1981 300D

Hi Guys,

I've been having to change the pre-filter very often and it gets clogged to the point it stops the engine.

I put another filter just before the pre-filter 2 days ago and it's clogged already.

I don't know what to do. I went to a boat store looking for some additive...and they want 26 bucks for a liter...and I'm supposed to put 1 oz. for every 16 gallons. That's an expensive option.

How about the diesel doctor offered by performance products? It is something I have to use every time I fill up the tank, or is it something to be used at certain mileage or time interval?

Thanks for any input...

Yep, I had the dreaded algae gremlin myself. My 300D was stored in a garage for about a year when I moved to Boston - had a full, fresh tank of untreated fuel when stored (I was not aware of algae problems in diesel fuel), it was started once a week, I drove it a bit during Christmas, then retrieved the car when I moved to Houston and drove it there from San Antone - on the same tank of fuel. The algae problems began almost immediately upon arrival in Houston.

Diesel Doctor should be the cure you need. Follow the directions for use (city driving is best after a dose so that the fuel sloshes around to soak the algae and dislodge it) along with extra fuel filters (both) that will need to be changed as the algae flushes through the fuel lines and clogs the filters. Then use Diesel Doctor all the time until all traces of algae are gone. Then, you will probably need to treat the fuel periodically with Diesel Doctor to keep the algae under control (it came back on me despite the fact I used Diesel Doctor for a while, did not have any algae, began using an additive to disperse water into the fuel, but the algae returned). I use it once a month.

The problem is the fuel pick-up in the W123 fuel tank is slightly above the bottom of the tank and water accumulates which becomes the initial breeding ground for algae.

Or, you can do what my local M-B dealer does: R&R fuel tank and send it out for chemical treatment then use sloshing compound to seal the interior, replace fuel sending unit, replace all filters including the filter screen in the fuel tank (a screen with large openings that Diesel Doctor should have no trouble dissolving the algae to pass through), replace all metal and rubber/plastic fuel lines, etc., etc. A very, very expensive procedure.

Good Luck!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

Where I work we just send the tank to the radiator shop and have the tank cleaned, no sloshing. We also replace the screen that screws in to the tank bottom.
I used to work at an airport. We had to use a product called Prist in the jet fuel (aviation kerosene) in the military helicopters we refueled on contract, it prevents the formation of algae also. I am unfamiliar with Diesel Doctor, if it is supposed to prevent algae, then it is probably worth the cost if the car sits around alot.
Gilly

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I'm considering a radical solution to this problem. I'm inquiring about a magnetic in-line filter used in marine applications. It's supposed to treat diesel fuel and get rid of most of its contaminants.

The smallest filter that they sell is a unit that will treat up to 25 gallons per hour for engines under 200 HP. The connectors are 1/4 inch. That seems to be a right fit for a MB diesel. This unit sells for $149 and it's supposed to be maintenance free. I think it's cheaper than removing and reconditioning the tank, fuel lines, etc, or pouring diesel doctor on a regular basis.

I'm waiting for their response. I'll keep everybody posted.

Dan:

Thanks for the info from your shop experiences. Diesel Doctor is recommended by M-B for treating algae problems - at least that is what the Diesel Doctor box says. As I recall, the techs at the M-B dealer may have sent the tanks to an aircraft repair facility that may have used chemicals more caustic than the radiator shop you sent tanks to. Hence, the reason why they had the tanks coated with sloshing compound. However, replacing all the fuel lines (metal and plastic), fuel sending unit, etc. seemed a bit much, but I guess they had their reasons ($$?).

Kefer:

One tube of Diesel Doctor costs $3.50 and treats 21-26 gallons, so a course of treatment is not very expensive compared to the time it takes to drain the tank, remove it, take it to and retrieve it from a facility that can clean it, and then reinstall it (although I will say the W123 tank is one of the easiest fuel tank to remove that I have come across). My problem took 4-5 tubes to correct and then a re-treat once a month. My two cents worth.

It will be interesting to read about the magnetic filter you are investigating and its ability to remove algae and other impurities.

Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

In the ads I've seen for Diesel Doctor, it looks like it comes in a squeeze tube like toothpaste. Is that correct? What kind of consistency product is it? Does it appear to dissolve/disperse OK in the diesel fuel in a standing car?

It's the toothpaste tube thing that's kept me from buying any. I don't want to squeeze paste into the tank.

Ken300D

Dumb question time; What causes algae? Is it only caused by the ingress of water into the fuel tank? I live in the rainy Pacific Northwest (north of Seattle) where it is raining constantly now, and I suspect that perhaps algae may be forming & gradually clogging things, and perhaps this could be the cause of my recent surging problems. Will algae form at any temperature? What can I do to prevent the formation of algae (other than driving a lot)?

I was going to ask a similar question ... how does algae get into the fuel and why diesel and not gas??

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... Kerry

126 tailed by a 203, 129 leading the pack.

Ken300D:

Diesel Doctor is a liquid, not a paste. As far as mixing with fuel goes, it is meant to be added when you are refueling. I add a bit at the beginning, a bit more at the mid point, and the rest 3/4 of the way through refilling to try and get an even mix. Then driving around town will more thoroughly mix it in as the fuel sloshes around in the fuel tank when making turns (the tech at Performance Products, when they were in Houston, told me that Diesel Doctor works best when driving around town so the fuel sloshes around soaking the algae and dislodging it and does not work nearly as well if doing highway driving - this is my experience as well).

Ducati:

It seems climates with high humidity are more prone to the algae problem. Where you live and where I live (San Antonio and Houston before) do have higher than average humidity levels which will cause greater condensation in fuel tanks, esp. when the temp. varies a lot. Much less the very real chance of getting water and/or algae contaminated fuel when you fill up. Diesel fuel is different than gas, as diesel has more organic compounds in it that when water is also present will promote the growth of algae (use the search function to find past discussions by members with more knowledge of the scientific basis for this problem). I do not have any specific knowledge about temp and its affect on algae growth, but I am sure it is warm enough in the NW so that it will form in your fuel tank - use the search function to see if this particular issue has been written about by others.

You can see the larger pieces of algae in your in-line fuel filter as grayish/blackish colored flecks/chunks (if it is the clear type, a flashlight shined through the opaque type filter will show the mess, but not as well). The finer particles will pass through the in-line filter and clog the large spin on fuel filter (that looks like a small spin-on oil filter).

If you have algae already, then you must treat it with Diesel Doctor or remove the fuel tank and have it chemically cleaned, etc., etc. Driving won't help, as far as I know - unless you mean keeping the fuel tank full or nearly so to cut down on condensation. However, keeping the fuel tank full if you already have algae does not seem to be a solution. I try to avoid fueling when it is raining or when the humidity is very high, however, this is not always possible. Unless you mean that driving the car often will keep the water in the fuel tank mixed with the diesel and then the water is run through the fuel system into the combustion chambers - this makes some sense as my initial algae problem only happened when I let my 300D sit for an extended period.

A surging problem could be linked to algae clogging the fuel system causing less fuel to reach the injector nozzles resulting in a less fuel available for ignition when the air is compressed by the piston (a lean condition). Algae can stop the flow of fuel completely and then stop the engine. However, surging can be caused by other problems. I would look at the algae problem first and eliminate it, and then move on to other possible causes for your surging problem - and a new post to reach myself or other members who can help you.

Hope this helps!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

Interesting info. on fuel microbes and their apparent increase particularly in the NW. http://www.pfs-pros.com/page15.html

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Interesting read. More on ...

". These bugs feed on the oil in the fuel and use the water in the fuel for their oxygen supply. They grow in your fuel at different rates and can easily cost thousands of dollars in damage to each contaminated vehicle. The spread of this problem is alarming considering that you can contaminate a clean system just by using a fuel nozzle that has been in a contaminated tank ... ".

Thanks.

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... Kerry

126 tailed by a 203, 129 leading the pack.

http://www.rjkpower.com/pri.htm

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1999 E300 TurboDiesel
2007 Ford Explorer limited
1981 John Deere 650 Diesel tractor

jbaj700 and richard u:

Great info and links about the problem of gremlins growing in fuel causing lots of problems - Thanks!!

This info mirrors and greatly expands on the info I read 4-5 years ago about algae and other contaminants (when my algae problem first reared its ugly head). With more time the problems have been researched more thoroughly and solutions to cure the problems (the EPS regs went into effect in 1994, as I recall, for low sulfur diesel).

Algae, evidently, has been a problem before the new EPA regs to lower sulfur content in diesel fuel shown by the fact that Diesel Doctor was used for a while before the regs took effect.

Most interesting that the contamination can be picked-up from a very small amount transmitted from an infected vehicle through the fuel fill-up nozzle. This could explain why my problem returned over 4 years after fixing my initial algae infestation - with no evidence of algae contamination during this time as I monitored my in-line fuel filter for algae and the tell-tale discoloration of the fuel itself, esp. when the fuel level is low and, hence, a higher exposure to the area where the algae would be more prolific/concentrated. This fact reinforces my use of Diesel Doctor once a month to keep the algae gremlin away and why the use of a water dispersent additive is not enough (as I did following my first algae infestation)!

Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

Not that I feel for those who are having problems, but is seems funny how our rugged cast iron machines can catch a living, biological " virus" from another car and be imobilized by it.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

I wonder if a water separator hooked up in line from the fuel tank would help keep algae oe other fuel related problems at bay. I have seen water separators used on big highway tractors & wonder if such a device is available for our diesels & if it would be benificial, especially to those of us who live in rainy climates?