My 300 SD had been starting with no problems and yet yesterday when I went to leave work, it would not engage the starter at all. It was in the lower 30's. Battery appears OK, terminals cleaned. Previously, replaced a faulty glowplug after tests. The GP Relay does "clunk" after a few seconds. I tried the trick given in many of the threads of jumpering 1 and 3 on the terminal on passenger side but got only weak spark no solonoid click. Later took the wires off the terminals and cleaned them as the terminals were highly corroded. After that the jumper trick between 1 and 3 resulted in a notable solinoid clunk but starter didn't turn over.

That seems to indicate the starter, but I have had no warning signs of starter dragging or solenoid not working. Is it maybe only the solenoid ??

I will also pull the battery and have it tested but it gave no warning signs either.

Ideas would be appreciated?

Thanks

Sounds like a low battery to me. Could be the battery itself has reached the end of its useful life, or perhaps there is a malfunction in your charging system. Put a voltmeter on the battery, with and without the engine running to test the viability of your charging system.

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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

OK Kerry I went to check the battery voltage and decided to jumper the terminals to see how far the voltage dropped. The battery was 13.2 at rest and dropped to 11.75 trying the jumper

But starngely the starter truned over and I tried the key and it started.

I has been in the garage several hours and I am wondering if having warmed up has caused this and if so what are the possible "villians" to look for. In KC it get COLD, so I have to find this.

Thanks for you time and ideas

Voltage seems ok. I'd be thinking a bad connection somewhere on the starter or a bad starter.

__________________
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

I will check the connections to the starter. The jumper terminal was really corroded. Maybe a simlar fate has fallen on a connection to the starter.

After that I will put it outside the garage and let it sit overnight to see if the problem is really fixed.

Any way to truly test the starter for these kinds of suspected problems?

Have you looked at the condition of your shift rod bushings? Worn or missing bushings may not be allowing full engagement of the neutral safety switch on the tranny.

http://web.infoave.net/~ontheriver/automobiles/w126shifter.htm

-Scott

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https://goo.gl/photos/J8ZUVvAYiYqLxbD18

1989 560SL 111Kmi
2007 E550 4Matic 157 Kmi
2000 F250SD 7.3l, 1996 Explorer Ltd 5.0l
1965 VW Beetle Deluxe 115 Kmi
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Previous MB:
1983 240D Euro Manual 144 Kmi
1983 300SD 495 Kmi
1986 190D 2.5 100 Kmi
1986 300SDL 202 Kmi
1991 300D 2.5 Turbo 91 Kmi
1998 E320S4 (4-matic wagon) 140 Kmi

How old is the battery?

If it's four year old.........or more...........take it out and have it load tested. The capability of a battery in the cold can only be determined by a load test.

Or, if you want the reliability that you mention, if the battery is four years old or more.........just replace it.