I have not been able to get an answer thus far on identifying these two parts.
The first one is a plug with various resistors inside. Pulling the plug out and changing it's reference number changes the resistor to another value. I am guessing, knowing very little about my new Benz, that it may have something to do with the glow plug time delay, but that's just a stab in the dark. It is located just forwardd of the brake MC & booster.
The second part is a high wattage ceramic resistor. It's burned out and I need to know what to ask for, but, what circuit is it in? It is located just behind the left headlamp.
As always, your help is appreciated.

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The dial is a trimming plug for idle control. Turning the knob should raise or lower idle in 25 or 50 rpm increments.

The big resistor is probably for the low speed setting of the auxiliary fan.

Sixto
93 300SD

I was wondering the other day what that dial was. Good to know. I can't believe how easy MB made it to adjust the idle on this engine.

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

Thank You !!! It make sense that the resistor is for a reduced speed to the fan, as that would be a bit of current.

The Idle control doesn't actually turn. It's a plug, which must be pulled and reseated in one of the other positions. I never would have guessed it's purpose, and I don't think I ever played with it while the engine was running.

The trimming plug is indeed idle speed control. You may be able to find the actual idle speed associated with each value by using the search feature. The workshop manual also contains this information.

The big resistor is for low speed on the big electric fan. Low speed is triggered by the high side pressure within the a/c system. It's the red or green switch on the a/c dryer. High speed for the aux fan is triggered by engine temperature - 105C, if memory serves.

- JimY

Thanks JimY,
With these temps we've been seeing (predicting nearly 70 this weekend, when we should be shoveling snow) It's nice to know that the high temp will still function. I am suspicious that my viscous fan clutch is toast, it has little resistance even after sitting, so I doubt it will go into lockup.

Sounds like your fan clutch is in need of replacement. I am planning on upgrading to the late model plastic 11 blade fan with its cheaper fan clutch, there's info on this conversion on the Forum. The weight of the fan is less than the original metal one and that I believe helps extend the life of the thermo clutch. I've replaced a few of them and can say they sometimes have disappointing life. A few guys claim to have injected new viscous fluid (Toyota sells it in two viscosities) into the clutch but I never tried that. YMMV

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!