I have a 1980 300D with 190,000 miles. Noticed that it sounded like the starter was sluggish the other day. I thought perhaps the battery was weak. I parked it at my garage. The next day I tried to crank it over and it clicked once. I put a multi-meter on it, and it said 13 volts. I put a battery charger on it and it acted like it was fully charged. Then I noticed that it was having less of a charge. It would not start with the charger on in the 'start' mode. I removed the battery from the car. Multi-meter shows 12.7 volts. I replaced the battery, had just bought it a couple of month earlier when I bought the car.

I thought perhaps it was the starter stuck in the flex plate. Or perhaps the solenoid. Or perhaps the relay that is on the fender adjacent to the battery.

Without just replacing them, is there a handy way to test them on the car?

I have a multi-meter, but am not very skilled in their use. I know how to test voltage and connectivity. That's it.

Not sure if this matters, but I think of the glow plugs is bad. Before it stopped starting, for about a week prior, the glow plug indicator would flash for 1 minute after it started. I know that means that one or more are bad, but don't know if that could be causing this issue. Again, it does not turn over. Just makes one click and then nothing.

If there was already an article on this topic, forgive my ignorance. I did a search but could not find anything.

Durin

 

Take the Battery to have it charged and load tested.

If a Battery suffers some internal damage it can show good Voltage but not be able to carry the load; even a new Battery.
If your Battery is farily new you should have a Warranty on it and if it is no good they should replace it.

I had this happen to me but with an old Battery.
The Engine started fine; I stopped to get something to eat; went back to start the Engine and nothing happened (Manual Transmission).

I had a Multimeter in the Car and the Battery had normal Voltage.
I took a Wire to Jump the Starter Solenoid but no cranking and only a tiny spark.
I put the Wire a crossed the Battery Terminals and again only a tiny spark.

I installed a new Battery and the Engine started right up.

 

Remove and clean the Contact Ares of the Battery Ground Cable where it attches to the Body and the Engine to Body Ground Cable.
Make sure the Positive Calbe from the Battery to the Starter is making good contact and in good condtion (the Battery Cables can corrde inside, take a peek under the insulation).

In the picture is a Wire Terminal/Junction Block that the Turbocharged Models have is on the Fender Well infront of the Batter (US models).

If you connect a Remote Starter Switch or Jumper Wires (carful not to get burned) to where the Yellow Arrows Point the Starter Motor Should Crank. (If you battery and Battery Cable Connections and Grounds are good.)

If nothing still happens get a 2x4 or other suitable pice of wood and a Hammer. Put the 2x4 somewhere on the Starter that hitting the 2x4 might loosen the Solenoid if it is stuck.

If none of the above helps ther is a good chance it is a Starter issue.

The stock set up does not have a Starter Relay like lets say a Ford Car does.

 

Had the parts house replace the battery. I cleaned the mounting location for the negative terminal. Car started up. I'm not sure how fast the start motor should turn over the engine, my first diesel automobile, but it is faster than it was before. Thank you for the advice.

Durin