The serpintine belt slipped off, the tensioner broke,the truck drove on for awhile then stalled didn't over heat just killed the battery. later when I tried to start it, the motor was hard to start & it was making some pretty loud banging sounds.Q:did I kill the timing chain? Q:my truck is a 96/350vortec/2500,does it have a belt or a chains?

CK SERPINTINE BELT TENSIONER ,IF IT IS NOT MANTAINING CORRECT TENSION ON BELT IT WILL SLIP AT HIGHER RPM, ALSO CK BATTERY ,BAD CELL CAN CAUSE THIS ISSUSE

Well firstly if your wife drove the car for 5 miles with the tensioner broken, then the belt being lose will have slipped a couple of teeth. Did you set the camshaft and crank alignment marks correctly before you fitted the new tensioner? If you did and it still won't start then that means that you have one or two bent valve's in the cylinder head.You will have to remove the cylinder head and replace those valves or that car will never start again.

check condition of belt. If a "v" belt the back of the belt must be level with the top of the pulley otherwise the belt slips under load and it take power to drive an alternator while charging check belt tension and adjust if necessary. If a serpintine belt-multigroove make sure the belt is properly tensioned

Check your belts make sure they are all there.

this has a serpintine 1 peice belt that has a single belt tensioner with a square drive in it you simply push tensioner against spring pressur and carfully hold and slip belt off 1 pulley then slowly let tensioner back to its stop,there should be a belt routong diagram on fan shroud or simply draw a picture of pulleys and belt routing before removal,then reverse procedure quite simple acully

Typically a belt will come off if all the pulleys are not perfectly aligned.
If you recently replaced a power steering pump and the pulley was not properly seated all the way down where the pulley front is flush with the metal shaft from the pump then you will shred the belts and they will come off. If you ONLY swapped the tensioner and idler pulley you may have installed the tensioner so it isn't parallel to the other pulleys but that would be very rare because it would have been difficult to get the belt on if it was not properly installed. There also could be a damaged plastic pulley that could be "cutting" into the belt which would also cause the belt to slip off.

First draw a diagram of the belt routing. Next have a 3/8" ratchet in hand. The ratchet will be used to insert into the belt tensioner 3/8 slot to releive the tension to the belt. Upon releiving the tension you can slip the belt off which is the easy part. Now reverse these directions to install the new belt and be careful not you pinch your fingers

If the belt keeps slipping off the you need to replace the tensioner(its the pulley you have to move to get the belt on and off,and that part should be inexpensive to replace from any parts store.

If the belt was slipping or became contaminated with oil or coolant that should resolve the problem. Check the belt tension first before replacing the belt

look at the belt tensioner while the car is running and see if it is jumping up and down and if it is replace the tensioner