For those of you that have experienced the Dreaded Click and No Start from you T1N Sprinter or newer chassis with the Bosch Starters I have a photo of the root cause of the problem.
I have been searching for a replacement solenoid for the Bosch 0-001-109-250 starter and finally found one on eBay. With that in mind I pulled the old solenoid that failed with 32,000 miles on it and chucked it up in my metal lathe. I used a parting tool to cut off the crimp that holds the plastic end cap with the terminals off to see if I could locate the problem.
What I found is that the copper strip and battery terminal contact is severely corroded and prevents the strip from providing any current to the motor terminal. That condition is what is causing the click of the solenoid but no starter cranking or motor spinning.
See attached photos that show the condition.
Certainly other vehicle or electrical conditions can cause a no start but this is likely the primary cause of the click and no start resulting in starter replacement.
Glenn 06 Navion 23H now with 38,600 miles
In case you are wondering the black lower terminal is the battery terminal with all the corrosion. The upper terminal is the motor terminal.