More alternator hell

Thanks to this forum I was able to install and wire my alternator correctly (many thanks!), but now every-time i start my truck the belt slips halfway off off the alternator pulley, but doesn't jump completely off. Im sure I've got all bolts on and tight and i checked that my serpentine belt routing is correct. Tensioner seems good, belt is tight.
Any experience with this?

Also, the alternator pulley looks in line with the others when i eyeball it. Hard to see in the pic but the belt is also slipping half off the idler as well, so it doesn't seem that the alternator is positioned incorrectly. The alternator spins fine also.

2005 Tacoma 6 cyl.

 

Doesn’t looks like your alternator was installed correctly or is the incorrect size.

 

Could be a bad tensioner bearing pushing the belt out?

 

Was the belt slipping off prior to changing alternator? If not, I think it’s pretty easy to diagnose what the cause is.

 

Is the alternator pully the same size as the old one. Is it a OEM ?

 

Did you replace the serpentine belt? If so is it the correct belt?

 

Rib count on all pulleys should match the belt rib count exactly. Make sure that belt
has the correct amount of ribs. You might be able to install some spacers or shims
in a pinch to get it aligned but thats just a band aide. Check with a straight edge.
or Ruler.

 

I think it most likely you have the incorrect serpentine belt if you replaced it or you got the wrong alternator.

 

In that pic, sure looks like the alt pulley is further out than the idler right next to it.

 

Where did you get the alternator and what brand is it?

 

Also double check to make sure belt is routed exactly per the diagram.

 

Do you have the original alternator to compare that the pulley is identical in size and that it sticks out the same amount?
When belt was off, did you you check all the pulleys for play and wear? Include the PS, AC, water pump, and tensioner pulley bearings when diagnosing.

 

This ^ I think you got the wrong alternator,go back and double check it against a new one from another auto parts store.

 

To me from the photo looks like a slight dip in the front of the alternator also the idler pulley
to the upper left of the alternator is extremely close to touching the alternator case.
Wrong alternator or mis assembly would be the culprit.

 

That was my first thought, wrong pulley.
I went out and looked at my '08 and it appears exactly the same as the pic.

 

Holy crap thanks a lot guys. Really appreciate the generosity here. I got it. After inspecting every inch of the serpentine i found that it was one 'groove' off on one of the pulleys that was difficult to see. this error accumulated across the assembly to produce what you saw in that picture. Feel like a dummy. Anyways, still have to do some voltage tests to verify that the wiring is correct but i think i might be finally able to drive my truck again. Thank a million everyone!

 

Glad you figured it out. It’s great this community is so generous with help and support. Let’s all remember how frustrating a repair simple or complex can sometimes be.

 

I've only had one vehicle to do this jump off the pulley belt thing. A Ford. Would always
slip the serpentine belt off one notch toward the front. It drove fine that way but would eat
the belt up in about 1000 miles. I took all the drive pulleys into close inspection.
I found the problem was the upper idler bearing was bad. No noise but loose when the belt
was off of it. So it was angled down when the belt tension was on it strong.
After idler replaced it (belt) never walked off again.

 

Either way, it’s good the belt didn’t come off.
With the stories I’ve heard here. When the belt comes off, it can (and has) gets sucked in behind the crank pulley. Which in turn takes out the front oil seal.

When I replaced my serpentine belt. I started the engine just long enough to shut it right back down.
Then inspected the belt. Just as OP did. Just in case there was a problem.

 

Good job.