An OM617 starter motor is for LIFE not just for Christmas!

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Christmas has come and gone and the current spate of cold weather has meant that most of us (in the northern hemisphere anyway) have probably been churning away for a little bit longer than normal...

Most fixing starter threads posted on this forum go through the process of removing a starter and then replacing it with another one – why? I don't know! Check out your old one first. If you haven't seen the insides before take a quick look through the photographs I've posted – I bet you'll be surprised how simple they are. I think it is worth while taking these things apart and assessing what needs to be done before junking them.

Before starting on a bit of a clean up of my starter motor I found some good information on vintagetest.net. In particular the following pdf file:-

http://www.vintagetest.net/chassis/elis78/V2I783032.pdf

Step one - take the starter motor off of your car – on a non-turbo engine just unbolt it and take it off – with a turbo have look through the wiki:-

http://www.peachparts.com/Wikka/OM617StarterMotor

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After removing the starter motor from the engine give it a wipe and start undoing the bits at the end.
Remove the wiring between the motor and the solenoid.



Remove the end cap that covers the end of armature axle.



Inside you'll find a rubber sealing ring...



...and a C clip that is used with several shims to set the axial end play of the armature axle shaft.

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Next undo the bolts that hold on the end cap...



...and if the cap is stubborn to remove use a puller.



Don't be tempted to pry this bit off. The main casing is steel and the cap is a nicely cast piece of aluminum alloy.
When you've got the cap off you will be able to see the commutator and the four brushes.



At the other end of the starter motor remove the nut and bolt that holds the actuating arm in place.



This actuating arm is the bit that gets pushed by the solenoid and engages the starter motor driving cog into the flywheel.

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Once you've got the actuating arm locating bolt out and the end cap off you can loosen the main outer sleeve. You might be able to pull it off – if not carefully persuade it with a screw driver blade (eeek be careful) – better still tap it with a rubber hammer!



You can now withdraw the mechanism that engages with the flywheel (the drive assembly) away from the nice aluminum alloy casting which also holds the solenoid.



I do like these castings! These Bosch starter motors are very well made – which is why it is a shame to junk them.
Take out the actuating arm and yoke.



You'll also find a rubber cover and a plate here.
You can now pull out the armature assembly away from the outer casing.



Inside the main casing you'll see four field coils.



To see how an electric motor works have a look here:-

http://en.wikipedia.org/wiki/Starter_motor

That's as far as I went – you can pull the drive assembly away from the armature – but mine was nice and clean – freely moving – so I left well alone. To see more on how to do this have a look in the pdf file – link posted above.

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To remove the solenoid you in principle need to remove three 40mm M5 screws. Mine were stuck and needed to be drilled out.



The solenoid comes apart just like this:-





Cleaning it up a bit

As my starter motor was fully functioning before I took it apart I just needed to clean it all up a bit. I used brake cleaner to degrease the commutator and I very very lightly rubbed it with a plastic scouring pad to clean it up a bit. You are not meant to use emery cloth or anything too aggressive here. You want a nice smooth surface so that the brushes don't snag and chip.



If you find a worn / scored commutator you can get it turned (on a lathe) so long as there is enough meat still on it. Any decent machine shop should be able to help you here.
I chose to posh my starter motor up a bit and stripped and repainted the outside surfaces. I used a self etching primer for the aluminum alloy parts followed by Eastwood's under hood black, and for the steel parts I used plain old POR15.
I cleaned the brushes with brake cleaner and cleaned the four coils in the main cover the same way. Avoid drenching the whole assembly in brake cleaner. You don't really want that hanging about inside the parts you are cleaning. Think “cleaning delicate tender wound” not “let's pressure wash this muck off of the face of the earth”.

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Once you've taken one apart it is quite easy to see how it all goes back together again. After cleaning and painting parts I greased up the drive assembly... (Please note Bosch recommends oil on all moving parts - it was my personal choice to use grease)



...attached the solenoid actuating arm and placed it into its housing.



I applied grease to the bearing surface here too. I believe these bearings are meant to be soaked in oil prior to insertion to the assembly – I decided to use grease – but you could try oil with the bearings in place. Good luck with that!

(Yet again - Please note Bosch recommends oil on all moving parts - it was my personal choice to use grease)

Next I fitted the bolt that holds the actuating arm in place...



...and put the metal cover and rubber top in place.

[funola]

Originally Posted by Army

To remove the solenoid you in principle need to remove three 40mm M5 screws. Mine were stuck and needed to be drilled out.

I learned another tip from a local rebuild shop. The 3 screws are loc-tighted in and that's why they are so prone to stripping. To make them come out easy, you first heat the bottom of the solenoid with a propane torch to soften the loc-tight.

[layback40]

Army,
You never took the gear off the end !!
Its a PITA to get off.
First push the collar towards the starter, then remove the spring wire ring, then slide it all off the end.
I had to replace the gear/clutch once.

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Originally Posted by layback40

Army,
You never took the gear off the end !!
Its a PITA to get off.
First push the collar towards the starter, then remove the spring wire ring, then slide it all off the end.
I had to replace the gear/clutch once.

Yep I chickened out because everything was working - it was as smooth and silky as a well known chocolate bar...

"Packing it in and packing it up
And sneaking away and buggering up
And chickening out and pissing about
Yes, bravely he is throwing in the sponge"

[JHZR2]

Great pictures and write-up. Thanks for that!

As I understand it, pulling the starter is a tough job, filled with possible issues... It would be neat to at least see the pictorial for how you reinstall it!

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Originally Posted by JHZR2

Great pictures and write-up. Thanks for that!

As I understand it, pulling the starter is a tough job, filled with possible issues... It would be neat to at least see the pictorial for how you reinstall it!

I'll pass that one to a OM617a owner - but check out the DIY section - number 21 says "Assembly is reverse of removal" (http://www.peachparts.com/Wikka/OM617StarterMotor)

Without the turbo fitted to the car it is a piece of cake... sorry turbo owners... but you just lean on in there hold it with one hand and screw in the bolts...

[Fulcrum525]

Your own photo approves of this post.






I have a 603 starter in my garage that went out a few years ago....I would imagine that the principles are basically the same as the 617 starter?


Thanks for the link as well.....now I want one of these
http://en.wikipedia.org/wiki/Starter_motor#Hydraulic_starter

[w123er]

I love this write-up.

The vintagetest.net site hosting the referenced Bosch starter pdf seems to have vanished. Tried archive.org without success but was able to locate it here:
http://vintage.mitchell1.com/PClubData/chassis/elis78/V2I783032.pdf

Just trying to give back a tiny little when I am able. Hope this helps someone.

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Originally Posted by w123er

I love this write-up.

The vintagetest.net site hosting the referenced Bosch starter pdf seems to have vanished. Tried archive.org without success but was able to locate it here:
http://vintage.mitchell1.com/PClubData/chassis/elis78/V2I783032.pdf

Just trying to give back a tiny little when I am able. Hope this helps someone.

Thank you very much for that - I'll ask the moderators to update the link

[hjoab]

Do you know the Part names and number (from Bosch)?
By the way, do you know the material (aluminium??) of the cast where the selenoide is fixed?
My starter broke there and I want to try soldering it back.