Mr. Carlton,

4hrs total time with block heater plugged in 5PM to 9PM
Ambient 65F @ 75 percent humidity
110F measured with thermometer (small Chef's type) wedged between
crossover and valve cover.
43C As measured by 124.128's dash Temperature gauge.

(Bonus information for me:W124's dash gauge is accurate (at least at 110/43)

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'84 300SD sold
124.128

As expected........just enough to allow the engine to start like it's summertime. It won't get that warm if the ambient is 0°F. however.

Plug it in when it's quiet around. You should hear a faint "singing" just like an electric kettle......

Yup, I agree - easiest way to know if your block heater is working is to plug it in and listern. Do it some place quiet so you can hear the faint sizzle and humming noise as it heats up. Easy to hear if you are under your car - like when you change your oil or something.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman

The power cords like to fall apart and get brittle where they connect to the heater, I'd replace the cord. Both of them on the old engine and donor engine of my dad's SD were showing the wires through at the heater area.....if we had plugged it in it would have promptly shorted out. We threw out both cords. He doesn't really need a block heater since the car is sleeping all winter.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Spark3542,
All I'm looking for from the Block portion of the Heater Plug is the ability to
Conduct Electrons.

__________________
'84 300SD sold
124.128