Idler Pulley Problem

[Paul94]

On my friends 94 GT we are having problems keeping the serpentine belt from coming off (almost off actually) at the power steering pulley. This started happening after we took off the underdrive pulleys and put the original stock pulleys back on. We have checked everything and read that the pulley tensioner or idler pulley along with belt size could be the issue. We changed them all but the belt still wants to ride over the power steering pulley. We bypassed the idler pulley and the belt ran true and never tried to jump the other pulleys. I have noticed that the idler pulley is not quite square with the alternator and power steering pulleys. I have 3 idler pulleys and all 3 are about the same. The power steering mount has never been removed or even loosened and the mounting surface shows no damage and the mounting bolt is straight. I have tried to get him a Motorcraft pulley but can't find them any more. My question is are the after market pulley poorly made or do I have another problem.
Thanks

 

[01yellercobra]

Is the crank pulley seated all the way? Which way is the belt being pulled? Towards or away from the engine? If its being pulled towards the engine you could always shim the idler pulley out and see what it does.

 

[Paul94]

the belt is moving in towards the engine on the power steering pulley. When I look straight down at the idler pulley you can see it leans a little in towards the engine on the drivers side. I looked at a friends 95 GT and his idler pulley is evenly mounted with no lean. The lean has me thinking crappy after market pulleys.

 

[ttocs]

put a straight edge on the side of the pulley and see if it lines up with the rest of them. Sounds like it does not but not sure why.

 

[dcm0123]

Could be junk pulley or maybe there is play in the mounting holes and you have to align it to make it straight. I assume you are talking about AC delete pulley which is next to PS pump.

Power steering pump pulleys are pressed on to the shaft. I believe they have to be pressed on a specific amount, no necessarily to a hard stop. Use a strait edge on PS pulley to make sure it lines up with crank pulley.

Have an 351W in mine. Had a lot of problems destroying belts until I bought an aftermarket billet aluminum tensioner pulley which had a flange on both sides. For some reason when engine was reved the belt would shift on the tensioner pulley then jump off the alternator pulley.

https://www.steeda.com/steeda-mustang-aluminum-tensioner-pulley-555-3325.html

 

[Paul94]

Update: I took 01yellercobra's advice and put a washer behind the idler pulley and the belt tracks true now. I don't know why put it is working now.
Thanks everyone.