starter won't spin

[w123amg]

I did search but couldn't find an exact answer.
On one of my benzes starter would work once in a while.
when I would turn the key, I would just hear relay clicking by the driver's fender and I would have to do it for good minute to get the starter to spin.
On another benz that I have starter worked fine every time.
When I swapped it, it did the same thing on the first car, just relay clicking.
So i put jumper cables right on the starter while it's in the car. positive on the small wire and neg on the ground wire of the car - nothing happens, just relay clicking.
I pull starter out, put positive on that small wire and neg on the bracket for the mounting bolt - the gear engages but won't spin. Got another starter from the junk yard - when applied power to it while it's outside of the car - engages but won't spin. I have tested starters before and all of them spin after engaging. Is mercedes different? is it not suposed to sping while not mounted? should i supply positive or neg to big bolt on the starter, that normally has wire going onto it? or i have 3 bad starters?
thank you.

[MB-Owner-in-ind]

Originally Posted by w123amg

I did search but couldn't find an exact answer.
On one of my benzes starter would work once in a while.
when I would turn the key, I would just hear relay clicking by the driver's fender and I would have to do it for good minute to get the starter to spin.
On another benz that I have starter worked fine every time.
When I swapped it, it did the same thing on the first car, just relay clicking.
So i put jumper cables right on the starter while it's in the car. positive on the small wire and neg on the ground wire of the car - nothing happens, just relay clicking.
I pull starter out, put positive on that small wire and neg on the bracket for the mounting bolt - the gear engages but won't spin. Got another starter from the junk yard - when applied power to it while it's outside of the car - engages but won't spin. I have tested starters before and all of them spin after engaging. Is mercedes different? is it not suposed to sping while not mounted? should i supply positive or neg to big bolt on the starter, that normally has wire going onto it? or i have 3 bad starters?
thank you.

You don't say what the cars are but I will take a stab at the problem. From what I am reading I would say the solenoid is bad.

[w123amg]

83 300td both of them

[SD Blue]

From your description, you are supplying 12v to the solenoid (small terminal) but not to the starter (larger terminal) therefore it won't spin. As in the car, the large batt. cable is connected to the large terminal then the key switches 12v to the solenoid.

CAUTION! This starter has very high torque and would be a good idea to secure well, such as in a vise, before attempting this.

[w123amg]

all of them work fine, thank you SD blue.
what could be a problem? is there a relay for starter that is clicking by the driver's fender?

[whunter]

Originally Posted by w123amg

all of them work fine, thank you SD blue.
what could be a problem? is there a relay for starter that is clicking by the driver's fender?

That is the glow plug relay.

[whunter]

Originally Posted by w123amg

I did search but couldn't find an exact answer.
On one of my benzes starter would work once in a while.
when I would turn the key, I would just hear relay clicking by the driver's fender and I would have to do it for good minute to get the starter to spin.
On another benz that I have starter worked fine every time.
When I swapped it, it did the same thing on the first car, just relay clicking.
So i put jumper cables right on the starter while it's in the car. positive on the small wire and neg on the ground wire of the car - nothing happens, just relay clicking.
I pull starter out, put positive on that small wire and neg on the bracket for the mounting bolt - the gear engages but won't spin. Got another starter from the junk yard - when applied power to it while it's outside of the car - engages but won't spin. I have tested starters before and all of them spin after engaging. Is mercedes different? is it not suposed to sping while not mounted? should i supply positive or neg to big bolt on the starter, that normally has wire going onto it? or i have 3 bad starters?
thank you.

Sounds like a failed NSS = Neutral Safety Switch on transmission, a very easy DIY.
Engine to body ground = connect a jumper cable from engine block to battery ground, if it starts you replace the factory ground cable.

Broken Neutral Safety Switch and replacing shifter bushings
http://www.peachparts.com/shopforum/showthread.php?p=646647#post646647


You can NOT test a diesel starter the way you are trying to, AMP draw test is what you need.
FYI:
Attached is a graphic of how to power the starter.
Danger:
extreme torque = it can break your head/leg/arm/hand, if not secured correctly.

[kmaysob]

Originally Posted by SD Blue

From your description, you are supplying 12v to the solenoid (small terminal) but not to the starter (larger terminal) therefore it won't spin. As in the car, the large batt. cable is connected to the large terminal then the key switches 12v to the solenoid.

CAUTION! This starter has very high torque and would be a good idea to secure well, such as in a vise, before attempting this.

that is correct. was the starter you have tested before out of a ford? most but not all fords have the solenoid on the fender(some have both one on the fender and one on the starter. mb has the solenoid on the starter.