My 1993 C250D just passed the 423.000km today and is still adding 1500-2800km per week. When I bought the car it had run 125.000km and I figured to drive the car till 500.000km...but that thought is changed by now; I am sure that I will drive the car till 6 or maybe even 700.000km.
A mercedes Diesel is a great car to drive and after it has been given the time to get to operating temperature, it can stand a LOT.
This C250D is even better as my former 190D (with 600.000km).

greetingz,

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1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)

Peter, Ken,
Thanks for the input. I had already tried the fuel filler cap, no vaccuum at any time regardless of speeds, etc. Now, what the heck is algae??? Like sea weed? How would it get in there?
Also, if something was plugging the fuel inlet, I'd lose power at speed when demand is greatest, right? Somehow this problem is tied to speed, because I can drive 50 mph all day and never experience it. But a few miles at 65+ and then it won't accelerate from idle and idles rough. It's really puzzling. It starts good cold, and idles great. But once it's hot and driven fast, it won't idle right until it cools down a few hours. And immediately after a high speed run, it needs to be shut off a few minutes or it won't go anywhere. But I can get right back on the highway and do 85 and it just loves it. I'm scared to take it to the dealer because everything is so ridiculously priced. I can see them trouble shooting this for a few hours and not finding the problem and a bill for $500. But is that my best option? Thanks for the quick replies.
-pyro

ps- I mistakenly said it has 450k- it's 250K!

Pyro:

The algae that grows in diesel fuel is like the green stuff that grows around the edge of ponds -- very tough and stringy. There are also several species of fungi that will grow in the tank, too, if there is any water in there. Huge problem with marine diesels, less common in automotive diesels but not unheard of.

I strongly suspect you have a partially plugged line or tank screen, and it aquires a vaccuum when you drive over 65 mph, collapsing the fuel lines (the rubber parts). Try GENTLY blowing compressed air (10-15 psi only, tank cap OFF or you will puff out the tank!) to clear whatever it is and see if that takes care of the problem.

Otherwise, you will have to get the tank cleaned.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,

You're the best! I finally had time to try compressed air through the fuel line. Immediately I noticed more power in town. Hit the highway, back to town, idles fine, although a little slow. (Haynes says I can't adjust the idle without special tools etc. True?)
NOW, how do I deal with this algae problem? Anything I can put in the tank to dissolve/prevent it? I assume this problem will return when whatever gets sucked into the sock and clogs it again. Should I still have the tank cleaned? Replaced? I'm also concerned because I fill up every third or fourth time from a furnace oil tank which sits outdoors and only gets filled about twice a year. This is the high sulphur stuff, which I understand to be better for lubricating things in the engine. (I also use that fuel all the time in a farm tractor, and have never had a problem. Of course the tractor tank is gravity feed to the IP, so I guess as long as I change the fuel filter it wouldn't be a problem.)
Anyway, I can't thank you enough for suggesting what I would never have believed or tried on my own. I love this car dearly and wish I could drive it forever.
-pyro

I put algaecide in my tank regularly as my pre filter was turning dark very quickly and needed changing often. You can buy it at Marine supply stores and probably at tractor and heavy equipment supply houses....
William Rogers.....

Pyro:

If your clog returns, get the tank cleaned. I'd plan to do it anyway when something else major comes up.

Cease and desist from using stagnant farm fuel -- that is a very good source for algae, dirt, rust, etc. Not all that good for the tractor, either! Keep it as fresh as you can, and keep the water off the bottom -- that is where the aglae grows. It is also illegal unless you are buying over-the-road fuel and paying the taxes!

Idle adjustment should be done by someone who knows how -- you can use the dash tach if you have one, but do not every exceed 1000 by much -- some governors can "run away" if set over 1500 rpm, and the only way to stop the engine will be to loosen the injector cap nuts. Not fun, and you will throw a rod on three cylinders out of four....!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,
The car may get stored for the winter months, so I'll probably pull the tank for cleaning before I get it out in the spring. I want to change the fuel lines too, as I suspect they may be cracked- the one at the prefilter was. I'm curious to hear the word 'stagnant' because I have always been told that diesel doesn't get bad the way gas does. And getting filled a couple times a year should keep it fresh enough.... There's a spin on filter on the pump, so I don't think rust/dirt are a problem, not sure about water though.
I pumped a gallon into a glass jug today and it looks fine, nothing settled out, etc. As for illegal, well, so is doing 75 mph or burning untaxed biodiesel, so most of us here are guilty somehow I suppose.
The idle is about 600 according to the dash tach, which seems a little slow/rough. If I nudge the pedal to about 800 it sounds much better. I've heard of diesels 'running wild' but never knew why it happened.
I'll try the algaecide for now. Does that work as a fuel drier too, or is there some sort of 'dry gas' especially for diesels?

Again, thanks for the great information. Beats Haynes all to hell. (Maybe you should be publishing your own How To manual?)
-pyro

An interesting side note to alge growing in diesel,I was talking to a fellow in the bar at the Anchorage airport some time ago,he told me he worked on a crew that x rayed the welds on the pipeline .He said that a number of welds had been eaten by bacteria that had been introduced into the crude oil from pumping sea water into wells that had lost there natural pressure.He said at first nobody could belive that any organizim could grow in 150 degree crude but there it was backing up behind welds and eating the steel.....

William alot of time we see what is called microbiologically induced corrosion. See it alot in stainless steel heat exchangers that use river water and run at around 150 dF+. It is actually the excretment from the organism (contains acids) that cause the problem and and it only shows up in the heat effected zones of the welded areas.

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Jim

Pyro:

Diesel fuel doesn't degrade like gasoline does (especially in contact with brass!), but it will collect water from condensation if the tank isn't full, and dirt from the breather. Nothing organic is completely inert, and no fuel is improved by sitting in contact with air. If the filter isn't a one micron filter, it isn't doing more than a paper towel would, either! I've examined engine failures on older equipment with 4 micron filters where the parts had a milimeter or so of clay on them -- ate the engine up in about 50 hours of operation.

Algicides are available at anyplace that services diesel equipment, algae is a world-wide problem (especially in the tropics). Fungus is, too!

Use RedLine or similar fuel treatments, they have some algicidal action, too, as well as some water absorbing ability.

The best way to handle water in diesel fuel is to drain it off -- change the filter regularly with spin-on models and drain the water off the others. If you add enough methanol or "gas line antifreeze" to dissovle the water in the diesel you will probably impair the lubricity and do some very expensive damage to your IP.

If the fuel is red, you a using off-road fuel and the fine is rather substantial -- not worth the added cost of road fuel. Besides, you are then also not paying your fair share for road building and maintenance (yes, it does take taxes, after all!) -- one mile of two-lane ashphalt paving cost upwards of $60000 these days......

600 rpm is a little low, unlock the rod that goes across the valve cover and lengthen it a bit. 800 is better with an automatic -- my 300D idles at 750.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,

How do I know what micron size the filter is? Been buying the bosch ones from benzshop parts dept.
It's strange, I've had diesel Rabbits, Jettas, Chevys, Volvos and Toyota trucks, as well as larger trucks, and have never had or heard of the algae problem! And I've run furnace grade diesel (from an outdoor tank) in all of them occasionally because I was always told it lubricated the pump better. (not to beat the tax! The actual road tax portion is about 10 cents per gallon here. My 10 gallons every couple of months isn't going to hurt revenues much... and I don't need to save a dollar that badly!)
SO...Is the Benz that much fussier than all those other diesels?
Or did I just get lucky for the last 20 years and never have an algae problem? Geez, one of the Toyotas sat for 2 years with the same 1/2 tank of fuel, and I started it up and drove it about 300 miles without a hitch!
Regarding the idle- there are two rods crossing the valve cover, a short one and a longer one going to the 'stop' linkage. Which one do I lengthen?
I found a 'dry gas' type product made for kerosene heaters, so I assume that would be safe in the engine? Not sure what's in it.
-pyro

Pyro:

MB filter will probably be 1 micron. Not usually listed on the filter. Older (1970's) US equipment often had/has 4 micro filters.

Algae requires water to grow -- it actually is in the water, not the fuel, but eats the fuel. No water, no algae, unless you get a fungus, much more common in the tropics. No common enough for everyone to be aware of it, but a serious problem in marine engines, salt or freshwater.

Furnace grade fuel is about the same as #2, usually IS #2 (or #1, bad news in hot weather). No difference in lubricity.

Yes, MB diesels are fussier. They also have a fine mesh screen in the tank and no external fuel bowl, standard feature on american equipment.

Just checked my manual -- idle speed is adjusted with a screw on the IP, can't help much as I've only done any adjusting on the old 220.

Rather than get all the dirt in the water into the fuel, I'd clean the tank rather than put gas dry in it. Most of the rust, crud, dust, etc, will be more likely to stick to the water -- remove the water, plug the fuel filters and screen....!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter-

Last week I was going out of town so I left the car at the local foreign shop to get the tank cleaned and idle adjusted. Idle adjustment was 2 hours, involves semi-removing the IP and #1 injector and doing a drip test, then adjusting IP timing up or down a few degrees. Got it up to 800 for me, but warned I may get pinging. How the hell am I gonna hear that???

Anyway, they said the fuel tank had a lot of stringy junk, and black crud in the baffled area by the intake sock. So they cleaned it and checked the lines, new filters, etc. For 2 days it ran fine, but tonite getting off the interstate after 1/2 hour at 65, it did the same thing. Chugged and stumbled at about 500 rpm. I had to rev it to keep from stalling. If it happens again I'll go back to the shop but just wondering if you had any thoughts on this. Thanks,

-pyro

Pyro:

I've never heard of setting the idle speed by adjusting the injection timing -- this is a separate issue. The most difficult thing is usually determining the actual speed of the engine, since most diesels don't have tachs. Yours does -- there is a screw on the side of the pump that sets idle speed, somewhere around the linkage.

I'm stumped as to the poor running at idle after a highway run at high speed. The only things I can think of are that the tank still isn't clean (and given the idle speed "adjustment" you got, maybe it isn't!), you got more dirty fuel, you valves need to be adjusted looser, or the seals in the IP pressure valve holders are leaking -- I'd be surprised since they are usually worse cold than hot.

Literally just had another thought -- does it knock hard, make black smoke and run poorly at low speed, but OK at higher rpm when this occurs? If so, you have a stuck injection timer! Its behind the vaccuum pump and advances the injection timing as the engine speeds up -- centrifugal thingy. If it get stuck at high speed, the timing won't come back down to normal low speed setting until it cools off.

Try blowing down the fuel line again -- if it is (temporarily) fixed again, you have junk in the lines, too, and will need to clean them or replace them (big pain, you must bend the line, MB doesn't supply it pre-bent!)

You can check the tank screen yourself -- the pickup/sending unit is under the first aid kit compartment in the rear shelf -- take out the screws in the bottom of the recess and it lifts out -- sending unit is directly below. Have a care not to drip fuel all over the inside of the car!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Great info. I was wondering I noticed such a change in engine performance after a long highway run. Even the following days are smoother.

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