So im doing a head gasket on this 99 altima 2.4 never fully removed the timing chain or anything having to do with the lower half. Now with the motor fully reassembled and everything done I cant seem to get the alternator/ps belt to go on the idler pulley. I understand tension for the belt is done by the alternator and through everything we did, we never touched the idler pulley which sits in between the alt and the ps.

To better explain it because nobody understood until they looked and tried themselves. The pulley seems to have somehow 'sagged' a little. There isnt enough room for the belt to actually slide under the idler pulley. ( http://www.mediafire.com/?ifwdwdm6hcn5h2f ) There is brackets around the pulley both on top and bottom but we never touched any of those we dont think. And the pulley spins freely and is not binded or crooked in anyway without the belt on.

The belt will only go about half way on before its rubbing (between the pulley and the bracket coming off the block going to the ps pump) and even if you try to force it in there its gonna rub and get destroyed. Its not a new belt even so thats not a question. I guess im wondering if the idler pulley could have somehow dropped just a fraction of an inch, or is there possibly just a bunch of gunk back there, were gonna try gettin a pick in there and see if there is anything lodged in there but doesnt seem likely.

Just very dissapointing to tear down the head get it rebuilt only to be delayed by an alternator belt issue, anyone encountered this before or any ideas.

Figured it out, some old RTV had gotten back there, simple as that