I bought a 1984 190D with the 2.2 diesel from my grandmother last summer and, just in the last three months, the electro-mechanical fan has quit working, the heater has stuck on and the enigine diesels every time I try to shut it off. The manual shutoff works every time, but I was wondering if any of these problems are related. Regardless, it would be nice if anyone could shed some light on any one of these problems. Thanks in advance.

-Blake

My Error: Your mono valve is bad. RE: Heat on all the time.
Thanks jbaj007 my mistake, could not consult FastLane to verify part.

Suspect leaking vacuum lines.
You need to test the heater valve vacuum motor.
Very possible you have cracked or brocken vacuum lines causing both problems.

Our hero:
http://www.mityvac.com/

Replace fan clutch electro mag... $118 Fastlane

New heater valve...$20 (Don't think the 190D has a monovalve )

It "continues to run" (of course it "diesels"; it's an OM ), usually a leak in vacuum system somewhere. Time for the superhero of diesels....The Mityvac!

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

You are correct, vacuum valve.
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1BI00S9Z5&year=1984&make=MB&model=190-D-001&category=R&part=Heater+Valve
1984 Mercedes Benz 190D 2.2
Part: Heater Valve
Vacuum controlled.
R3020-11893 Heater Valve IN STOCK $19.80

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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/

Thanks for the help.

-Blake