R107 SL headlamp wiper electronic motor (coil type) repair

[SilverSaloon]

Hi

I've started to dismantle and try and fix my broken wash/wipe system on my 107.

I removed the whole unit from the car and went to test it with Red wire to Pos but the motor just appeared dead - no sound or anything. even if it was siezed i'd expect to hear something happening, so I decieded to dismantle the motor.

The motor seems a simple unit with a coil, magnet etc. Now, i know very little about electronics but there doesnt seem to be much to the unit apart from the resistor(?) - the little black box thing shown in the pic below:

The motor coil bit:

Any ideas from our electronic experts out there?

Any idea on where to get a replacement resistor thing? It has 'G65' marked on it along with '69J 017'. Its about 1cm in size.

it cant be that hard to fix the motor can it? The main cog thing isnt siezed and if you manually turn the coil when the rack is in position, the main cog slowly turns.

Thanks!!

Derek

 

[television]

That looks to be a suppressor and serves no use roll as far as I can see, but I would need to know how it is joined into the circuit, though looking again it is in series with a brush.

A better picture would help

 

[SilverSaloon]

That looks to be a suppressor and serves no use roll as far as I can see, but I would need to know how it is joined into the circuit, though looking again it is in series with a brush.

A better picture would help

there are two springy things that press against the "rack" bit of the motor that goes onto the main cog (thing that needs to spin)

one side is earthed to the main body of the motor. The other is connected to this supressor(?) and then that wire goes to the power source via the green wire you can see.

could i just connect 12v right up to the springy connector bit and earth the other one and the motor coil/magnetic thing should spin???

Merc charges £600 for this part (if you can even still get it) and it looks so simple with not much to go wrong so i hope i can just fix it?

thanks for your help Malcolm

 

[Myros]

the main trouble I've heard of

is the wiper gear tends to sieze up, damaging the motor by default by burning it out. You say yours doesn't appear to be burnt out, so it should work , in theory. Have you tested the winding for continuity/resistance? ( I defer to Malcolm on how you would actually do that)

 

[SilverSaloon]

i know very little about electronics, but how would i know if its burnt out or not? i thought the magnetic coil thing is a very simple mechanism that just spins with the current flow? i could well be wrong???

nothing is sized on this side of things - the actual wiper rods are siezed but they are currently disconnected from the motor. i didnt want to waste time unsiezing them until i know if the unit will be going back on the car or not, which depends on whether i can get the motor going.

the cog that the motor spins does spin if i turn the motor (the coil bit) by hand as it should.

when i purchased the car this was all still connected to 12v so i presume everytime the previous owner washed the screen with the lights on, it tried to move the siezed parts - i preseme maybe burning it out, but how would i know?

 

[Dec]

I will do this advice for £599 no VAT,

Clean everything with switch cleaner.

With a matchstick or cocktail stick clear out all the groves between each segment where the brushes rest.

Sand the curved ends of both brushes with fine sandpaper for 5 minutes, over the back of your finger to retain the curve.

Check that there is sufficient tension in the springs that hold the brushes to the commutator (worn bit)

Grease the worm corkscrew bit before reassemble.

Check for any bad connections.

Dec

 

[television]

Put the motor back to gether making sure that the carbon brushes move freely and connect up to 12 volt, if the motor does not run, short out the contacts on that black thing, and the motor should run, if it does not stick it all in a box and send it to me

 

[SilverSaloon]

Put the motor back to gether making sure that the carbon brushes move freely and connect up to 12 volt, if the motor does not run, short out the contacts on that black thing, and the motor should run, if it does not stick it all in a box and send it to me

thanks for the offer - i'll have another go with it tonight and report back

 

[SilverSaloon]

Thanks for everyone's help & advice on this. Last night I got it working. It basically just needed a good clean up as per the advice above.

I cleaned the grooves out and cleaned the surface from this:

to this:

I also cleaned the brushes with some sandpaper.

And now it just works! I intend to grease all the cogs etc.

I then dismantled the other parts of the unit to reveal a lot of siezed parts - basically the motor pushes a rod along the pipes that turn the cogs and turn the wipers.

Some pics of how it was inside the mechanisms:

and after a degrease, some of the parts ready to be re-assembed (with new grease):

 

[Dec]

That’s one for the DIY section, very useful, that treatment can work with a window motor as well as that is what I did with a dead window motor and got it working again.

Dec

 

[television]

Very good,do put some oil on the bronze bearings, just a drop each end

 

[SilverSaloon]

Very good,do put some oil on the bronze bearings, just a drop each end

bronze bearings?

 

[television]

bronze bearings?

Yes, they are the ones I mean, normally I would heat them while up submersed in oil, but the ladies do not like the smell in the house.

just a few drops will do

 

[SilverSaloon]

what i meant is where are they? i didnt notice any bearings

thanks

derek

 

[television]

the bearings are at each end of the shaft on the armature, one is in the center of the brush pack end plate ( in the center of the two carbon brushes) the other one is on the other end plate where the other end of the armature passes through

 

[wireman]

That black thing is a thermal overload cut out intended to prevent the motor bursting into flames if any thing goes seriously wrong, it is there for a purpose but maybe with vigilance about not letting the motor get jammed with power applied its OK to short it out. I have done this same trick on a rear window motor in the past.

 

[gaunty]

I have a problem with the headlamp washers and wipers on my 107 - neither work - I assume that this is the relay that "joins" the lighting and waher / wiper circuitry. I haven't yet done alot of work on the car and am finding my way round it - but what I haven't found is where all the relays are kept ! Can anyone help me locate these on an 89 car ?

 

[Dec]

There are some wiring diagrams here, not sure if your car is listed but the headlamp circuits seem similar in the various diagrams.

If an assistant activates the headlamp wipers (do the headlamps need to be on before the wiper will operate?) you should be able to hear the relay click under the open bonnet.

You could test each wiper motor if you can trace the wiring to each motor and disconnect it from the car electric’s and then run the motors directly from a battery charger.

Dec

 

[Myros]

the sidelights need to be on

and the wipe won't activate until you squirt. they then go to sleep for a few squirt cycles, and activate later on. I can't remember how many sleeps there are. or it might just be a time thing..

 

[gaunty]

Thanks for the advice and the link to the wiring diagrams - I followed 300SEL assuming it was close enough to 300SL for it to be the same, One stupid question though - where is the fuse and relay box located in the car !! (sorry to be asking such a basic question - but I can't find it !)