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Possible to install serpentine belt wrong?

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Odd question i know but I did my OFHG this past weekend. Was running OK and did maybe 100 miles this week. Was driving into town and saw the battery like come on a couple times. Turned off the radio and no more light. On the way home I got the yellow caution indicator(but not the battery light) and then the ABS light would come and go. Dropped off my carpool and made it home.

The belt was on and alternator turning when I popped the hood. Turned the car off. I checked to see if the cable was still on the back of the alternator but was hard to see. (When i reassembled the other day the metal clip for the plug with wires had fallen into the abyss so I put it all back together without it.)

I checked the oil which was a low. Put in half a quart or so. Went to start the car and nothing except dash lights.

The battery is only a couple months old. Is it possible to install the belt wrong? I used a T50 to de-tension the belt while putting the top bolt of the alternator in. That pulley is on a cam. The belt isn't that tight but not loos either. If the Alt is spinning it should be charging. (?)

Thoughts?
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Yes it's possible to put it on wrong. I used the picture from the Bentley manual to see how to put it on; it was pretty clear.

The belt should feel VERY tight. If its not, it could still be spinning the alternator, but not enough to charge properly.
It was tight enough to not slip off the flat roller (tensioner). What is the last part that get's insatlled? The top bolt of the alternator?
Tight enough isn't good enough. You should need to move the tensioner a few inches to make it fit, especially if you put a new belt on. I used an 18" breaker bar with the proper socket on the end to move mine. A ratchet of typical length was not adequate to get the torque needed to move it.

Also, if your pulleys and tensioner are original after 11 years, you will want to replace all of them ASAP. At about 68k miles, mine were showing signs of wear. They should not spin so freely that you can get a continuous spin with minimal effort. This indicates the pre-packed grease has dried out. They are cheap insurance and very easy to replace.
I was able to move it using my torque wrench. It doesn't move that far but was enough for me to get the bolt back in the top of the alternator and tighten it up.
I was thinking that maybe that should be tight already and loosen the left pulley, flip the belt on and then tighten? Was just looking for which part is the last that is loose.
Everything should be on and tight, then release the tension on the tensioner pulley and put on the belt. If you put on the belt and then tried to take up slack by tightening the alternator, you probably didn't get the belt tight enough.

I would loosen everything, remove the belt, tighten the alternator in place, tighten anything else you may have had to move, then install the belt by releasing the tension on the tensioner pulley.
I was able to move it using my torque wrench. It doesn't move that far but was enough for me to get the bolt back in the top of the alternator and tighten it up.
I was thinking that maybe that should be tight already and loosen the left pulley, flip the belt on and then tighten? Was just looking for which part is the last that is loose.
Thanks for replying. That was my first approach and couldn't get the belt on. When releasing the tension it moves the pulley about 1/2" and looking at the mechanism that makes sense. Should i loosen the left pulley too? Doesn't seem like I should have too.
Went out and the belt was over the top of that pulley instead of below. Tricky little setup.
Just saw this, yeah, it is kind of a pain. I feel for you, I had to stare at the diagram at the Bentley for a few minutes, as well as make some sketches of the car before I took the belt off when I was doing mine.
Went out and the belt was over the top of that pulley instead of below. Tricky little setup.
Can't believe I went 100 miles like that. Used a plastic door panel trim tool to help me slide it on. Would be easier with 3 hands. :)
Now lets hope when it warms up a little it will start.
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