a popular topic, this.

the current theory is to not glow, just crank till it starts which works great if we're warmed up and seems to take about 6 seconds in the 38 degree mornings here in oregon. but my new 900CCA group 49 doesn't always want to turn four that long.
all things being equal, how long do we expect to be able to crank a cold 300D. my battery guys says the problem is not enough reserve amps--that's why i cant both glow & start. i'm wondering if the starter/solenoid is going south.

1984 300 turbo diesel, 110K miles, 20/50 multi-grade oil, regular service to this point.

tia, john

hans,

My opinion on this, based on well over half million miles driving MB diesels, is that you need the glow plug system in good shape. If it is not, you are sending the starter, the expensive starter I should say, to an early grave.

BTW When the starter time comes, don't waste your money on a non Bosch authorized rebuilt starter.

Best of luck,

John, my '79 300D won't even fire on a cool summer morning if I don't use the glow plugs for 3 or 4 sec. In winter, (-5F) I glow for 12 sec. After cranking for 3 sec, it starts right up. The good part is that the plugs stay on while cranking. On cold days you only get one chance at it. Glow plugs are much easier and cheaper to deal with than a worn-out starter.

I am not sure about the batter size, but it sure is heavy!

Glow! With the plugs! That's why they're in there! As an example, my wife uses this simple method in her '96.

Open the door, get in, sit down, close the door.
Insert the key, turn to position II but not to START.
Ignore bells, buzzers, dash warning lamps, etc.
Put on seatbelt.
Adjust the seat (or press the appropriate seat memory button; memory power seats are HEAVENLY! )

By now the buzzers are quiet and the glow indicator has gone out.
Turn the key and start 'er up!

In the '85 I had to remember the Owner's Manual instruction to HOLD the key in START until the engine was running, or it sometimes would not keep running.

BCingU, Jim

Hanss,
As a diesel owner for going 4 years,(Ford 6.9 and 300D), I'd urge caution cranking without using the glow plugs.I use mine whenever I have a cold start situation. Posts on the Ford Diesel website mention the possibility of the plugs coking up if this practice is used on the Navistar V8 diesels, making them possibly difficult to remove. Once a plug sticks in the head, if the end should twist off on removal, the head will have to come off!
I can't say that the Benz would do exactly the same, but why risk excess battery/starter wear? The Fords have dual batteries, but our Benzes only have one.

Regards,
Nate Stanley
'79 300D
'85 F-250 6.9L

I use the same technique as 123 300D driver. If your battery can't heat up the glowplugs for 10 sec either there's a short in the glowplug system or your battery is marginal. The glowplug system is only a few components and should be pretty straightforward to get in shape.

My car has started as cold as 8 deg F without a block heater, and I triple glowed the thing and botched at least one cranking attempt by stopping cranking before she fired. It did take about 20 sec (seemingly) of cold cranking for the engine to keep running. I think my Optima battery (red-top) helped turn the sucker over. The winter before, I did kill a perfectly good Interstate battery trying to start a not-plugged in 77 300D in 20 degree weather. And I know that battery was good, because after charging it, I took it to National Auto, and it delivered 200(!) amperes and the voltage stayed at 11 volts.

Also, I see you're using 20W50. That may be too thick. Is this your first winter? Not sure where you're at, but I use 15W40 Shell Rotella T or Chevron Delo 400 here in eastern Pennsylvania. Even that is like molasses in cold weather, but I can't find a thinner CG-4 rated oil for sale around here, and nobody seems eager to mail-order oil (if it's even legal).

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

a trip over to my battery guy this morning yields a solution to the problem. first new battery is real strong , 900CCA no problem, load tests at 1200CCA and recovers fine. my man, troy, slips his neat induction ammmeter over the battery cable, looks closely at me and asks. "what all accessories you running?" just the clock, i reply. "gotta trunk light?" "oh ya, replaced the bulb last month." we go look and troy burns his finger on the hot bulb and we both realize why there is that .8 amp on the meter.
so for the past month i've been merrily discharging the battery, all day & all night, due to a failed switch. amazing that the bulb just kept putting out. and the cold weather was more or less a coincidence.
so thanks for the replies and i'll go back to glowing and thinking about all the money i could of spent here.

hanss

Very cool. I had the exact same thing happen to me, except I ended up buying a new Optima battery that I really didn't need. (Anyone in Eastern PA looking for a battery? )That trunk light killed my battery within 3-5 days. I somehow figured this out when I burned my hand pulling out the bulb which should have only been on for about 5 seconds. That was the only time my car left me stranded, and if I had had good jumper cables instead of the broken cheapies I had, I would have been fine.

Anyway, glad to hear you're back on the road. I keep a DC Voltmeter plugged into my cig lighter so I can keep an eye on my battery voltage. Today I saw 14 volts DC with no accessories, but usually I'm more like 13.4 volts or so. If I use my rear defogger and a couple accessories I drop to about 11 volts. After I shut off the car, I drop to about 12.6 volts, and while glowing i might be at 10.5 volts.

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

Robert, your last paragraph is exactly what I have been doing...watching the voltage while I drive with all of the accessories on. I guess my beast must be running properly, because I get exactly the same voltage numbers that you describe. What are the chances of that happening?

About the oil, I have been using semi-synth 5W30 and that's why the engine will start down to -5F without using the block heater. I got this stuff from a local farm supply shop. In summer I use 15W40. Switching to the 5W30 made a substantial improvement in cold cranking speed. I wouldn't trust my car starting at -5F with the 15W40 stuff, no way! I think it would be reliable down to only 5F. Also, the oil pressure drops about 2psi with the thinner oil though.


Gary