KRB

I put a new belt on maybe 10-15K ago. Maybe more.

Getting ready for a 500 mile round trip I was checking things out under the hood and noticed the belt was riding one rib over (in) on the AC compressor. Not sure how long it had been like this (day, months?).

So I set it back where its supposed to ride. As soon as its started it jumps back again. Did that several times. The tensionor seems tight. I can just barely detect the most slightest bit of play in the compressor pully, hardly noticable at all.

Whats making it do this? If it likes it there can it stay there? Its not frayed or worn or anything.

Lastly, is it safe you reckon to start the out of state journey?

woodrat

sounds like the tensioner is wearing out and the pulley is starting to ride at an angle, pushing the belt over. The pulley bearing itself could be fine, but the bracket itself is what is wearing out.

I put up with a milder version of your problem for many miles and two belts before I finally changed the whole tensioner and the problem went away.

searcher

No way of knowing how long something will last. I would put the old belt back on for a few miles (assuming very few people throw away the used spare) and see if it does the same thing. I put on an auto zone belt and a few weeks later had a chirp at low speed. Looked for a month trying to locate the offending pulley. For some reason put the old belt back on, chirp gone.

I replaced the PS pump on my F150. The belt did the same as yours. I tried everything to align including changing the pump again. I finally gave up and drove the truck that way another 5 years.

TexasHardcore

The tensioner pulley was plastic on my old '92 D-250. It threw the belts and chewed em up too often. After eating up the Crankshaft sensor wiring and bringing a whole new world of headaches, I bought a replacement pulley from the parts store, then took it to my machinist friend and widdled one out of billet stock aluminum with a lip on both sides to keep the belt from moving. Then I returned the plastic pulley and got my money back. I was contemplating making more of those and selling them, but at the time (a few years ago) there wasn't much interest from others, so I scrapped the idea.

KRB

Yep, I kept my old for a spare. It was fine just starting to show some age. The new one is NAPA.

My idler is metal. So they wear out on the pivit point not the pully bearing? What do new ones run? Metal, not plastic .

KRB

Thanks guys for your input.

Did some more searching and found the threads on pulley costs and replacement.

Think I'll get a non-AC belt as a back up.

KRB

Well I messed with it some more this morning. Or more accurately, it messed with me.

Took belt off, the tensioner is tight, no observable play.
Put belt back on and oriented it on the tensioner a wee bit to the front to make sure that wasn't scooching the belt over one rib on the AC compressor.

Started it up and its immediately back one rib over to the rear.

While running, the only movement is a slight back and forth rowing motion of the tensioner, inline with the belt.

Thats where it wants to be - thats where it'll ride.

Hayseed

I had to change the compressor on the 97 last week and the Napa rebuilt compressor did the same thing on my truck. Check to see if the compressor has loosened up, not likely because they are super tight from the factory, but if it has been changed at all check it. Also make sure the rowing action isn't from some foreign object stuck in one of the grooves on the compressor pulley making the tensioner move. Look at the pulley closely and run a small screwdriver around each of the grooves. I ended up getting another compressor from Napa and mine is fine now.

gcliburn

My belt was doing a similar thing. I fought with it and finally gave up and changed the tensioner. On the truck it looked fine and the pully and bearing were good, but the spring in the tensioner wearing had allowed it to move slightly and wasn't evident until I had it off the truck. My guess is that this may be what is wrong with yours. Hope this helps.

farmer0_1

last fall when i did a bunch of work on my brothers second gen ctd his belt was doing the one off jump. ended up pulley on ac pump was funkey and the water pump was leaking so off it came. after all the changes belt ran true.

wannadiesel

KRB - The tensioner is worn out, replace it. The spring makes the pivot point wear cockeyed, which causes the pulley to pull the belt out of line.

angelfire7

Yeah! KRB, What Wannadiesel said I had the same exact problem as you describe. A new tensioner from Dodge fixed it. NAPA sells one that is made in China. You might want to think about paying the extra money for a Dodge/Cummins.

Joseph

dpuckett

I had the same problem recently, and solved it with a new tensioner.

DP