Battery voltage at idle with a fully charged battery and no load should be 13.8 - 14.2 VDC. Additional loads will lower the voltage accordingly.

I suggest fully charging the battery, starting the engine, let it run for 10-15 minutes and check the voltage across the battery at idle without a load. If the voltage is not 13.8-14.2 VDC there is a problem with the charging system e.g., alternator, regulator and/or wiring.

An easy way to detect a slipping belt is that the pulley gets VERY hot from the sliding friction. Hot enough to burn your skin.

If the voltage is 13.8 - 14.2 V then the problem is likely the starter and/or solenoid.

Good luck!!! Keep us posted...

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Unless it charges @ 13VDC + , it's never going to have a fully charged battery .

Do the basics before you go throwing $ at it ~ I had low charge from all brands other than BOSH, several were German made, a surprise to me .

The jumper charge pack can have 1,000 amperes but if it has 4Ga. cables it isn;t going to work .

The Mercedes OM661 engine requires 800 CCA to crank quickly ~ yes i have jumpered with 400 CCA batteries but that's marginal at best .

This whole thing in the winter cold, maybe just a case of low battery charge ~ I hope you understand to never quick charge a battery ~ it needs slow and gentle charging to be right as there's a chemical reaction going on inside it as the current is replaced .

As mentioned : a voltage test under load (whilst the starter is cranking or just clicking) .

I can go on about BOSCH starter failures but no point until you know what's what .

remember ; never use 1st./rev. to bump start any vehicle ! .

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-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

Over the years I have used many brands of aftermarket voltage regulators of this design. Overall I agree that the odds of getting one with problems are high. Many electrical aftermarket parts seemed to be produced having very low overall quality. One of my main issues with aftermarket regulators was low lifespan in service.


As for problems in general with the electrical system on these cars. You should keep in mind that a glow plug relay that comes on intermittently or constantly will mimic battery/alternator/starter problems. So it is just something you have to keep in the back of your mind.

New OEM voltage regulator is on it's way. I know it's a Hella on there now so for $35 I might as well replace it anyway.

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

Well ;

You ignored the single most important bit of advice here :

DO NOT BLINDLY THROW PARTS AT IT .

I hope you save that Hella brush holder ! .

The brushes *are* available if $pendy .

NAPA sells lots of different brushes, I keep thinking I'll try to match some up but no one stocks anything anymore.....

Please : go buy a voltmeter and TEST IT in the various ways mentioned before you get pi$$ed off and junk/sell the car in frustration .

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-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

Here is where I am at.

Let it sit all weekend. Fires up first crank everytime. No weak crank, nothing out of the ordinary. I didn't change or touch anything since it wouldn't start.

Looking under the hood. Fresh NAPA battery on 9/16. Ground on battery looks like it's been clean.



Starter from up top. Looks clean.



Starter from straight on. Looks shiny new. Also looks like someone even cleaned up all the wires.



So everything looks fine. Not sure where to go from here since it's not experiencing any problems.

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

It happened again.

Been using it as my daily driver the past month. Drive to work today, go out to the car two hours later to move it to a different spot. Wouldn't crank. Just the 'clunk' when you hit the key.

Called a co-worker out to pop-star it. Starts right up. Drive it for 30 seconds to a different parking spot. Fires up the next five tries just fine.

It has to be a bad spot on the damn starter.

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

Follow the red wires from the starter and battery's positive lead, they all join at a black plastic rectangular block , next time it doesn't want to crank try jumping the two bigger red wires with an unbent paper clip ~ if that works it's prolly the neutral safety switch that's out of adjustment or going bad .

__________________
-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

Car is a 4-speed manual.

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

DUH ! ~ you told me that (head smack) .

Still , you need to do this test because it positively tests of the solenoid is bad or there's another problem .

FWIW, that starter doesn't look like a high Dollar rebuild but the solenoid does look new .

BOSCH systems have several regular failure points in the starting system, why I said don't throw parts at it .

Doing that little jumper thing removes the starter from the car's electrical system pretty much .

I do see the yellow tape repairs and wonder if there's another issue but first the jumper test, O.K. ? .

I've been doing this for a living for close to fifty years , gotta take the proper steps in the proper order .

Keep at it and soon you'll figure out where the fault lies, replace / repair that problem and go back to happy motorvating .

__________________
-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

So jump the two solenoid posts together to see if it will crank?

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

Yes ~

There are THREE connections there so look closely and jumper the two red ones, they'll have 1.5MM red wires .

Remember to PUT IT IN NEUTRAL ! .

__________________
-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

I'd be willing to bet the solenoid is junk. Went through that in the SDL. Turn the key and hear the "clunk" under the hood, but no starter. Starter was a parts-house rebuild and the gorilla who rebuilt it packed the solenoid with really thick axle grease. Cleaned all that crap out and it's been flawless ever since. I realize the 61x engine isn't as easy to drop the starter out of as the 60x is, but it's worth checking since it looks like a rebuilt starter.

It's worth noting that if you're hearing the solenoid clunk, the circuitry between the switch and the solenoid is likely fine. The solenoid requires a good deal of current to pull in, a flaky NSS or ignition switch would usually prevent it from pulling in. That "clunk" does 2 things: 1: Engages the pinion with the flywheel. 2: Closes a set of heavy contacts to run the starter motor. #2 is usually where problems creep up.

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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. I can hear it clunk every time. So I know I am getting power there.

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

Sad today but fresher starter is a real possibility. It had to be a decent rebuild as there is a new solenoid. At the same time the original part is so expensive it might have a crap aftermarket solenoid installed. If you can locate the owner it may still be under warranty someplace.