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Last edited by CaliBenzDriver; Oct 13, 2025 at 03:30 AM.
Alright so, update time. I decided to go with the cleaning option today, first. I cleaned the entire starter and removed all the carbon on the inside and the grease. I reassembled it and greased where needed. But what I noticed is that the brushes on the motor are all the same and make VERY good contact on the rotor. And the brushes are pushing very good up against the rotor, the springs and carbon brushed all look just as compressed like new ones online, not one looks short at all. I thought maybe all the dust and dirt inside was causing some power-loss or electricity to get lost. Again, all cleaned thoroughly and tested the started by connecting it to a different battery directly and it spins up. Next I installed everything back in reverse order and tested it. First time and I immediately get the half crank as in the video, and second, and third. Then I connected my jumper pack to the booster points and it fired right up again. My friend thinks its some electrical issue within the car, but it doesn't explain why it always starts with a booster or when the engine has run and its warm or hot. Then it will always start, but now that its getting colder when i park my GL at work for the day and go to start 8h later it will give me the same BS again. It will start eventually if i push the Push-to-start button and keep holding it, where the car then proceeds to go through many attempts and quickly. And sometime after the 10-20th try it'll fire up like nothing. Im so frustrated, its making me want to sell it, even though I like the GL and the engine otherwise works like new minus one error (but that for later). Any more ideas on what It could be? Im looking at buying in the meantime a new starter and install it to see if the issue persists, if it doesn't then great! It was the starter all along, not sure why cause it looks good inside. If it doesn't then I am out of ideas. Someone please share any ideas they could have on why it keeps doing this. Again, it will start after 10-20 cranking cycles when holding the PTS button down, but when it ran and warmed up it will always start on the first try, probably due to the oil being warmed up and engine easier to crank. My starter brushed looked like this new one, with the carbon brushes in the same position and making perfect contact. Spring applying very good contact.
Alright so, update time. I decided to go with the cleaning option today, first. I cleaned the entire starter and removed all the carbon on the inside and the grease. I reassembled it and greased where needed. But what I noticed is that the brushes on the motor are all the same and make VERY good contact on the rotor. And the brushes are pushing very good up against the rotor, the springs and carbon brushed all look just as compressed like new ones online, not one looks short at all. I thought maybe all the dust and dirt inside was causing some power-loss or electricity to get lost. Again, all cleaned thoroughly and tested the started by connecting it to a different battery directly and it spins up. Next I installed everything back in reverse order and tested it. First time and I immediately get the half crank as in the video, and second, and third. Then I connected my jumper pack to the booster points and it fired right up again. My friend thinks its some electrical issue within the car, but it doesn't explain why it always starts with a booster or when the engine has run and its warm or hot. Then it will always start, but now that its getting colder when i park my GL at work for the day and go to start 8h later it will give me the same BS again. It will start eventually if i push the Push-to-start button and keep holding it, where the car then proceeds to go through many attempts and quickly. And sometime after the 10-20th try it'll fire up like nothing. Im so frustrated, its making me want to sell it, even though I like the GL and the engine otherwise works like new minus one error (but that for later). Any more ideas on what It could be? Im looking at buying in the meantime a new starter and install it to see if the issue persists, if it doesn't then great! It was the starter all along, not sure why cause it looks good inside. If it doesn't then I am out of ideas. Someone please share any ideas they could have on why it keeps doing this. Again, it will start after 10-20 cranking cycles when holding the PTS button down, but when it ran and warmed up it will always start on the first try, probably due to the oil being warmed up and engine easier to crank. My starter brushed looked like this new one, with the carbon brushes in the same position and making perfect contact. Spring applying very good contact.
Okay, let's abstract the starter condition and pretend this is a "known good unit", then what else could be happening to create a long crank on Diesel...
Suggest the local MB Diesel specialist to use factory procedures to then focus on troubleshooting theses standard items:
Diesel Glow-plug HEATER functions
both side of battery connections
the main chassis GND strap
The way "booster pack" reliably helps suggest this could be related to a "voltage drop" through oxidized (+ or -) connections.
Battery connection is good, not oxidized. The glow plugs work as they should. And it doesn't crank slow, it cranks good but doesn't give it a full turn. It only does the half cranks as in the video i posted earlier. I checked the + wire to the starter and its good, the GND strap is also good. And considering the Starter gets GND from the engine there cant be a bad connection there.
Battery connection is good, not oxidized.
The glow plugs work as they should.
And it doesn't crank slow,
it cranks good but doesn't give it a full turn. It only does the half cranks as in the video i posted earlier.
I checked the + wire to the starter and its good, the GND strap is also good.
And considering the Starter gets GND from the engine there cant be a bad connection there.
That is a lot of good progress items:
good glowplugs
normal not slow crank
clean power cables
The most revealing clue may be the half-turn crank... this begs to doublecheck the crank position sensor - Is the ECU setting a fault ?
Last edited by CaliBenzDriver; Oct 15, 2025 at 01:36 AM.
[size=16px]I replaced the starter with a new one from Amazon that I tested and it works. After installing and reasembling I went for a start and on the first try it gave me a half-crank again and did not start. It still does this every do often, but one thing I have noticed that If I get in the car and dont short press the PTS button but rather hold it down to start it always starts on the first time. Which now got me even more confused, as now I have not a clue as to what this could be.[/size]
[size=16px]Key gets detected, starter is good, battery is good. But it will start if I hold the button down, and can give a half-crank if I press the button (without holding it).[/size]
[size=16px]Anyone have any idea what this could be? This is the first time that I have had to hold down the PTS button on any of my mercedes to get it started. Usually its just a short press and the car does the rest.[/size]
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