So I got it off today. I believe that the primary issue in removing it was that the stud on the top of the unit was frozen into the top hole in the actuator motor. I soaked the whole thing with PB Blaster for a couple of days and sprayed as much as I could up into the gap that I had established as of yesterday. I did try to apply heat today but the location of that top stud made it difficult to access well. In the end the actuator finally broke free but it left the part of its mounting plate on that upper stud and the plate also broke off around the motor post (so I’m really glad that I had bought a replacement unit on eBay before starting the removal). These things seem to be made out of pig iron.
Anyway I got the old one out, completely smeared the mounting surface, studs and all mounting hardware with zinc anti-seize, and mounted the new one up and it works flawlessly.
I took the old one apart once I had it out and it is still a mystery to me as to why it wasn’t working properly. As you can see... no internal corrosion or stripped gears. Not a ton of grease but enough. The motor turned when engaged... it just did not seem to be able to disengage.
I can think of 3 possibilities at this point.
1- I don’t know if I broke the center plate when trying to remove the unit or if it might have already been broken or even just fractured prior to removal. 2- maybe the motor was turning into the engaged position strongly but had weakened in the reverse direction (as I understand it an electromagnet engages and the spring disengages the unit so maybe the spring got weak over time?)
3- I am far from the first owner and it has over 150k on it so who knows if somebody has had this off before? Perhaps the lever that the motor interacts with inside the 3rd member wasn’t clocked entirely properly?
#2 above seems like the most likely candidate to me.
So...having just done this I’d recommend the following:
Pre purchase a replacement unit or be ready to leave the 4runner on jack stands for a while if the pig iron motor mounting plate starts to disintegrate on removal.
2. PB Plaster & heat (thanks jrzee2000) for removal and zinc anti seize for reassembly.
3. Remember when reassembling to put both the motor and the lever inside your diff into the locked position (thanks kolelt)
Oh and do the grey (blue & red) wire mod before you start. It makes testing things out as you work dramatically simpler and now it’ll be easy to periodically activate the locker and keep it from freezing up again. I plan to do so weekly.
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