Could be a bad connection on the battery cables or a sticky solenoid as a result of cold grease. Also could be a bad connection in the ignition switch. My TD has a tendency to do that in very cold weather and the problem lies in the ignition switch. When it occurs I just jump terminals 1 and 3 in the junction box on top of the fender in front of the battery and off I go.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Check all the major battery connections and grounds- clean them. Also check the ground to the block. You can measure the resistance from the engine block to the battery ground- should be low 1-2 Ohms.

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81 300D Turbo 190K sold
83 300sd 319K best $500 I ever spent-daily driverw/ 2 tank WVO set up

Cool, thanks for the advice. the 15 second crank seemed OK, but I don't know what is normal for these cars starting near 0 deg F with no block heater.

kerry, thank you for the jumping advice.

ill also look at and clean my electrical connections.

Maybe related or not, when I press on the accelerator the lights get slightly brighter, and then dim down to normal when I let off the pedal. i would think voltage regulator...i havent looked at it yet.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

All of the above can cause the problem as well as what vstech said.
Here is a pic of the terminal block to jump in front of the Batter (on an 84 300D). Also another area that sometimes needs the contacts cleaned (cleaned with the battery disconnected of course).



This is a pic of a Delco starter however it is similar to the ones on my year of mercedes. You can see the 2 contact bolts and the Disc (not labled) inside of the Solenoid that vstech was speaking of. However, I am not sure those bolts can be rotated without removing the plastic(?) End Cap
on the Solenoid as I believe the bolts have a square section like a Carriage Bolt the fits into a square holes in the End Cap.
If you try to rotate them from the outside I believe it will crack the End Cap.
However, I have not been inside a Bosch/Mercedes Solenoid to say for sure.

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84 300D, 82 Volvo 244Gl Diesel

cool. ill have some time today to look into it.

any ideas from a couple posts ago on why my lights brighten when the engine rpms increase?

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Because the voltage climbs when the alternator has a decent output above idle. They usually cannot maintain 13.5V at idle with the headlights on.

Thanks Brian. Good to know this is not an abnormal happening on these cars. I've never noticed it on my other 300D.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car