123 Station Wagon/fuel screen in tank??

[Boston Benz]

I was just underneath my friends 1985 300TDT. I noticed that the in-tank fuel screen is very different from the 123 sedans. The sedans have the fuel line coming directly off the screen - it's very different in the wagons.

Does anyone know if it's just a screw-in screen used to catch particles with no fuel lines coming out of it? Or am I looking in the wrong place? I found the two fuel lines going into and out of the fuel tank but they don't pass through a screen filter back there. Very strange.

[dieseldiehard]

The lines goe up to different heights, the longer one is the fuel return (from the engine) and the shorter is fuel to the engine, which is located inside the filter which consists of a cylindrical shaped screen.
The base of the filter is what you see on the bottom of the fuel tank. It unscrews and comes straight out. Some use a large hex nut that fits, jammed by an adjacent nut on a bolt that can be used to unscrew the filter assy. The proper tool is of course a large hex key, you can grind down the nearest one in the inch size (I believe its close to 7/8 in) if you can't find a metric one, or the cheapest way is grasp the OD with channel-locks or similar pliers and loosen it then catch the fuel that runs out (better be near empty!)
The nice thing about the TD is you can remove the covers above the tank, (easier if you don't have the third seat) then remove the level sensor and look down into the tank. Good way to tell whether or not you have any algae.

[Boston Benz]

Thanks dieseldiehard for the response. I don't quite understand your first paragraph though. Are you referring to the translucent/transparent pre-filter by the hand primer pump?? The "cylindrical" piece inside that filter?? I think that's what you mean.

I still don't understand how that fuel tank screen works on a wagon if the fuel doesn't directly pass through it on its way to the other two filters...

A few weeks ago I removed and checked this screen in my 1980 300 TD. A search of my posts will tell the story. But here it is anyway: I removed the plug at the bottom of the tank using my biggest Allen wrench shimmed bigger with a flattened nail. It came out easily. I had prepared a plug: a golf ball wrapped in a sock inside a plastic bag. Jerked out the plug with screen attached and quickly put the golf ball up against the opening, losing a cup or so of fuel, which was mostly vegetable oil. This was caught in a plastic pan. Held the temporary plug in place with a 12-ton hydraulic jack. This worked just as planned, even with the tank nearly full. A much smaller jack would do just as well. Ha ha. Found the screen perfectly clean. Evidently the screen fits up through some sort of ring-shaped device where the intake line draws the fuel, making the fuel pass through the screen to enter the line toward the engine. With less fuel in the tank it would be a little easier to spill less fuel. Raising the front of the wagon would reduce loss more. The way I did it it really doesn't matter much how full the tank is.

[Boston Benz]

Thanks Knotman. Much clearer, now I understand how it works...

[P.E.Haiges]

Boston,

Easy way to check in-tank strainer is to remove the rubber fuel hose from the steel fuel line and observe how fast the fuel comes out. It should be a steady flow. If the flow seems slow, remove the fuel cap from the filler pipe and see if that makes any difference. If it does, the vent on the tank is plugged.

If the fuel is still slow after you remove the fuel cap, your screen is plugged and must be removed to be cleaned.

P E H