While checking my see-through fuel filter on the 240D I saw black granules inside. Took it off and shook some out. They were hard, not soft like I expected algae to be. Is it algae or could it be deteriorating fuel lines? I am the fourth owner of a low mileage car. It could have been sitting around in its earlier life. I have used PS Diesel Kleen but I haven't changed many hoses other than the injector loops.

After reading ten pages of posts on a search I don't think I'll have trouble sleeping tonight.

__________________
Rick
Avid Benz watcher

Previously owned 126's: 2 1981 300SD's, 1987 300SDL, 1991 350SDL,
Previously owned 123's: 1978 300D, 1983 240D, 1985 300D
Previously owned 124: 1994 320TE

Currently:
2004 Toyota Sequoia SR5 206k
2010 Ford Edge 122k
Always looking for the next MB diesel!

#1. Algae.
#2. Contaminated fuel.
#3. Rubber.
#4. Corrosion.

Have a great day.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

I'LL go with one of Mr. Hunter"s alternate solutions :
decomposing HARD rubber fuel lines !

About how many feet of the small rubber fuel lines are there on a 123? What size is it?

__________________
Rick
Avid Benz watcher

Previously owned 126's: 2 1981 300SD's, 1987 300SDL, 1991 350SDL,
Previously owned 123's: 1978 300D, 1983 240D, 1985 300D
Previously owned 124: 1994 320TE

Currently:
2004 Toyota Sequoia SR5 206k
2010 Ford Edge 122k
Always looking for the next MB diesel!

About how many feet of the small (5/8"?) rubber fuel lines are there on a 123?

__________________
Rick
Avid Benz watcher

Previously owned 126's: 2 1981 300SD's, 1987 300SDL, 1991 350SDL,
Previously owned 123's: 1978 300D, 1983 240D, 1985 300D
Previously owned 124: 1994 320TE

Currently:
2004 Toyota Sequoia SR5 206k
2010 Ford Edge 122k
Always looking for the next MB diesel!

I believe its 7.5mm fuel hose. There is a fitted hose at the tank (not just bulk hose) which is about a foot long, then I'd presume they have another foot or so of hose for return at the tank. Everything else is under the hood.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Thanks! I guess I'll be cleaning some nasty with those diesel soaked rags huh.

__________________
Rick
Avid Benz watcher

Previously owned 126's: 2 1981 300SD's, 1987 300SDL, 1991 350SDL,
Previously owned 123's: 1978 300D, 1983 240D, 1985 300D
Previously owned 124: 1994 320TE

Currently:
2004 Toyota Sequoia SR5 206k
2010 Ford Edge 122k
Always looking for the next MB diesel!

I have a dumb question about the return fuel hose on the 240D.

Why is the hose buldged out like that? I replaced it with a standard fuel line, because it was leaking and I didn't have local access to "cigar hose".

__________________
'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.

7.5mm inner diameter for the fuel hose. Get about 2 feet. Under the driver side at the fuel tank you will find a vent and return line. these use about 6 inches each.
On the pasenger side of the rear you will find the screen and fuel line that goes into the screen The screen uses a 46 MM wrench to get it out. Buy the fuel line that goes into the screen. Take out all the fuel by disconnecting the screen hose and allowing the tank to drain. Clean the screen. If it is broken, replace it. Use brake cleaning fluid to clean it.
In the engine compartment replace the rubbe hose that is attached to the inline filter. Replace your inline and main filter.
Get a new "cigar hose". The injector pump does need it to absorb pulsing from the injection pump.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

dmorrison,
Please forgive me but what did you mean by this statement?

__________________
Rick
Avid Benz watcher

Previously owned 126's: 2 1981 300SD's, 1987 300SDL, 1991 350SDL,
Previously owned 123's: 1978 300D, 1983 240D, 1985 300D
Previously owned 124: 1994 320TE

Currently:
2004 Toyota Sequoia SR5 206k
2010 Ford Edge 122k
Always looking for the next MB diesel!

MB in India factory installs pre-micro dual fulter combo along with a sedimenter. The sedimenter takes away the sludge and water by a centrifugal process and can be commonly found in commercial diesel vehicles, it really prolongs the life of the pump and injectors.

Why would that be? The line is the return line to the fuel tank. their is no resistance to the fuel in that line.

__________________
'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.

Sure there are surges, everytime a cylinder fires the IP would surge the fuel. The fuel would be pushed all the way back to the tank by these surges. It has been noticed by a few people that if you put a normal hose in place of the cigar hose that the IP will have a little clicking noise while running.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

No difference in the sound of my IP and I can't feel any pulsing of the hose, but I will defer to your experience and order the hose. What's $12 if it could prevent some serious problem later.

__________________
'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.

I noticed just a little bit of difference in sound myself, I once thought to myself that hose it is ready to rupture! So I went ahead and replaced it (on both my W123s, at the time) to find out a week later it was like that on purpose, doh. Seems like it only cost about half that to replace though.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k