1994 4.9l w/ac
So we got a lot of rain this past week and I hit a big puddle splashing way too much water into the engine compartment. As soon as I hit it the serpentine belt came off. I didn't have the tools with me so I drove the truck home the two miles without the belt. upon arriving home, with no p/s and a very hot engine I put the belt back on several times. It kept slipping off and going behind the idler pulley. I finally got it to stay on but it was chirping because it had been damaged when it originally slipped. So today I bought a new belt and put it on. This one stays on with no issue, but it clicks when running. One rib gets pushed off the back of the P/S pulley and then the belt is forced back into place and so on. My P/S pulley has a back/forth play of about 1/8 inch or less, I was told this wasn't a huge issue. Is that wrong? Why won't this new belt just stay in place?

The idler pulley is new, the tensioner has been replaced and is still within the wear range, and the P/S pump was replaced in 2009.

 

Idler pulley? The 4.9 doesn't have an idler pulley, you must mean the tensioner pulley. Mine does this too but I haven't looked into it yet.

 

Yeah that's what I mean. Would the play in the pulley be a factor in the jumping?

 

No, I don't think so. Most have some play. I'm thinking mine is the tensioner but I haven't tried anything yet until my half a belt snaps.

 

Okay. I'm hesitant to put the new belt on there. I don't want to willingly chew up a new belt.

 

Check for loose, missing, or broken bolts that hold the bracket assembly(s) to the engine block.

 

From what I can tell nothing is loose, broken, or missing. I'm stumped. I've put the new belt on several times now and it always jumps the P/S pulley. I haven't tried putting the old belt on, that'll be tomorrow. This is a stupid question, but I've never really done much with belts. Is there a specific side that has to be on the engine block side? I'm almost positive there is no "special" side, but just checking. I can't think of any other reason. I'm stumped.

 

No special side, but mechanics usually put it on so the belt markings can be read standing in front of the truck. So it rotates the same direction when reinstalled.

 

If the brackets which hold the ac, air pump, alternator, etc are all well secured i would be inclined to think that something that's driven by the belt is about to fail.

ie: Let's say that the water pump was on it's way out. It might turn freely for awhile and then the bearings "catch" causing the belt to jump off the pully.

Could be the tensioner ? If that's not working back & forth freely ? If the action is stiff ?

When you look at the pullies, are they all lined up with one another ? If one thing is sticking out a bit further than the rest or cocked sideways that could cause the belt to ride over too.

Have you double checked the belt routing to see that the flat side is engaging the flat pullies and the grooved side is engaging the grooved pullies ?

Just some possibilities that come to mind ....

 

replace the tensioner... as it wears it ***** and it leads to throwing the belt.

Another issue is it does get dust/dirt in it and that restricts the travel.... it cannot bounce back as fast as it should so when it needs to tighten it cant fast enough so the belt flies off...