Finally after a long snowy winter I was done with all the deferred maintenance on my latest acquisition, a lightly driven 1984 300D wagon from wet Oregon.
Almost no rust of significance and 250K miles and an owner who did good engine maintenance. I did all the usual fixes that experienced users of this site well know from door hinges, stops, broken down seats, worn rubber/plastic components everywhere. Drivelines, brake system, front end. You name it. All new fluids and filters everywhere of course. I trailed the car 1000 miles to Wyoming. So it was finally test drive time. She started up instantly, idled smoothly and had lots of power............for about 5 or 10 minutes when she started to stumble and smoke a little and lost 90% of her power. I managed to limp home. It had to be fuel or air, since it was a diesel. All filters were new. I even added a secondary 2 micron Racor filter. I pulled out the plastic screen prefilter and saw a problem: it was VERY dark.
I pulled the new secondary Racor and it was black. The engine ran just barely and shook hard side to side with my new soft engine mounts. I removed the Racor and the engine ran better but still very rough at idle. I pulled the drain plug from the tank and the diesel was very dark , contaminated with algae. I did a little clean diesel flush and put in 5 gallons of new diesel. She started but still ran poorly on clean diesel. I rigged up a fuel polishing rig with an electric pump running through the Racor with a new filter with the engine off of course for 2 hours. The filter was a little dark.. I was afraid of pump or injector damage and feared the worst but I fired up the old girl with new filters again and crossed my fingers. For a minute she ran roughly and shook side to side and then suddenly stopped shaking and ran smoothly. A new test drive and she ran perfectly . It appears any permanent damage was averted and I hope a happy ending. This post is a cautionary tale for those of you buying a car from a rainy region. Algae contamination is unknown here is cold arid Wyoming.

That biomass is ALIVE! like mold & mildew it will come back if not killed. I use Biobor JF.

My '83 sat for years before I got it and the fuel tank & fuel level sender were caked with slime. Biobor worked well.

The "algae" diagnosis is unlikely to be accurate. Bacteria and fungi are generally the cause of microbial growth in diesel fuel.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Thank you. In Alaska we were always worried about Algae but it does appear that other microbes such as bacteria and fungi were the etiologic agents. Thank you for clearing that up I may edit the post to reflect that if I am able.

Thank you. We used Biobor constantly in Alaska on our commercial fishing boats. I was unable to purchase it here in Wyoming. I would like to add it to my tank if I can locate it somewhere.

Algae is a plant, and plants require light to grow.

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Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl,

The bacteria which causes problems in Diesel will only grow if there is water present. That water can come from condensate (at least theoretically) but often can come from a tank at the filling station. This can come from many places such as rain water getting into the tanks. Of course water will not work as fuel and when you get enough of it (not much needed) the car will stop running.

I once got a half tank of water in my 240d from a station.

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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.

Biocide will kill the bacteria and reduce it to a size small enough to pass through your filters. It does not take long either.

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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.

Biocide is available at truck stops and marinas.

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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.

My guess is that the green color seen in some contaminated fuel actually arises from Pseudomonas aeruginosa, which is a species of bacteria, and is one of the species of hydrocarbon utilizing microbes/microorganisms (HUM), nicknamed "humbugs" in the industry. I suspect the description "algae" used by some derives from the green color.

Killem is another good brand of Biocide. Look online. After biocide treatment of the contaminated fuel, further treatment with fuel conditioner containing enzymes is also a good idea. Starbrite is one brand. I know they are sold at boating supply stores. They will help break down the black asphaltenes which are produced by humbugs.

The asphalt can really clog the fuel strainer in the tank. I had a strainer that was probably 98% covered by this stuff a few years ago.

There are multiple threads on this forum regarding this subject. Good luck.

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Marshall Welch
Seattle, WA
1982 300D-T

Quite a few people on this forum have used Startron (for diesels). The enzyme it it is supposed to break whatever you call it that is in the tank into pieces small enough to pass through the filters. This reduces the number of filter changes you might have to do. And that would be a cost savings.

However, there has been at least 2 posts I have read of that their issue was bad enough even the Startron was overwhelmed.

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84 300D, 82 Volvo 244Gl Diesel

Quite a few people on this forum have used Startron (for diesels). The enzyme it it is supposed to break whatever you call it that is in the tank into pieces small enough to pass through the filters. This reduces the number of filter changes you might have to do. And that would be a cost savings.

However, there has been at least 2 posts I have read of that their issue was bad enough even the Startron was overwhelmed.

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84 300D, 82 Volvo 244Gl Diesel

After my experience of clogged filters in my Oregon TD I experienced a fuel gauge malfunction, sometimes shaking of the needle, sometimes reading zero so I removed the sensor and it had microbial debris thick enough to stop the float moving easily. After a careful cleaning, all is well again. I will look for the biocides recommended.

I've used Startron and have never had to drop a tank even though the car has had diesel that is several years old and sometimes has sat for a couple of years.

I haven't looked at whether the gas and diesel formulas are actually different. Gas is available locally. Most of the time I have to buy the diesel formula online.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

The enzyme fuel treatment is called Startron; Starbrite is the company that makes it.

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Marshall Welch
Seattle, WA
1982 300D-T