Date registered: Nov 2008
Vehicle: 1981 300TD 310k--1966 230 165k--1970 280se 172k
Location: Ohio City, Ohio
Mentioned: 1 Post(s)
Quoted: 33 Post(s)
Once the car warms up and starts to stumble, you may try adjusting the air mixture valve. It's on the right front of the engine and looks like a large slotted screw with a knurled edge. It will be on a hose coming over from the air filter assembly. Take note of its position should you need to return it to the original setting. Clockwise is less air and vice versa.
It may be that your engine is starved for air once the thermostatically controlled air-mixing starting valve closes all the way (the name of it escapes me right now). So you should start by turning the valve counter-clockwise.
The factory procedure for adjusting this valve requires a CO2 exhaust reading or (less accurately) using a vacuum reading off the throttle housing. You can just wing it to get the car running better and later get an accurate adjustment.
1981 300TD--310k miles
1970 280sel--172k miles
1966 230--162k miles