I have been under the impression that the gloplugs cut out in non-afterglow models as soon as the starter is engaged (sudden voltage drop).

but perhaps they don't cut out until the starter is disengaged? But I doubt it because usually you want max power for starting. No doubt the afterglow models are a different story.

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1983 300SD with bad undercarriage rust, with old greasecar 2-tank conversion. About 200K miles, just an adolescent but with premature bone disease.

Correct. The 12V signal to the starter also goes to the glow plug relay. When that 12V disappears (when the driver releases the key), the glow plugs shut down.

Funny, this is what first came to mind for me. My friend's Jeep wouldn't start one morning (well below zero in WI), and I used a heat gun to blow air directly into the TB. Started right up.

I have also seen the charcoal trick used on heavy equipment.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I have been using a blow drier under the hood and coleman dual fuel camp stove under the oil pan(perfect height) to help start my 240d on these cold mornings. (New glow plugs and reamer on the way!!!). I tried the lower radiator hose heaters, but after buying two bad units I am done with them...ordered a OEM style block heater, but for the mean time the blow drier and camp stove will have to do.

Be sure to use some kind of additive to prevent gelling when you fill you tanks...do not rely on the stations winter blends not to gel!!! You are better off filling up at your local truck stop to be sure you are getting the best fuel. As mentioned above, Power Service works great if your fuel does gel.

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1981 240D

Had some issues end of last week when it was 0 deg.or lower. I did not have any kero in the tank my new lower rad hose heater is kaput and i have not changed the oil yet.

Yes I am cheap I have about 800 miles before I am due for an oil change. I did pick up the oil and will change it Tuesday.
The old girl would not fire ,turned over like it had mud in the crank case. It is going to be in the low teens for the next few days so we will see what happens.
The lower rad hose only lasted a month pretty bummed about that. I think I will get the right block heater.

I replaced the first three GP's and it starts worse. It used to run smoothe in seconds now it shakes and smokes for 15-20 seconds. Why is that? I noticed that the new Bosch have a taperd tip and the old GP's were just rounded. The old GP's looked good and heated up nice,I may put them back in.
Where can I get a GP reamer?

Forcing the engine start when you have mud-like oil in the engine is REALLY hard on it; how long does it take to extinguish the oil light? You are NOT saving money by postponing the oil change.

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I choose to be happy, even when the Mercedes is being awkward, lol

Last week while reading back comments on cold start issues, I found a comment that recommended using the dome light as a indicator of when the glow plug cycle was complete. Living in Buffalo, New York allows me to field test comments like this, and it WORKS! Rather than depend on the curly que lamp on the dashboard, wait for the dome light to brighten (following the glow plug cycle), and your car will start much faster. I recommend 2 dome light cycles for 15 - 20 degrees, and 3 or more anything colder. I wish I could recall who or find the original thread, but have not been able to. Regardless, while it is not my idea, it is my new winter starting policy!

The oil pressure comes right up, I have since changed the oil and it has helped with the cranking. It is still running rough at start up. I am going to put the old GP's in tommorow and look at putting in the new block heater too.