Here's a stumper:

I have a recurring starter problem with my 1984 Mercedes 300SD with 240,000 miles. Not battery or charging system – they have checked out fine repeatedly.

Problem occurs in reliable sequence as follows.

1. Car starts fine (12-15 starts)
2. Slight hesitation (1/10th sec.) at turn of ignition before starter motor spins (3-5 starts)
3. Pronounced hesitation (4/10ths sec) at turn of ignition before starter motor spins (1 starts)
4. No starter motor action at ignition key turn until key is turned repeatedly; usually cranks at key turn 12-15
5. The very next time, no starter action until key is turned 50 to 100 times
6. If car is left alone for an hour it may crank at next key turn but often will not crank for days
7. At some point, car will start fine and the entire sequence will be renewed

Here's what been done:

1. Neutral safety switch replaced
2. Ignition switch replaced
3. Starter motor replaced several times. This is the only guaranteed fix but last only 3-4 months.

Sound familar to anyone? Does this starter have seperate solenoid? If so, why aren't they sold by the folk who sell the starter?

if your starter is similiar to the one i replaced on my 83 240d, yes there is a separate solenoid. i purchased one for my application from the sponsors of this site. i did not use my head when i went to remove the soleniod from the starter. i forgot that i had an impact driver from my scooter days. using just a phillips head screw driver i was unable to break any of the screws loose. there are three. so i went and purchased a complete starter assembly. the solenoid with shipping, a bosch unit, was approximately $30. perhaps this will help until someone who is familiar with your specific model replies. and one other though. removing my starter was a snap. due in part to the fact that i did not have the front mounting bracket. previous service must have neglected to complete the job. did find the bracket at the dealer. i experienced similiar symptoms to those you posted and always had in the back of my mind it was a solenoid failure and not starter specific.

I have similar problems...with more symptoms.
Solenoid has not yet been brought up in my posts.

Question: When you turn your key all the way over, do you hear a 'click'? Is there any symptoms PRIOR to this happening?
I know yours is not draining your battery, but mine sometimes does, but most the time does exactly what you say...Starts eventually.

Here is a link to my posts:
300TDT won't start!

My God, Another problem

I will be following your posts as well. Hopefully we can both get our Diesels exorcisized!!

__________________
Current: '91 300TE 4MATIC 317k and climbing...
Former:
'81 300TD Wagon 168K "Tank"
'83 240D 216K 4spd manual "Da Bear" (aka best car ever)

"Never sweat the petty things...
and never pet the sweaty things."