1981 300SD question:
I need to replace one or both fuel hoses, under the tank, above the differential, fuel is leaking bad. I have not done this before but it looks like I would need to drain the tank to do that. Am I right, and if so, what's the easiest way to drain the tank? The hoses are $20 from the dealer and I am going to get them from there since these have taken more than 20 years to fail.

This ought to be a snap!

Get yourself about 10 feet of clear tubing which is large enough to fit over the end of the fuel lines coming out of the bottom of the tank. Put one end into the end of a 5 gal. container and the other over the end of the fuel line. (Hemostats on the fuel line before you remove the clamp and nary a drop is spilled!) The tank sits high enough in the car for gravity to take over from there, especially if you have the rear of the car on ramps.

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Sam

84 300SD 350K+ miles ( Blue Belle )

The number of cans you will need is based on how much fuel you have in the tank. The less the better. Important: Check and clean the tank screen while the thank is empty!!!

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N. Hodges
1994 S350
1987 300 SDL (for sale)

$20 for couple of sections of crappy fabric covered rubber hose...... Why dont you buy superior American fuel-line hose with internal wall fibers for about $1.39 per foot??

And while you are at it, might as well get 10-12 ft of hosing to replace ALL hose sections of fuel and return lines (except the cigar section) as long as the tank is disconnected. Just use a razor blade to make the cuts - and also replace inferior skinny & rusty MB hose clamps with superior stainless steel wider American ring clamps too.

Those old fabric covered hoses can cause insidious leaks after 20 yrs without you even knowing it. They should probably be on everybody's list of items to be replaced each 20 yrs or even sooner.

I saw this problem on my 280SEL last Summer when it seemed the engine was getting 10-12mpg. Sure enough the fabric hoses looked dry but became wet just by prodding or bending them.

You guys are good. Will try it later today and save myself some money as well.

Yall must be youngsters wanting to do this the hard way....
Take that same clear tubing and cut 8 inches off it...
then put the long piece into the tank through the normal fuel filler opening.
Place the other end in a 5 gallon fuel approved can.
Take the short piece and place it next to the long one at the top of the filler tube... place the rag around both of them to seal the air off... then blow into the short one. This will start the fuel running into the can... take the rag off so air pressure can get to the tank... thus you are syphoning the fuel out....

Actually, not as young as you think. I only wish I was sometimes.

Since the rear of the car is on ramps anyway, I found it saved a step by just letting it drain from the bottom. You have to be under there to change the lines out.

Also, on the 126, those lines have a crimped fitting on the end that screws into the fuel screen and a "worm" clamp on the end attaching to the hard line which runs forward. You will need to order them, about $20 for the feed and $7 for the return.

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Sam

84 300SD 350K+ miles ( Blue Belle )

What's a tank screen and what other hoses would I need to check.

The tank screen is a cylinder type, strainer that screws into the bottom of the fuel tank. It keeps the large chunks from entering the fuel lines. The feed hose screws into a flange which is the bottom of this fuel strainer. It takes a 42mm wrench or socket to remove it (huge but low torque).

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Sam

84 300SD 350K+ miles ( Blue Belle )

Greg...

I just stuff the hose in, close off the filler neck with a rag, then blow in the hose until I can't blow any more air into the tank. Then I quickly stick the hose in an appropriate container. The hose has a long enough run that I don't even spill.

But I might try your extra hose trick. Might work real well with an air chuck.

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Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Ya'll must have clogged tank vents if you can blow pressure into the tank that way.

Phantoms, What do you mean ? We are talking about putting air in where you usually put fuel....

And this air should escape out the tank vent, correct. At least it did on a 240D I cleaned the vent line out on.

Do you mean the overflow line which goes from the fill area inside by the tank and exits to the ground ? Isn't the tank vent inside the cap... so with it off it does not count....

Maybe it's different on the SD, but on the 240D that line is the tank vent. The cap is not vented and if that line is blocked, the system will pull a vaccum. I'm pretty sure it's the same on my CD, but I haven't checked to confirm it.