Repairing a Merc starter, what's all to it?

[hotrod53]

My '77 Merc 500 starter gear has seen better days, it also occasionally sounds like the bearings could stand a little grease. From time to time it seems not to stay engaged as long as it should, I cleaned and lubed the shaft which helped somewhat.

I'm usually not afraid of starters, I have built and rebuilt auto starters and alternators before. I have a couple of questions:

* Can I just remove the nut to get the bendix off and replace it and do I need a puller?
* If I pull it apart, is anything going to fly apart?
* How do I get the brushes back in? History tells me that I will somehow have to hold the brushes out while reinstalling the armature.

 

[merc850]

Re: Repairing a Merc starter, what's all to it?

Here's an exploded view from the manual

and the second page shows the tool for installing the brushes, I made one out of an old CD drive case
- works great

 

[j_martin]

Re: Repairing a Merc starter, what's all to it?

They're pretty easy to work on. Just remember they're a permanent magnet motor, so if there's any steel grinder dust within 30 feet of it, it'll stick to it. He!! to get off.

Takes a tin tool, diagrammed above, to load the brushes.

If the armature needs to be cut back because it's badly scored, any good starter shop should be able to do it in about 5 minutes.

 

[hotrod53]

Re: Repairing a Merc starter, what's all to it?

Fantastic info gentlemen, thanks. Looks like there are no roller bearings, just sleve bearings, I think a finger full of grease will go a long way to making it more reliable. I may be losing starter RPM due to lack of lubrication.

 

[Chris1956]

Re: Repairing a Merc starter, what's all to it?

I have never seen a starter with bearings. All they ever have is bushings. Calling them sleeve bearings is kind...

Clean up the commutator with fine sandpaper. Scrape between the copper parts of the commutator to clear any possible shorts. A little bit of grease on each bushing should work. Inspect the brushes for bad wiring and for cracks, chunks missing etc.