HellOrHighWater

'96 f-150 302w

I hate to post but I'm at a loss here! I noticed that my serpentine belt kept wearing in the same place, the last groove closest to the head; so I did a little investigating. I realized that my tension pulley was out of alignment to the rest of my pulley's. I replaced the whole tension assembly/ pulley. When the truck is cold it makes an awful knocking sound, and I discovered that the tensioner is being pulled up and down slightly making it knock against the stop for the spring and vibrating. It's a very loud knock that eventually goes away when the engine is warm. I have the AC delete idler installed, has anyone ever seen or dealt with this?

terry274

It sounds to me as if you have another accessory with a bad bearing. It is probably seizing, then releasing. Check the power steering pump and alternator as well as the water pump.

Phil48315

I would guess as the engine warms up the belt grows a little
Heat = expansion
If the tensioner is knocking against the stop I would try a slightly longer belt.

David Young

My belt kept wearing like yours. Ended up being the water pump bearing was worn out. Replaced the water pump and all is good

HellOrHighWater

Thanks for the advice guys! I am going to do a little more digging today and see what I come up with!

HellOrHighWater

As it would turn out, the crankshaft has about 1/4 of play. I figured the thrust plate and front bearing are worn out.