There seems to be a lot of misunderstanding here about these cars are designed to be started in these cold temps. The manual states to start cranking the car as soon as the glow plug light goes off and to not release the key until the engine is firing normal. It goes on to say cranking up to 60 seconds is permitted. The comments about this burning up the starter are ridiculous. This is not going to hurt the starter, it was designed for this. Next myth is glowing it 2-3 times before cranking it. By doing that, all you are doing is running the batter down further before even starting to crank it. Glowing it 2-3 times will not make the plugs get any hotter.

This motivated me to refer to the Owner's Manual for my 1985 (yes, times have changed but here's the official company position at the time) 300CD.
From page 89:
"At temperatures below 0^ C or 32^ F use winterized or No. 1 diesel fuel only. If not available, a certain quantity of kerosene may be added. Mixing only to be done within the car's fuel tank. Kerosene has to be filled in before the diesel fuel.

Engine power may drop according to the proportion of kerosene. For this reason, keep percentage of kerosene added to the minimum necessitated be the ambient temperature.

The following table can be used as a reference, if adding of kerosene becomes necessary. The mixing ratios shown refer to the total mixture.

Ambient temperature No. 2 Diesel Fuel Kerosene %
0^ C to -10^ C / +32^ F to +14^ F 70 30
below -10^ C / +14^ F 50 50

Even in extreme climatic conditions, the maximum mixture ratio should not exceed 50%.

Adding of kerosene to No. 1-D diesel fuel is not recommended even at low temperatures."

No mention of adding gasoline. The idea that M-B would officially suggest adding gasoline to my diesel fuel tank seemed unlikely (but possible) to me.

Standard disclaimer: Your mileage may vary.

When the car is really cold, my 116 starter will jam when I try to start it and stop the cranking. I assume the starter is getting caught on the ring gear or maybe the starter isn't healthy?

__________________
'80 300SD - '83 240D - '00 E55 AMG - '02 G500

The misunderstanding is in not having the original cold starting drill tag, it clearly says to cycle the glow plugs at least twice and also to hold the accelerator pedal to the floor during cranking and once it starts until all the cylinders are firing .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Keep in mind that, after 34 years, when the light goes out may or may not be accurate. On my 91, the light is still very accurate....but I've had other diesels where the light clearly went off way too soon.

When it's really cold, best to glow until the relay clicks off, not until the light goes off.

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

The relay is supposed to vary the lamp's timing by temperature, the one in my '84 300CD still does, this morning in balmy 43* F temps the seat belt lamp went out before the glow lamp went out by a fraction, the instant the GP lamp went out I cranked it and it instantly started .

Glad I'm not suffering the Arctic Blast so many are .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

It's *supposed* to, but as with so many other things, they do wear out and tolerances of the capacitors will drift with time. I know the one in my car would only run the light for ~1 second, then time out the relay after 8 seconds. Recapping it brought back the correct time-vs-temp glow time and has the relay timing out after 35 seconds.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

If I had an alternative gas car to drive on days like that. I would use it as there are so many things that may deny you the start. First being the fuel. The other issue is few cases of cars this age will still have everything kept up to pretty much as new condition.

It was nice to see the compression numbers still as high as quoted though. At that accumulated milage.

The constant somewhat colder weather than what seems normal to me has broken now. It was not really cold like the Midwest out here on the east coast of Canada. Just pretty much constantly lower than normal temperatures. Based fairly on us using far more fuel overall so far this winter than average for home heating.

Where might one find these caps in the car?

__________________
RenaissanceMan Labs: where the future is being made today.

Garage:

2017 Chevy Colorado Diesel (nanny state emissions)
2005 Volvo S40 T5 AWD, 77k
1987 Mercedes-Benz 300D turbodiesel, 4 sp auto, 156k - 28.7 mpg
1996 Tracker 4x4, 2 door, 16v, 3 sp auto. 113k - 28.6 mpg

WARNING: this post may contain dangerous free thinking.

"Recapping"? I don't know what this means. Could you please elaborate?

Replacing the capacitors on the GP control board.

__________________
RenaissanceMan Labs: where the future is being made today.

Garage:

2017 Chevy Colorado Diesel (nanny state emissions)
2005 Volvo S40 T5 AWD, 77k
1987 Mercedes-Benz 300D turbodiesel, 4 sp auto, 156k - 28.7 mpg
1996 Tracker 4x4, 2 door, 16v, 3 sp auto. 113k - 28.6 mpg

WARNING: this post may contain dangerous free thinking.

Ah! After reading Diseasel300's post of earlier today, I thought: How about replacing the capacitors? I wasn't familiar with the "Recapping" terminology. Thanks for the clarification.

So yes, I wonder:
> Might replacement of the capacitors be a worthy endeavor after 30+ years of service? As you asked: Where are they? What are their specs.? Etc.
or...
> Replace the glow plug relay control board with a rebuilt board (assuming someone is rebuilding these items)?

Glow Plug Relay Troubleshooting...

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Thanks for the link to that nice write-up. Even though I have a 617.x, I appreciated learning more about this subject for the 603.x.

I've actually never looked deeper than the glow plug relay strip fuse to see if my rig has the sort of board as the 603. I'll be checking on that.

Thanks again-

The early 603 glow plug relay is very similar to the pencil glow plug relay for the 617's. It may have capacitors in different locations or different values, but the construction and function is very similar internally.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)