'08 F-150 Issue

[jooger17]

I bought this truck new in '08 and have had fantastic luck with it. Outside of routine maintenance, I changed a power steering pump and solenoid. The only issue I have is it has broken the serpentine belt several times. It first started about 110,000 miles. I chalked it up to me not doing it on the 100k mi maintenance. Less than 3,000 miles later it broke again. I took it to the Ford house, they changed the water pump and the belt. That lasted about 5,000 miles and it broke again in Stanton on my way home from work. I dropped it off at another Ford house and told them to replace every pully on the chain. On top of that they had to replace some wiring that was torn loose when the belt broke.

This last time I cranked my truck to let it warm and was strapping my daughter into her car seat when I heard the belt break. I ran around and killed the engine, popped the hood, and sure enough that's what it was. This belt probably has 50-60k miles on it.

I could just put another belt on it, but I want to know what could be causing this? The belt itself isn't worn bad, no dry rotting or anything to indicate it was in bad shape. I'm assuming one of the pullies seized up again. I'm a long ways from a mechanic and I odn't want to just drop it off at the Ford place and tell them to have a field day.

[AJMag]

What does the belt look like at the point where it broke, like clean cut, ragged tear, etc? No signs of overheating or partial melting on either side of it? Normally if something freezes up there would be some sign of over heating or melting. One of my first thoughts would be if the compressor clutch got locked up. Also, if one of the accessory units, like p/s, alt, or w/p is getting stiff, then it'll put extra strain on the belt. Really hard to say without looking at the belt or truck in person.

[100%TtId]

Does it have a tensioner pulley? Maybe a burr or nick on it.

[jooger17]

What does the belt look like at the point where it broke, like clean cut, ragged tear, etc? No signs of overheating or partial melting on either side of it? Normally if something freezes up there would be some sign of over heating or melting. One of my first thoughts would be if the compressor clutch got locked up. Also, if one of the accessory units, like p/s, alt, or w/p is getting stiff, then it'll put extra strain on the belt. Really hard to say without looking at the belt or truck in person.

It's a pretty clean break. No melting or signs of heating.

Does it have a tensioner pulley? Maybe a burr or nick on it.

It does have a tensioner pulley and there wasn't anthing on it that I could see. I had it replaced as well during the last incident.

[Sleepy]

Ill run it by our mechanic Monday. We run all Fords in our fleet and he's pretty much seen it all from F-150's to F-550's. He might have an idea. Always hard to tell without being there, but I'll relay all the info you've provided.

[super_dave]

Man that's crazy! I have the same truck with 150k and the original belt.

[BigThicketBoy]

Steve seems the most common cause is bad after market parts , pulleys and shafts not aligned right . Maybe you got a bad power steering pump? Check on some of the Ford forums.

[WCB]

Pulley/shaft alignment was my first thought also. My 04 F-150 5.4L has 200K+ and I changed the belt once for the heck of it.

[BloodSpiller]

If there are no misalignments of the pulleys then I would probably just blame the belt itself and replace it with a green Gates belt and see if it happens again. A seizing pulley, a burr or a misalignment causing the belt to wear on one side are the only causes that can break the belt. I believe the last one may have just been bad luck.