Think I solved it.

I pop started it again because nothing was going to be able to jump it.

Once I got it started and drove it around I put a load tester on it. 12.4 with the lights on.. 12.6-12.7 without the lights. So I got the hammer out and put the end on the alternator belt to ''tighten'' it while running. Shot right up to 12.8.

So sounds like I have a loose/worn alternator belt or just a bad alternator. Voltage regulator is new. So that's out. I'm going to change the belt and tighten it and see if that fixes my problem.

I think the original no start was just not enough juice to even spin the starter.

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

This statement:

And this statement:

Don't agree with each other.

You've tried several times to jump start the car and failed each time. That points to a starter problem, not a battery / alternator problem.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

? Seriously / .

No one here knows basic starter teting ? .

Look at the front end of the solenoid, there are two large copper nuts ~ jumoer across them and the starter motor should *instantly* (not wind up to speed) begin to spin fast , not cranking the engine .

If it Doesn't either the battery is dead/low charge or the starter is needing service .

If it spins right up , try jumpering the thick red wire to the upper large nut, this will bypass the entire electrical system and force the starter to operate and crank the engine .

FWIW, batteries often die without warning so either get a good jump with real jumper cables, not those shyte 4Ga. ones everyone carries or an analog voltmeter and see what the battery shows when the start's load is applied to it .

How you diagnose this will affect the co$t and reliability of the repairs you do .

__________________
-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

The starter just clicking was only the problem the first time it didn't start. I've started it a dozen times today since without issue.

I see. It's a HELLA on there now. I assume the OEM Mercedes voltage regulator is Bosch? I can buy an OEM one for literally 75 cents more than the Bosch one.

I don't think anything will jump start these cars unless it's massive. My little 375 jump pack won't make a difference and I had a Jeep Cherokee try to jump me this morning and it did nothing. It was barely start the crank and didn't have enough juice to even think about cranking.

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

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 ! .

__________________
-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.

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