OM603 Starter Motor Replacement Procedures

[ccooper]

I've just had the honor and privilege of replacing the starter motor in my 300SDL for the second time in three years, and I thought it would be nice to start giving something back to this forum. I've attached a PDF document outlining what I did in replacing the motor.

This is not a terribly difficult procedure and knowing how to do it could save lots of time and effort, especially as it relates to towing a non-starting car to a mechanic or dealer. I rate this a notch above an oil change as far as difficulty. It's not quite as easy as a fuel filter change, but a lot less difficult than replacing the center air vent vacuum pod in the W123 or W126.

Please give me any feedback about the document as I want it to be of value.

The document can be found at the following link since it exceeds the 73 kb limit set in the forum.

http://www.gbcnet.com/mercedes/docs/OM603%20Starter%20Motor%20Removal%20and%20Installation.pdf

Casey

[compress ignite]

The Remote (relay actuated) "Plug and Play" Starter activation is really a sharp
idea!

Thanks

[greg88]

I have a '93 300d with the 602 and your write-up was really helpful.

[LUVMBDiesels]

Great write up! Exactly what I needed

Thanks,
Joe

[Jeremy5848]

Nicely done, I have filed it away for future reference. The relay is a good idea, might someday save an ignition switch.

[dieseldiehard]

Nice writeup. But I wonder why you had to replace the starter in such a short time? Are you not using Bosch rebuilds? If the engine is good it should start quick (unless in really cold environments) and the starter will last decades.

[probear]

Kinda ironic timing from my point of view....As I wait for the parts store to call me with a new starter so I can go back out in the cold to R & R the starter on my 300SDL..........

Oh well.....at least the article confirmed the steps I thought were right....

[rektide]

If possible, more info on the Bosch relay would be good. The document cites,

I added a relay to the wire coming from the ignition switch

, but i dont know where/what the ignition switch is.

Also, I'm a little concerned about relaying the starter... arent there a couple hundreds of amps going through the starter? What kind of power is this Bosch relay (WR-1) intended to sustain?

[4x4_Welder]

The relay just goes between the ignition switch and the signal terminal on the starter. It's a great mod that allows the ignition switch to last quite a bit longer. Only the ~25amps that it takes to activate the solenoid goes through the relay.

[crashone]

I know this is an old thread but I needed to replace my starter on the 1987 300TD and this write was right on time. The OP has not posted here since 2008, if he was still active I would thank him personally. The best advice was how to work the starter out and back into the engine bay.

[JHZR2]

I know this is an old thread but the write up is still available.

Can anyone say how long it takes to do this removal job?

[vstech]

The sdl has pretty easy access...
It is a pita on a 190 or a 124, but with patience it is still doable from above.

Always remove the negative battery cable first..

[JHZR2]

Originally Posted by vstech

The sdl has pretty easy access...
It is a pita on a 190 or a 124, but with patience it is still doable from above.

Always remove the negative battery cable first..

Thanks!

This is a video of my symptom:

https://youtu.be/_DfkgoGw_1k?si=WMZx-J9s3vDP7bIg

Fingers crossed there are no flywheel issues…

[vstech]

Sounds like a starter not engaging the flywheel.
You might be able to open the starter, clean or replace the bendix and reinstall...

[JHZR2]

Originally Posted by vstech

Sounds like a starter not engaging the flywheel.
You might be able to open the starter, clean or replace the bendix and reinstall...

Sure hoping that’s the case. Kind of up in the air if I just buy a replacement, just to have just in case (I think it fits my 190d, 300d, and 350sd cars at least), or if I just take my chances removing and assessing first.