she wouldn't start...Checked the primary, but it was fairly clean.....Got some advice, and checked the spin on;
Clogged 100% solid....iT WEIGHED ABOUT 1/2 LB. Could not blow air through it at all....(after a long day, or changing and cleaning filters and pumping the IP pump ..Had to ride my bicycle to the AP store, ) Finally at 11:30 PM pumped another 100 X and when the 2 yr old Interstate was down to it's final crank......PRRRUUUUUMMMMM!!!!
Starts up like it never missed a beat!!!!
Always have spare filters in the trunk. And hopefully the next primary will stay gunk free for 5000 miles....

__________________
'87 924S
'81 280SEL

Sold ->

81 300SD -
93 300E w/ 3.2
85 300D-
79 300SD
82 300CD
83 300CD - CA
87 190E 5 spd
87 Porsche 924S

"..I'll take a simple "C" to "G" and feel brand new about it..."

I had algae in my '83 Chevy K10 6.2 diesel tank, and ended up having to purge it, put on new filters, run with biocide, and ended up repeating the filter changes two more times before things quit being a pain. It's a lot more painful than on the mercedes. The secondary filter bolts on the rear of the intake manifold with hard to reach bolts. They are both spin ons, and I've since modified a filter wrench to allow me to remove the secondary without unbolting the housing. Now I try to always have a spare filter or two sitting around.
Ben

You're probably going to catch a few more of those dead bugs in the new spin-on filter before you get to 5000 miles. I'd change it at the slightest hesitation, or in another 1500 miles or so. See what it looks like and gauge the next change from there. I would also regularly add Redline (or other algae preventative) to keep this from becoming a problem again. I put 3 oz of Redline in with every fill-up. About every 2 months I give it a stronger shot, but I'm not sure it is needed. No algae. Injectors stay clean.

just my $.02,
Wes

Edit - and if the filter changes don't seem to solve the problem, you just might have to clean the filter in the bottom of the tank.

Did the '85 300D come with a SS fuel tank?
I have never seen anything other than plated steel in any of the 300Ds I have come across

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Oh. I don't know...I was just assuming.....

__________________
'87 924S
'81 280SEL

Sold ->

81 300SD -
93 300E w/ 3.2
85 300D-
79 300SD
82 300CD
83 300CD - CA
87 190E 5 spd
87 Porsche 924S

"..I'll take a simple "C" to "G" and feel brand new about it..."