My Wife complained of some hard starting issues so I checked the Charging Voltage and found I was getting 16-17 volts.

Typically that is either the fault of the Voltage Regulator or Alternator Diodes. However, the Battery itself can also cause the issue if it gets damaged internally.

I had no extra Voltage Regulator to swap in. So I decided to eliminate the Batter as the cause by connecting it to a Battery Charger. No overcharging (the charger had a digital display that shows the charging voltage) when connected to the Battery Charger and the Battery did not need charging either.

While I had the Mercedes Battery on the Charger I decided to start my Volvo Diesel which I did not insure last year just to run it. Once it was started I decided to check the charging voltage. Well it was also overcharging!

2 different vehicles overcharging at the same time is just too unlikely! And, I got one of my other Meters and that showed normal charging in both the Volvo and the Mercedes.

So it was a defective meter that was the cause of the supposed overcharging.

I had trouble getting the Mercedes started and there was no Glow Plug light going on. That light has stopped working for a year and then come back on all by itself and I had ignored it not working because the engine started normally.

The Glow Plug light had come back on like a year ago and had been starting normally. However, most of that year my Wife was driving.

This time it cranked a lot before starting and no Glow Plug Light. I had not had to change any Glow Plugs for over 10 years so it did not come to me right away that it could be the Glow Plugs.

When it finally dawned on me I checked with an Ohm Meter at the Glow Plug Wire Connector un-plugged from the Relay. And it showed 3 Glow Plugs with an open circuit.

Had to scrounge around till I found my box with the new Glow Plugs in it and fortunately I had 7 new Bosch ones (made in France as were the ones that were 10 years old).

When I reamed out the Glow Plug holes there was carbon but not massive amounts of it.
Since I had not done the job for awhile it felt a little tedious; I mean I was 10 years younger the last time I replaced any Glow Plugs.

I also installed a new Fuel Pressure Relief/Overflow Valve that I bought close to a year ago. Have not driven enough to notice any difference except is seems I idle a little faster but that is too subjective as I had not been driving the care for a long time as my Wife had it.

Back to the electrical stuff I am going to replace the Ground Cable at the Battery and remove and clean the contacts on the Ground Strap soon.

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84 300D, 82 Volvo 244Gl Diesel

Make a new zero gauge ground strap and make one to ground the alternator body

Ya, I have been meaning to ad some sort of ground cable to the alternator frame but have never done that.

While using a thicker gauge of cable won't hurt it won't be an improvement over the stock cable size.

When I rebuilt my Starter I was considering replacing the Positive cable and found that it was the original and had Mercedes Part number on a sleeve that was on it. I was also surmised at the diameter of the copper cable.
Note there is a pic in my thread of assorted cable diameters and some text comparing the Mercedes cable size.
What you will see is the actual size of the Mercedes stock cable is slightly less then 2 gauge. The actual wire core on the stock Mercedes Positive Cable is 1/4th of an inch.

From the first post in my thread the thread: "For some reason a Battery Cable Gauge is measured with the insulation on; see attached picture. Mine measured .410 outside diameter which is slightly smaller then 2 gauge."

In post number 3 you can see how thin the stock cable looks without the insulation on it.

What Gauge is a Stock 84 300D Battery Cable

So a Mercedes coming from the factory with a nice tight new engine came with cables that have a copper core of 1/4th inch that handled the amperage it took to crank a tight new engine.

On down the road it takes less amperage to rotate a worn Engine.

When I checked the Cranking Amperage on my own Engine; even with the glow plugs being on during cranking it was the same as the amperage it takes to crank a large V-8 gasoline engine.

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84 300D, 82 Volvo 244Gl Diesel

Better grounding can’t hurt, especially for the alternator.

For some reason, the grounding through the alternator body and chassis degrades over time, and prematurely kills alternators.

Grounding the battery -, motor to chassis, and alt to chassis with some beefy cables will put your mind at ease.

Rust of the Alternator bracket parts and what ever oxidation happens to aluminum decreases the grounding of the alternator.

I bought my Mercedes in 2007. Since then the only work done on the alternator has been bearing replacement and related to that I changed the Fan Belts with I got the car.

The Alternator had a rebuilt by Bosch North America sticker on it but the bearings inside of it had made in China on them.

Other than that I have had no Alternator issues I can remember dealing with. In 13 years I have replaced no Brushes, or Voltage Regulators.

I forgot to mention due to this fake over charging issue I ordered another Voltage regulator along with the new Glow Plugs. If for no other reason then to have another Voltage Regulator for for troubleshooting.

Where I live in CA has been in a drought condition for around 8 years now. Stuff like ground connection areas do not corroded much in dry weather even though I live not far from the Beach.

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84 300D, 82 Volvo 244Gl Diesel

Had a chuckle there.
Thanks for that.