The 240D is dripping coolant from the driver's side (foot) arm on the manual heater control. As a result of searching, I found I have two options: 1) New Unit or 2) Replacing the O-rings in the one I have. Has anyone ever taken one of these apart? Any tips on removing the cables and/or hints regarding disassembly would be appreciated.

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

Alright, I guess I'm going to be the guinea...

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

bjcsc,

I am not sure exactly what the problem may be. I am a little confused about where the leakage is coming from. The control knobs on the 240D operate a valve on the bulkhead in the engine compartment, on the passenger side. These can leak and are easy to replace, but I am not sure they would leak into the car, necessarily. If the leak is inside the dash it is probably the heater core. I do not think these are fun to replace. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Jim:
It's not leaking into the car. It drips from the arm on the heater control in the engine compartment,
the one that the foot control opens and closes, which is the driver's side of the control unit.
I have removed it and disassembled it. The little O-ring on the right in the picture is the one that was leaking.
I didn't use a flash for the photos, so they are mediocre. So far no luck in finding a replacement O-ring.
Any ideas where I might find one? Went to all three auto stores today - BoatUS tomorrow I guess...
Or do you think I am wasting my time and should just get a new unit?

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

bjcsc,

That is the heater control valve and it is about $45 or so from Fastlane for your car. I have had to replace that once for a similar problem. Finding the parts will be a chore and I would replace the unit just to be sure it was not going to leak again.

That valve should be manipulated by the heater dials not the air flow direction sliders. There is one for each side of the car (one knob and a corresponding valve for each heater control knob/dial - rotary action device with a red arrow icon) Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Hey Jim:
I apologize for confusing you. By "foot side" I meant the right side of the control panel in the car (my understanding is that the passenger side slide diverts between windshield and floor while the driver's side slide diverts between windshield and dash vents). I know the rotary knobs open and close the valves on the control unit, but the passenger side rotary actually controls the driver's side on the valve control unit in the engine bay. That's where my leak was. Believe it or not, I actually found the O-rings today. They are readily available at Lowe's of all places, in the plumbing section. It's a #78 O-ring, Lowe's part #96715. Total $.36 for two. I sealed the end caps back on with PVC cement and will reinstall in a couple of hours to see if I am successful. If not, I'll be calling Phil tomorrow. Thanks for the responses.

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

It's fixed!! Reinstalled the unit, warmed the car up to operating temperature, full heat and no leaks. About the only thing that was tricky was removing the cables from the arms on the control. They are wrapped around the arm. If you grab them with pliers and rotate against the direction they are wrapped, they open up like a spring and slide right off. Other than that, this job was a piece of cake once I found the O-rings.

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

bjcsc,

Wow, sometimes the tenacity of you guys amazes me. Congratulations on that fix. To think I spent the money to buy a new one when, for less than a dollar I could have fixed it. Well, I still have the old one (never throw away something that looks like it comes apart without taking it apart) so I may be buying a few seal rings from Loews. Congratulations again and thanks for sharing what you did. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)