Well the good news is the adding coolant fixed the issue but the bad news is I found out WHY the engine was low on coolant.....the servo is leaking at the bottom. The servo/climate control systems works exactly as it should and considering I don't drive this car in the winter I'm weighing my options. Once I park it for the winter I'll probably do the bypass (with a vacuum valve I have from a later model at the pnp) leaving the servo in place. I guess the only issue with that would be the temp switch causing the blower to come on when heat is called for. I'll start another thread when I get around to this.

The car has the ALUMINUM servo as well which they claim is better and does not crack like the plastic.

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

Sorry to hear about the 'bad' part, but I'm feeling kinda' good about Post #2.

[gloating mode OFF]

Yes, you were correct. I acknowledged your statement as a possibility but I wasn't quite sure how to verify the level since I've never dealt with one without an expansion tank before.

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

The servo blocks coolant flow too, that's how it controls heater output.

-j

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I have a good working plastic servo if you want it.

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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 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Hey V-tech,
How much you want for the servo?

I REALLY don't want to bypass for heat, but this winter is going to be a doosey.
I would rather just replace the servo.

Let me know,
Ginny

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Ginny in Denver-ish
78 300SD, 265K (mine)