280SE 3.5 intermittent starter problem (M116 engine)

[rutger kohler]

Hi my care above has an internittent starter problem.  About every 5th time i switch the ignition key over to starter, the starter doesn't engage,  it is not a low battery charge as if the car is left for 10 minutes it will turn over and start.  There is not the clunk sound indicating a low battey charge, but a whirring sound.

I am thinking maybe the starter solenoid contact might be worn, or the starter commutator area might need machining; or the carbon brushes need replacing.  Any ideas appreciated before I start tearing things down

[WRe]

Hi,
in most cases the starter solenoid is worn - check the contacts - or the cabling is rusty or faulty. I would check this first.
What happens when you turn on lights and other electric consumers and try to start?
Get the lights darker - means that's something wrong with the starter motor -
or do they stay bright - means that there is no current flow, no contacts.
...WRe

[Cees Klumper]

In my car it was the ignition switch that slowly but surely went out, so that is another possibility.

[ja17]

Since the starter spins (whirls}, it is most likely that the starter drive is bad. It is like a ratcheting mechanism which will spin when the ratchet mechanism no longer holds. With this problem it is usually worse when the engine is cold. Looks like a starter rebuild is in your future.

[dirkbalter]

I have the same problem but a lot less frequent. Once in a while, it doesn’t engage and I hear it spinning. As soon the gear stops spinning, I try again and it will engage and start. Considering a starter is relatively inexpensive, I already bought a starter, ready to be switched if it gets any worse. Every 5 th time is a lot and you may want to take a look at starters soon.

Probably not feasible for you but here is where I got mine.
https://www.rmeuropean.com/Products/002151710188-MFG14-V5739.aspx

[rutger kohler]

Hi, thanks for that, all very helpful, will look at all areas.  Can anyone tell me if the starter mmotor for M116 engine is the same as the M130 engine starter plse?

[WRe]

Hi,
these starters fit in several models: 107-109,111,113-116,123.
There are also lighter models available: https://www.sl113.org/forums/index.php?topic=21743.0;all.
...WRe

[stickandrudderman]

It could also be that the teeth on the ring gear are worn and so not being caught by the starter motor.
If, when this happens, you can turn the engine over by hand from the alternator, PAS pump or even crank pulley and then the problem is immediately resolved then you have a worn ring gear which means removal of transmission.
(If the car is manual transmission you can simply put it in gear (IGN OFF!) with the park brake off and rock the car to rotate the engine from its rest position).