Starter Spins But Won't Engage
 

I recently had starter problems on my 94 4runner after a 3.4 swap. I used the 3.4 started because it looked nicer. The starter would click but not turn over. I've had that problem before on other Toyota's. I pulled it out and the contacts were bad and covered in black gunk. I cleaned everything, replaced the copper contacts and put it back together. I tested it in my driveway and it fired right up a few times. But after I drove it for a while and shut it off, the starter quit engaging. The motor would spin free. I tried starting it a dozen times, hit it with a tire iron, and tried a few dozen more times with no luck. I finally got it to work by flipping the key to start as fast as i could until it finally caught. But then the starter stayed on and spinning for about 30 seconds until i started to back out of my parking spot.

If the starter spins, doesn't that mean the solenoid has moved forward and engaged? The contacts have to be touching with the plunger. Could I have put it back together wrong some how? Could the gears or clutch have gone bad in the nose of the starter? I'm going to pull it this weekend and try to do a full disassembly. If anyone has been through anything like this, I'm a little confused.

Did the clearances change with the starter swap? Sometimes, folks end up adjusting them with the use of shims. Sounds like the starter gear isnt catching the flywheel and needs a couple of shims...

I would compare the mounting points on both starters and check the starter gears.

I measured the spacing on the flywheel and the face of the starter. I dont have the 3.0 starter anymore. I sent it with the remains of the 3.0 I sold. The flywheel was about 3/4 inch from the opening and extended to 1 1/4 inch from the opening. I measure the starter while operating the solenoid by hand and it matched. I took it completely apart. The only things I could find wrong was there was a ton or moisture on the inside. The vent caps were missing and I had been driving through a foot or two of standing water in a flooded road. My guess is that something was shorted out inside. After I cleaned everything and regreased all the bearings and gears it works perfect. I also put in new rubber caps where the vents used to be.

Good find.