Headlight Cover Motor Repair

mgm1986

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Working on my '68 300. Waiting for some parts to come in to reassemble the brakes and heater box so I decided to look at the headlight cover motor. The wiring is essentially missing from the motor back so I will need to figure out where the wire runs. Looking at my FSM it looks like it should connect somewhere under the dash near the heater controls.

The motor does work, tested it up and down while still in the car. But the limiter doesn't work when opening and the wires are cut/frayed so I decided to pull it out and take a look. Seems the main plastic "cam" (The big white one) has a few teeth missing. I suspect this would prevent the motor from ever opening up the limiter switch, keeping the motor running when the headlights are turned on.

It seems like this may be a tough part to find so I decided to first attempt a repair using JB weld. Hopefully once the JB weld cures I can sand it down and shape new teeth on the plastic cam gear.

Headlight Cover Motor Disassembly.jpg
Cam gear with JB Weld.jpg
 
Working on my '68 300. Waiting for some parts to come in to reassemble the brakes and heater box so I decided to look at the headlight cover motor. The wiring is essentially missing from the motor back so I will need to figure out where the wire runs. Looking at my FSM it looks like it should connect somewhere under the dash near the heater controls.

The motor does work, tested it up and down while still in the car. But the limiter doesn't work when opening and the wires are cut/frayed so I decided to pull it out and take a look. Seems the main plastic "cam" (The big white one) has a few teeth missing. I suspect this would prevent the motor from ever opening up the limiter switch, keeping the motor running when the headlights are turned on.

It seems like this may be a tough part to find so I decided to first attempt a repair using JB weld. Hopefully once the JB weld cures I can sand it down and shape new teeth on the plastic cam gear.

View attachment 630809View attachment 630810
The repair that you have made may indeed correct the problem. You’re going to have to ensure that all of the parts are well lubed…
 
Thank you for that link, @Big_John . This would definitely be the best option. I will try to repair what I have before I drop $50 since there are plenty of other more pressing safety issues that need attention (money).
 
New gears purchased. I was optimistic my repair was going to work. I used JB Weld to add material back to the gear then carefully sanded it down to match the profile of the plastic teeth. The JB Weld immediately crumbled apart on the first test run turning the motor by hand. All those little bits would have just been floating around inside the motor likely causing more harm than a broken gear.

Worth a try but no luck this time. Back to the front brakes!
 
New gears purchased. I was optimistic my repair was going to work. I used JB Weld to add material back to the gear then carefully sanded it down to match the profile of the plastic teeth. The JB Weld immediately crumbled apart on the first test run turning the motor by hand. All those little bits would have just been floating around inside the motor likely causing more harm than a broken gear.

Worth a try but no luck this time. Back to the front brakes!
Yea, I kind of figured that is what would happen. JB Weld is great stuff, but just not strong enough for this. That motor is a pretty beefy piece with strong magnets for a lot of torque. When they work, they bang the doors open and closed, so the gear has to be pretty robust to take the shock.

One thing I've found is the bushing in the very bottom of the motor gets dry and the motor doesn't want to turn. I took mine apart, cleaned and greased it the bushing and cleaned up the commutator. It was a little challenging to put back together, but I seem to remember there was something internal to hold the brushes in place while you slipped the armature in, but I can't remember what it was.

Gunk on the commutator is the problem I'm finding in stuff like power window motors.
 
New gears installed and tested successfully with my power probe. Headlight covers open and close fully and the motor stops as expected. Had to make a new gasket as the old one looked suspect otherwise the kit worked perfectly.

Thanks again for everyones input on this!

Next I need to figure out the wiring through the firewall and where it connects under the dash.

Does anyone have pictures of where this relay is installed from the factory? There was a new relay in the parts box I just don't know where it mounts under the dash.

Picture of the relay I have
20231208_142341.jpg
 
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