DIY Starter Rebuild? - PeachParts Mercedes-Benz Forum

robbsclassics · #1 06-13-2011, 02:46 PM

I've just searched on this site and the web for how to rebuild a starter. There are tons of videos on youtube, sites, parts for every other starter, but not for Benz. Is there anyone that has done a rebuild on a W123 (85 turbo if that matters)? Is there some reason that they are always replaced? I can get it rebuilt locally at a few places, so I know it can be done. I can even get a brush set at the local Autozone, but no info on a DIY.

Diesel911 · #2 06-13-2011, 03:10 PM

I have read a few threads that spoke of replacing the Brushes, Solenoid or Overrunning Clutch but there is nothing extremely detailed.

From the pics I have seen in is rather similar to a Delco Starter from the same era. The exception is that the Starter Solenoid has a heavy metal crimp on it so you cannot easily get in there and clean up the electrical contact areas.

Parts: A New Bosch Solenoid is around 1/2 the cost of a rebuilt Starter.
I do not think you can get the Brushes at the local Autozone; NAPA maybe.
It may be that NAPA would have the end cap Bearing/Bushing but I do not know.

The rest of the starter rebuild info you can find in one of those large Motors, Chilton, or Mitchell’s manuals. City Libraries have them on the shelf.

Stretch · #3 06-13-2011, 03:27 PM

Gentlemen =>

http://www.peachparts.com/Wikka/OM617StarterRebuild

robbsclassics · #4 06-13-2011, 03:43 PM

I was pricing starters when I found the brushes here. I'll check into the Delco starters. Just looked at mine off the car and it has the Bosh on it, but also a REMAN stamp in the casing, so I guess it was rebuilt at some point. I was starting the car for a long time and then the starter stopped working so I know I blew it. The only thing I don't know is what part is gone. When I bench test it I get sparks between the pos stud and solenoid screw, but no motor turning. Would this mean the solenoid is good, but the motor is dead? I'll look more in depth on rebuilding a Delco starter.

robbsclassics · #5 06-13-2011, 03:55 PM

Thanks Army, I just looked at that. I forgot to mention too, the starter was loose and only held on by one bolt. I can spin the motor with the gear, so that seems to be ok.

Stretch · #6 06-13-2011, 04:19 PM

I didn't do electrical testing on my starter motor but if you follow the link back to the thread funola did some checks on page 2...

I attempted a bit of electrical testing on my alternator

Refreshing the alternator on an OM617

If you've got any electrical testing information for alternators or starters I'd sure appreciate an update on either of the threads.

robbsclassics · #7 06-13-2011, 04:57 PM

From your pics I broke open the starter and found the problem. The brushes have a lot of meat on them, but the positive ones aren't attached to anything. Time to break out the solder gun. The commutator is pretty bad, but it looks like a little bit of steel wool will take care of it. (This would explain why the starter didn't seem to crank that fast.) I'm using some old gas to clean things up, but I'll electrical cleaner to finish up. I think I should be in good shape then. So...it looks like I won't need to have specs after all. That and the fact that my multimeter battery is dead....

leathermang · #8 06-13-2011, 06:06 PM

Do not use steel wool anywhere in there..
Do not use wet and dry sandpaper either...
IF you can find a drill large enough the easy way to fix the commutator is to chuck it upright and pull with sand paper wrapped around it... gently.... do not use anything to push on it... like fingers or wood to speed up the process... let the sandpaper do the work...
Air clean all that afterwards of course...

Use Flint Sandpaper on the commutator unless you have a way to chuck it in a lathe... then still good method to use Flint sandpaper strip wrapped around it and turn it on.. only take enough to make it nice and smooth.. THEN carefully take out the mica between the copper.. just so it is below the copper top line...

When you put it back together... be sure to use red locktite on the little screws on the end which hold the holder for those brushes... that can loosen over the years causing intermittent starter problems... and be hard to find.... That was what was wrong with mine... those brushes are HUSKY !!! LOL

Diesel911 · #9 06-13-2011, 06:51 PM

Quote:

Originally Posted by robbsclassics

I was pricing starters when I found the brushes here. I'll check into the Delco starters. Just looked at mine off the car and it has the Bosh on it, but also a REMAN stamp in the casing, so I guess it was rebuilt at some point. I was starting the car for a long time and then the starter stopped working so I know I blew it. The only thing I don't know is what part is gone. When I bench test it I get sparks between the pos stud and solenoid screw, but no motor turning. Would this mean the solenoid is good, but the motor is dead? I'll look more in depth on rebuilding a Delco starter.

I only ment that the Mercedes Starter worked similar and had parts similar to the DELCO Starters made at about the same time. And, that the repair would be similar. There is no direct crossover of parts.

I have no knowlege that DELCO rebuilds the Mercedes Starters.

In the below pic if you disconnect the Cables where the Blue and Green Arrows point you will isolate the Solenoid.
Apply + current to the smalle terminal (red line) and ground to the body of the Starter (if still on the Engine it is already grounded).

If the Solenoid does not function as above there is a real good chance it is no good. However, get a piece of Wood and try beating on it some to see if it jars something loose.
(The sparking issue you were speaking of does sound like there is a short circuit somewhere.)

Like I said I believe one of the Thick Hard Covered Motors Manuals would tell you how to trouble shoot the Solenoid.

layback40 · #10 06-13-2011, 10:42 PM

Quote:

Originally Posted by leathermang

Do not use steel wool anywhere in there..
Do not use wet and dry sandpaper either...
IF you can find a drill large enough the easy way to fix the commutator is to chuck it upright and pull with sand paper wrapped around it... gently.... do not use anything to push on it... like fingers or wood to speed up the process... let the sandpaper do the work...
Air clean all that afterwards of course...

Use Flint Sandpaper on the commutator unless you have a way to chuck it in a lathe... then still good method to use Flint sandpaper strip wrapped around it and turn it on.. only take enough to make it nice and smooth.. THEN carefully take out the mica between the copper.. just so it is below the copper top line...

When you put it back together... be sure to use red locktite on the little screws on the end which hold the holder for those brushes... that can loosen over the years causing intermittent starter problems... and be hard to find.... That was what was wrong with mine... those brushes are HUSKY !!! LOL

X2
This description is right !

One more thing is to make sure you clean the surfaces that the brush holder contacts the alloy back casting well. As its an alloy to steel contact its bad for poor contact. Also around the rim of the alloy casting where it contacts the body (field ) of the starter. You need good electrical contact in these areas as they see full starter current.

robbsclassics · #11 06-13-2011, 11:02 PM

Quote:

Originally Posted by leathermang

Do not use steel wool anywhere in there..
Do not use wet and dry sandpaper either...

Do'h, I did exactly this as I didn't see this in time. I see now why you say no steel wool. It stuck to everything and I spent an hour getting it all off. Well...I know what NOT to do next time. The starter works good now at least.

Quote:

Originally Posted by leathermang

When you put it back together... be sure to use red locktite on the little screws on the end which hold the holder for those brushes... that can loosen over the years causing intermittent starter problems... and be hard to find.... That was what was wrong with mine... those brushes are HUSKY !!! LOL

Will do. I just have to get a bushing and some washers tomorrow, so its just put together to test now.

robbsclassics · #12 06-13-2011, 11:09 PM

Quote:

Originally Posted by Diesel911

I only ment that the Mercedes Starter worked similar and had parts similar to the DELCO Starters made at about the same time. And, that the repair would be similar. There is no direct crossover of parts.

I have no knowlege that DELCO rebuilds the Mercedes Starters.

In the below pic if you disconnect the Cables where the Blue and Green Arrows point you will isolate the Solenoid.
Apply + current to the smalle terminal (red line) and ground to the body of the Starter (if still on the Engine it is already grounded).

If the Solenoid does not function as above there is a real good chance it is no good. However, get a piece of Wood and try beating on it some to see if it jars something loose.
(The sparking issue you were speaking of does sound like there is a short circuit somewhere.)

I know what you were saying, I just wanted to see some pics/vids and walk throughs with a starter that was similar so I knew what to expect before I got into mine.

I also got the starter working, tested it out on the ground with jumpers. So the solenoid is fine, which is one less thing to worry about. Now I just have to wait untill tomorrow for the bushing and seeing what I have for washers/spacers.

leathermang · #13 06-13-2011, 11:28 PM

Quote:

Originally Posted by robbsclassics

Do'h, I did exactly this as I didn't see this in time. I see now why you say no steel wool. It stuck to everything and I spent an hour getting it all off..

LOL. I imagine it was hard since there had to be some residual magnetism.... EEEKKKK....

IT is really good policy to post PLANNED actions... then leave enough time so someone can ' wave you off ' if you are going down the wrong path...
But this made more entertaining reading and others will remember it better.... at your expense of course....

robbsclassics · #14 06-14-2011, 06:02 PM

Quote:

Originally Posted by leathermang

LOL. I imagine it was hard since there had to be some residual magnetism.... EEEKKKK....

IT is really good policy to post PLANNED actions... then leave enough time so someone can ' wave you off ' if you are going down the wrong path...
But this made more entertaining reading and others will remember it better.... at your expense of course....

Yep...it really sucked getting all those steel hairs cleaned out. I know I learned from my mistake, and I hope others will find this thread if they are thinking of doing a rebuild. After I got it working I took it to a local alt and starter rebuilder and he gave me a new back plate and bronze bushing for FREE. He said the bushing on the other end is bad and the gear was really loose, but he can get all the parts I need. If I ordered them all new it would have cost about $40-$50 I think. Just a heads up for all the DIYers out there to save $100-$200 on a rebuild (and know its done right). I found out that my starter is basically an original Bosch starter that was rebuilt at low quality at some point. Another heads up to people out there. You may have an original looking starter that has cheap insides.

Diesel911 · #15 06-14-2011, 07:28 PM

Quote:

Originally Posted by robbsclassics

Yep...it really sucked getting all those steel hairs cleaned out. I know I learned from my mistake, and I hope others will find this thread if they are thinking of doing a rebuild. After I got it working I took it to a local alt and starter rebuilder and he gave me a new back plate and bronze bushing for FREE. He said the bushing on the other end is bad and the gear was really loose, but he can get all the parts I need. If I ordered them all new it would have cost about $40-$50 I think. Just a heads up for all the DIYers out there to save $100-$200 on a rebuild (and know its done right). I found out that my starter is basically an original Bosch starter that was rebuilt at low quality at some point. Another heads up to people out there. You may have an original looking starter that has cheap insides.

Did the shop Guy say what the cost of a real Bosch Solenoid is.

Comment on rebuilt stuff.
The front bearing on my Alternator went bad several years ago. The Alternator had a Rebuilt By Bosch North America sticker on it.

The no good bearing I pulled from it was made in "China".

BOSCH is creeping over to the "Dark Side".