W123 300TDT starter motor just spins fast

[300TD1982]

Hi all, I have a question with regard to my W123 300TDT (1984).



Recently, on two occasions I tried to start the engine, but the starter motor just spun fast without turning the engine over at all. Both times, I turned the ignition off, let the glow plugs fire again, and then started the car as normal.


I gather this is a faulty solenoid(?)



I have a spare starter motor, but I'm curious if it's possible to just replace the solenoid rather than the entire starter. (I have read that the starter motor is a bit of a bear to remove, so if a partial replacement is an option than I will consider it.)


Thanks in advance for any info you can provide. I couldn't own a Benz without this forum!

[tyl604]

Is this a station wagon?

[vwnate1]

Usually this indicates the sprag clutch in the Bendix is failing, not very expensive to replace .

[Sugar Bear]

Agree with clutch/Bendix drive is failing. When weak they usually act up in cold weather. Unfortunately it requires removal and disassembly of the starter and yes not an easy starter to change due to limited access to the top bolt.

Good luck!!!

[300TD1982]

Originally Posted by tyl604

Is this a station wagon?

Sure is! 5 cylinder turbo wagon, federal version.

[300TD1982]

Thanks VWNate1 and Sugar Bear. It has indeed been cold lately.
I have a used starter motor in the parts bin, but I think I'll try to get the local mechanic to install it.
I appreciate the help!

[vwnate1]

Be smart and replace the brushes and solenoid too, using only BOSCH or ECHLIN brand solenoid .

That top bolt is a PIA, I used abut 3' (maybe longer) of 1/2" drive extensions and the longest flex handle (misnomer : breaker bar) to break it loose first, then the rest of them came out without too much difficulty .

[Diesel911]

I rebuilt my Starter about 3 months ago and the screws that holed the Solenoid in are Phillips head and all 3 stripped out when I tried to remove them. Even with me using a hand impact wrench.
I had to drill out the heads to get the solenoid off.

So not being able to get the solenoid retaining screws to turn would be a major reason someone could not change the Solenoid on the vehicle.

I am not sure where people come up with the names for stuff that the do but the cutch mentioned on the Starter is commonly called an over running clutch.

That pinion/overrunning clutch on mine had a what looked like a Bosch part number on it.

[vwnate1]

Many are simply poorly educated and don't bother to learn the proper names of things .

[Shern]

FYI that “pinion gear” is a good $50 if you can even find one. And, by time you replace the solenoid, brushes and whatever else people tell you to replace, you’ve essentially purchased a new starter. This may not have always been the case, but in my experience (couple months ago) unless it’s in need of a cleaning and or perhaps a single easily sourced part, it’s simply not worth rebuilding.

[300TD1982]

Although I have a used starter motor here, I'm going the extra mile. I ordered a remanufactured starter and it'll be here in a few days. I'll have it installed next Monday.

Thanks for all the help!!!

[vwnate1]

Unless it was rebuilt by a BOSCH rebuilder, expect mediocre results and short life .

[Diseasel300]

When the starter in my BMW Touring took a dump, I priced repairing it vs. replacing it. New solenoid, brushes, bearings, and sprag clutch came out $13 more expensive than just buying a Bosch reman, and that was before the core fee refund. Unless you have the parts sitting around, you have a way to get parts at wholesale costs, or you "know a guy" you can get them from cheap, a genuine Bosch rebuild will very likely be the same cost or even cheaper. Considering the PITA factor of doing a starter motor (BMW M60 makes the OM617 seem elementary), it's a no-brainer which avenue I chose (and for less money).

[vwnate1]

As I keep saying :

You can put a horse in the river,

But only a pencil has lead .

[300TD1982]

Originally Posted by vwnate1

Unless it was rebuilt by a BOSCH rebuilder, expect mediocre results and short life .

I bought it from Rock Auto and they appear to be a Bosch rebuilder, but I am uncertain.