Starter Rejuvenation

[n/a]

I pulled the starter out of my 71 280sl today.  Planned on replacing the pinion drive, i.e. bendex unit, however, they sent me the wrong part (aaargh).  So, I'll be garaged the next few days, at least.

While I have the starter out, what places should be cleaned, greased, sprayed, etc. to rejuvinate it?  The brushes look pretty good.  Should I replace them anyway?  I don't see anything in the BBB (service manual) about working on the starter.  Does anyone have a diagram or other info?  Finally, the 2 smaller wires going to the solenoid were badly deteriorated and fell apart while I was removing the starter.  These wires appear to be the same color.  Can someone tell me which is the power terminal and which is ground on the solenoid.  Thanks for comments and suggestions,
Don

[ja17]

Hello Don,
The later heavy duty starter like in your car has two small wires going to the solenoid. The wires have different size ring terminals and screws so that they cannot be mixed up.
the wire with the smallest ring terminal should become "hot " when the ignition switch is turned to start position. The other small wire is the ballast resisitor bypass to aid starting.
There are several things I like to do when refreshing a starter; install new brushes, check the starter drive end bronze bushing and replace it if wear is detected, clean the commutator with a little fine emmery cloth, apply some grease to the bushings and other sliding surfaces.

If the commutator is very rough , you may have to send it out to be turned. Installing the brushes involves desoldering the old ones and soldering in the new.  

The bronze bushing can be driven out and a new one driven or pressed in. The internal diameter of the new bushing may need to be reamed back to size after installation. The brushes, and bushing are fairly inexpensive. starter parts can be ordered from a Bosch authorized distributor. I know NAPA can supply brushes also.

Joe Alexander
Blacklick, Ohio

[n/a]

Where should I apply some lithium grease?  Should I spray the internal parts with WD40?
Thanks,
Don

quote:Originally posted by ja17

Hello Don,
The later heavy duty starter like in your car has two small wires going to the solenoid. The wires have different size ring terminals and screws so that they cannot be mixed up.
the wire with the smallest ring terminal should become "hot " when the ignition switch is turned to start position. The other small wire is the ballast resisitor bypass to aid starting.
There are several things I like to do when refreshing a starter; install new brushes, check the starter drive end bronze bushing and replace it if wear is detected, clean the commutator with a little fine emmery cloth, apply some grease to the bushings and other sliding surfaces.

If the commutator is very rough , you may have to send it out to be turned. Installing the brushes involves desoldering the old ones and soldering in the new.  

The bronze bushing can be driven out and a new one driven or pressed in. The internal diameter of the new bushing may need to be reamed back to size after installation. The brushes, and bushing are fairly inexpensive. starter parts can be ordered from a Bosch authorized distributor. I know NAPA can supply brushes also.

Joe Alexander
Blacklick, Ohio

[ja17]

Hello Don,
The entire starter can be cleaned up with brake cleaner. Both ends of the armature shaft which fit into bushings should be lubed. I also apply a little grease to the worm gear and shaft the starter drive slides on. A small dab of grease can also be applied to the thrust shims at the rear, and the starter drive gear before installation. Do not get any lube on the brushes or commutator. WD40 is a good penetrant, but not a very good lubricant. Use white lithium grease of a synthetic bearing grease.

Joe Alexander
Blacklick, Ohio

[n/a]

Thanks for your help Joe.  Great advice, as usual!
Don

[ja17]

Hello Don,
You can check the basic function of the starter after re-assembly with a battery charger or battery cables and a battery. The charger should be at least 10 amps or use the jumper cables and battery.

Hook the ground cable to the housing of the starter. Touch the positive to the large LOWER lug of the solenoid. This is the one with the short fat wire which goes from the bottom of the solenoid to the starter. The starter motor should spin only. Next touch the point where the small ring terminal wire connected, the starter drive (bendex) should move forward on the shaft. Next clip the positive lead to the top solenoid lug (where the large positive cable in the car was connected). Now connect a jump between the large top solenoid connection and the small wire connection point. the starter drive should move forward and the starter motor will spin.
This confirms basic starter function but does cannot check starter load or starter drive for slippage.

Joe Alexander
Blacklick, Ohio