Thanks, PEH and phantoms,

I've read the posts on the fuel strainer, but I didn't see anywhere the size socket wrench needed to remove the strainer on a Mercedes '84 SD300. I think it has to be a socket wrench owing to the small space I have to work where it comes out of the tank.

I am about to do the test you suggested to see how much fuel comes out of the line when it is taken off the strainer, but I am almost positive it is plugged with fungus, since I just replaced my filter and prefilter and still had power loss. I had used biobor a few weeks ago. It helped, but the problem came back. Added doses of biobor didn't help, but it may be because I refueled before adding the biobor and it didn't mix well. I am now trying to get my tank level down in case I need to empty it, so I don't want to put more fuel in again, so added doses of biobor don't seem to be helping because they may not be mixing.

In any case, I am prepared to remove and clean the strainer - I plan to either siphon or drain my half tank of diesel. All I need is the wrench size (the 1 1/4 inch one I bought is too small).

DannyF,

Biobor will not clean the fungus out of the system, It just kills what fungus is in there so it doesn't continue growing. By the amount of Biobor you said you added, I'm sure all your fungus is dead, but still in the fuel system.

Your filters will get the dead fungus out of your fuel system, but you can expect to change them several times, especially the inline filter. I guess I was lucky, my inline filted plugged only once in my '80 300SD in over 10,000 miles since I added Biobor. So I figure all the dead fungus is gone by now.

Maybe I was lucky but I was able to remove the tank strainer by turning the 17mm or 19 mm nut on the fuel line connection to the strainer plug. Give that a try first as it is the easiest way and you don't need a special wrench. I don't see how it is possible to use a socket wrench to remove the strainer plug, if I remember correctly.

I cleaned the strainer by blowing the fungus out with compressed air. The dead fungus is like brown silicon rubber and I couldn't find anything that would dissolve it.

P E H

I wanted to do the same thing on the SDL. However, due to the slighly recessed position of the strainer, nothing but the actual socket would do the job.

The size is 46mm. A 1 13/16 socket will also work fine. The SDL had clearance problems and a socket that large (with 3/4 drive) would probably be too long for it.

I understand that the proper tool is a special, short, 46 mm socket with a 1/2" drive.

A wrench that large may also not be suitable due to limited room to swing it.

Good luck. If you do get it out via an alternate method, please advise.

My prefilter would turn BLACK after less than a half-tank, so I took action.

I drained the tank, when I removed the hose from the bottom of the tank, the fuel GUSHED out, so the in-tank strainer is not clogged (or it has been compromised in some fashion) anyway, I filtered all of the fuel, and got lots of black gunk out.

I now have 2 primary filters in the fuel line, and I have been reusing the prefilters. I can't believe all the gunk that comes out of that tiny filter.

Am I the only one here cheap enough re use the primary filters?? I just rinse with simple green, gently blow it out and reinstall. (then 100 miles later its jet black again.)

I'm using a star-brite fungus enzyme, (the same one I use in my boat diesel) hopefully its doing its job.

Cheers,
Robert

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Cheers,
Robert

Hello Mister Byrnzoil and thanks to PEH and Brian C. for your comments.

In response to Mr. B.: I am not that experienced working on these cars yet, but your experience sounds similar to mine. Fuel gushed out of my line after the strainer, too. I stopped it back up because I have so much in the tank and I didn't want it all out at that point! I siphoned a bunch (7 gallons or so) of the diesel out through the fuel tank. That stuff looks real clean. The stuff that gushed out of the fuel line that I caught in my basin was black. I think I can re-use the stuff that I siphoned out (I'll treat it w/ biobor to keep it clean).

With less fuel in the tank, maybe it will gush out less quickly, so I'll probably siphon some more out and then attempt to remove the strainer and catch what comes out at that point. My intention is to re-use this strainer (from what I read on this conference, cleaning it and then reusing it is fine). I am less tempted to re-use the prefilter, but I cannot comment on that. The prefilters are cheap, though, and easy to get....

Brian and others, I did end up draining the tank now that I have ramps that allow me more space to work under the car. I have about 12 gallons of biodiesel in containers. It looks pretty clean, surprising considering how gummed I thought the fuel strainer would be. I am encountering the problems you listed, Brian, to get the fuel strainer out. Lack of space to work.... I ended up buying a 46 mm socket with the 3/4 inch drive (that 'special 46 mm tool' would have been ideal..). I tried using a screwdriver in the hole in the socket wrench to give me a lever arm - the screwdriver bends, not enough torque.... Not enough space to use the 3/4 inch drive, so I am trying to see if I can get a good enough grip on it with an oil filter wrench that can hold the 2.5 inch (outer diameter) socket. I'm still on it. Removing the fuel line, as suggested above, didn't help with trying to get the fuel filter out... One neighbor suggested having my 46 mm socket cut shorter so that with the 3/4 inch driver it would fit in the small space.... Where do you get the special short 46 mm socket wrench? (now that I bought the standard wide one....)

I also tried removing the return line to the tank to allow me more room to swing wrenches and such for the fuel strainer. I can't even get that 3/4 inch or so nut off that hooks the return line into the tank.... It seems I am about to tear into the tank itself to get that nut off.... Is there a good way to get the 3/4 nut off (they have several inch hoses attached) when there is a ridge present that keeps from getting a good grip on the bolt with a crescent wrench?

Heck, now that I have gotten it this far, maybe I should just remove the whole tank so I can get the strainer off and give the tank a proper cleaning....

Why Bother.
Swap the "fuel delivery" and "return" lines in the engine bay and draw fuel from the "return" line and return fuel to the tank in the "fuel delivery" line. Any contaminants in the tank which are picked up will be deposited in the prefilter. The "return" line goes to the bottom of the fuel tank (in the sedan at least).
Assuming the same design brief for the designers of both fuel tanks, the wagon should go there too.
My wife's car has been running in this configuration for 12 months now, since it has a "one-way" issue in the fuel lines. - Fuel will go into the tank from the "fuel delivery" line, but not from the tank in that line. I even replaced the fuel tank, with no resolution of the problem. Remove the flex hose from the strainer and fuel flows freely, no dings in the metal fuel line, just one-way flow. Swap delivery & return, NO PROBLEM.

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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.

Yep, been down that whole road. Never did pull the strainer due to lack of proper 46 mm socket. I think it might be a dealer item, but, I'm not positive.

Both my supply and return hoses are right next to each other and both are held with those brass 3/4" (something metric) nuts.

What is the exact issue with removing them? The stick down far enough from the tank so that you can get an open end wrench on them. I'm not sure of what you mean by a "ridge present" that keeps you from getting a good grip on the bolt????

Same setup as mine. The 'ridge' is this 1/16 to 1/8 inch wide piece of metal that seems to be part of the tank that surrounds the fuel filter/return hose region. It is one of the things limiting my access, but isn't the only obstruction. I did manage to remove the bolt going into the fuel strainer - the other one is just real stubborn and my 3/4 inch wrench isn't able to get a torque in quite the right direction to remove the nut (partly because of the ridge). When I do get a pretty good grip the bolt seems to start to turn in a funny direction that speaks of the socket holding it giving way. I just don't trust the strength of the tank near this bolt. Maybe I can leave the return line alone if I can get the fuel strainer out.... I'll keep playing and see what happens.

Ridge? This ridge you mention sounds a lot like the fuel screen itself. The fuel line screws directly into the bottom of the fuel screen. The bottom of the fuel screen is a light weight "nut" made into a flange that is 46mm. I had no problems on an '84SD with a 3/4 dr. 46mm socket on about a 10" ext. (Harbor Freight special). I'm not understanding the problem you are having.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I've done quite a few strainers, both on my back in a driveway and on a lift. Some are just easier than others to bust loose, if its getting replaced, try knocking it loose with a hammer and chisel first, the 46mm socket can be hard to keep on the nut while applying torque. I usually use the 46mm socket, 1/2" swivel and 2ft 1/2" extension on a breaker bar.

Who has a cheap source for the socket?? I really need to buy one of my own ....or SAE equivalent?

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

What I am calling the ridge seems to be a small protrusion of the fuel tank itself. It surrounds the 46 mm fuels strainer flange and the return line nut and the ridge is just the right size such that it allows the 46 mm socket to fit around the flange. I'm sure its not called a "ridge" officially, its just my lay person's name for it. This ridge is not a big deal, but it keeps me from being able to put a crescent wrench flush onto the return line nut that I am trying to turn. These nuts are so stubborn that every little thing that gets in the way just makes it harder to get the nut off. I will try again when I have some daylight time at home... I wish I could use your 10" ext. Harbor Freight Special because the one I bought doesn't have clearance with the 46 mm socket I have, so I am resorting to other means.

Thanks, everyone, for your input.

I need to take out my fuel screen but can't find the proper tool.

Went to five garages in the Biloxi area and no one has one that large. Have been on phone and computer for days looking.

Thanks for your help.

I used a cheap Harbor Freight 3/4" drive socket set. I believe it was about $50.

This may work:http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=6970&productId=200322603&R=200322603
Or this:http://www.shop.com/op/~17_Pc_Jumbo_Crowfoot_Wrench_Set_Metric_20mm_to_46mm-prod-15500666
Or if you already have a 1/2" drive socket set:http://www.shop.com/op/~46mm_Front_Wheel_Bearing_Retainer_Socket_1_2_Drive_Impact-prod-15505972

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Sam

84 300SD 350K+ miles ( Blue Belle )

I find it funny that there is no special Mercedes tool for this purpose that retails for about $119.95.
Usually such is the case.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)