JUST the day after I filled up last week with my usual 20% bio, 80% USLD mix I returned to find a fuel puddle directly under my tank. After climbing under for a closer look, I noticed the short sections of rubber lines that connect to the supply & return metal lines that run under the car are wet & weepy. Not sure, but there also seems to be some leakiness from what looks like a drain plug at the bottom of the tank itself (is there a gasket in there?)

Logically, this doesn't seem like a fun job to repair. I'm guessing the now almost-full fuel tank has to be drained, or fuel will run out like mad when changing the lines. Or is there a trick to this?

I don't know when the rubber lines there were last replaced, so it might be normal failure, but I can't help thinking the biodiesel contributed to the deterioration of the rubber. Is it necessary, or desirable, to get Viton lines for this, and where would I get them? I didn't use Viton for any of the under-hood lines and they are still fine after several years of B20 use (but maybe not much longer!)

-AC

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1976 240D "Katja"

On my wagon I was able to change the supply hose without draining the tank. I clamped the hose and removed it from the metal fuel line. Installed the new line on the metal fuel line, unclamped the tank end of the original line, pulled it off and then put my finger over the outlet. I was then able to quickly put the new hose on without losing too much fuel.
My 77 is leaking now and it's got the original crimped fitting on the outlet line so I'm going to have to drain the tank to do that one. I plan to do it by using the fuel return line. I'll put a long fuel hose on it in the engine compartment and then have the engine pump the fuel into a container until the tank is empty.
Can't help on the viton.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Same thing just happened to me. I also think the B20 caused the braided line to deteriorate pretty rapidly. But apparently this wasn't the first time it was replaced since the OEM part is crimped below the tank and you have to screw the end in to the bottom of the tank. It also doesn't have the braided exterior, just smooth black rubber. It seems much more durable than the braided line but still not Bio-resistant surely. The part was about $12.53 at ***************.

I replaced it today and my tank only had about two gallons in it. So I jacked up the car and removed the end on the steel supply line and let it drain into a 5 gallon gas tank that would just fit under the car whilst jacked up. When it was empty, I replaced the part and put the diesel back into the tank. Mine was only leaving a small mark on the pavement so I figured I would run the tank down before I attempted to do the repair. I drive about 300 miles a week so it was not long.

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1993 W124 300D
-297K on the clock as I type this.

If your fuel gauge does not read extremely accurately, i.e. similarly to 90% of these cars, verify how much diesel you have in the tank by pulling the sending unit and visually checking the fuel level. Or just pull it when your gauge reads almost empty and take it apart and clean the contacts, should only take 15-20 min tops. Knowing exactly how far you can drive to get the tank as empty as possible makes all the difference in the world as far as doing this job. I mean the job of replacing the fuel line/lines under the tank. Also if you're lucky the tank strainer will come out when you unscrew the brass fitting for the fuel line and you can replace/ clean it as well.

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1985 300D Gretchen (Astral Silver) 220k
1983 240D 4-speed Evelyn (Orient Red) 203k


TANSTAAFL

I have heard that you can hook a shop vac to the tank, and draw a vacuum, but on a full tank, you may actually suck fuel out that way... but you may want to rig a intermediate tank to your vac hose, and see if any fuel gets sucked out. with the tank under a vacuum, very little would drain during swap of hoses.
I doubt the tank screen gasket is leaking.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!