I changed the alternator on my 2003 silverado 1500. how do I loose the belt to get it back on the pulley.

It could be a pulley, sometimes a worn belt will do that. Check the idler pulley, tensioner pulley, and alternator pulley, then check all the rest. If an alternator bearing is going bad, it may leave you stranded someday.

Hi: !st Thing you need to do is disconnect your negative battery cable to prevent more damage.If i'm understanding you Right you Took the Wiring off the Alternator.Or did you Remove the Mounting Bolts? Here Goes Disconnect Battery, Loosen the Bolt on the Alternator Adjuster Bracket, This will give you Some Slack in the Belt ,BUT Locate the Belt Tensioner take a Breaker Bar or The Correct Size Boxed in Wrench or use a Ratchet and Socket. The Tension Is Spring Loaded to Keep Your Belt From Coming OFF. Your Belt Runs Probally Everything like your Alternator ,Water Pump,A/C Compressor,Power Steering So On. So Until you Take the Belt Either OFF or Just Release the Tension on the Belt,I'm Sure if you Have Removed All mounting Bolts and Your Wires to The Alternator, Your Alternator Will Come on Out with a Little Light Effert. Be Sure You Watch How Eveything Comes Off Cause You'll Have To Reverse the Way you Took It Off To Put it Back Together. Be Sure You Look At the Belt Routing Diagram Which is on either your Cross bar By The Radiator. Its Say Belt Routing Diagram. Hope This Gets you Going It Should.If You Follow These Instructions. Please Let Me Know how My Advice Helped You By Voting And Also You Can Send me A Message on FIXYA. From The WYOCWBOY

its right above the crankshaft pulley,it is smooth and you will see the ribs of the belt because the smooth side of belt is on this smooth pulley

If it's a v8 then when looking at the engine the top left pulley has a 15mm bolt holding the pulley on. Use an endwrench and move/pull it to the drivers side of the truck!

if you just changed the alternator you should do the belt too,if you get your belt from Auto zone or NAPA the belt routing is on the back of the package

The diagram should be in the engine bay somewhere. usually on the front crossmemeber or possibly hood. If that doesnt work, contact one of your local autoparts stores. They should have a database that they can print a diagram from.

The belt tension is automatically adjusted with the tennsioner pulley. As far as putting it back on, I am not sure what you mean, you just need to bolt it back up and pull the belt over the pulley.

sounds like belt is loose and when load is put on it it just slips and wont engage the compressor and it will squeak. try tightening the belt or check to make sure your tensioner isnt bad

ONE OF THE PULLEYS SHOULD HAVE A SQUARE DRIVE (3/8 DRIVE) PUT A RATCHET IN THAT HOLE AND ROTATE THE "TENSIONER" TO RELEASE TENSION ON THE BELT.

i looked it up ,,,it seems to me it is the supercharger pulley...if you do not have the supercharged model it is most likely the alternator.