Starter motor re-build (with pics)
After my slight wiring issue, starting has been a bit of a lottery so today (after the off-roading event of last weekend) I decided to bite the bullet and buy a new starter motor. Mr Mercedes wanted £340 plus VAT so I decided to rebuild to one I had......
Removal was a bit of fun as I couldn't take up the ramp at work so I cracked off the two 10mm allen bolts securing the motor, (one screw terminal and the 17mm live feed), drove outside and dropped the motor off working on the floor. With props and exhausts in the way, I found the best attack was to use 3ft of extensions and undo it from somewhere near the middle of the vehicle.
After filling my eyes and ears with Devon and Dorsets finest clag, I had the motor free to work in the luxury of indoors. The end case is held on with two 10mm nuts and 2 slotted screws for the cover on the shaft.
On inspection, I found the commutator was badly glazed and the brushes had mushroomed. This is as a result of the motor staying engaged for some miles after the wiring issues.
I cleaned the comm using contact cleaner and 1200 wet and dry paper until the glaze was removed
I then used the dremel to remove the excess brush material, just like heel and toeing brake pads or shoes....
and for good measure, removed a little of the brush with wet and dry.
To re-fit the brushes, they had to have the tensioning spring released. I did this by bending the retaining tabs then pulled the brushes outward.
Then it was a simple case of pushing the brushes back in and bending the retaining tabs back in.
Simple.
I'll report back when it all goes horribly wrong :)
haha i like your attitude to the job
Good show Phil G.....
The real proper way would be turning the commutator on a lathe to get those copper segments perfect smooth and round again.
Have you done anything to the solenoid? It has the main starter motor contacts inside which can be damaged by arc burns and make only partial good contact - not sure you can get to it......
Another good idea is to check the big B+ cable to the battery and the engine ground strap for clean and tight connections - helps getting all available battery power to the starter.
Happy Trails
Hi Phil,
you probably know how to do this anyway but for anyone else I've just put on a couple of spots and wired them into a relay as normal but then I used a on/off/on switch with one connection to always live and the other to high beam. This way I have the choice of using just the spots or normal with high beam.
Yup, the previous pair were on with the high beams but these will be wired with a switch. The lower ones are fog lamps anyway. I will be fitting a second battery in the boot along with a removable box for my stove and the various bits I need for camping and recovery etc. I'm removing the jump seats as I don't need them. Always something to do. :)
I used to have four driving lights up on the roof rack and ran the wring along the rain gutter into the engine compartment.
The use of a relay (or two) is recommended and to run a ground wire as well.
My 1991 300GE was imported by Europa and after the US conversion didn't have the rear fog light anymore. So I use that light switch position to turn on the "flood lights"
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Cheers. I would normally skim it in a lathe but do not have the facilities to turn anything bigger than a motor from a radio controlled car. Solenoid was fine in operation so I didn't interfere just the motor had lost its oomph. Working like a goodun now. All the wiring was checked after the melting issue and made good where necessary. I had to fit a new battery negative terminal as those pressed metal ones aren't great. Next mission is to wire in my roof mounted spot lamps, just got 4 Hella Jumbo lamps which are about twice the size of the ones previously fitted. It's not complicated or exciting so I don't think I'll do a step by step unless anyone is interested?