Belt runout

My brother and i had replaced the idler pulley and the tensioner pulley oh his 1999 taurus wagon with a 3.0l and after we changed them we put a new belt on it and after about 10 mins of running it started to runoff the alternator pulley put the old pulleys back on and it runs fine except a noisy squeal so we put the new ones back on again and same problem except after about 35 mins it ran off again is there something we are missing this is getting expensive replacing serpentine belts. Like i said with the old pulleys it runs fine just very noisy new ones runs quiet just blows out serp. belts :banghead::banghead::banghead::banghead::banghead: :banghead:

It sounds like you have enough justification to return the new pulleys as defective. Try getting a different brand. Make sure you're are purchasing pulleys for the correct engine and accessory list. Do the new pulleys look any different from the old ones when laid side by side?

-Rod

Hi, Sorry i didn't get back sooner as i have been busy. The pulleys looked pretty much the same side by side and after replacing them both again and another serpentine belt we figured some else must be going on so after he talked to a millwright at his work they told him to try wirebrushing the pullies and try again because when the belt ran off it might have left debris in the grooves of the pulley so after he did that he put the new septentine belt back on as we managed to save it before total destruction and low and behold it ran fine for 25mins last weekend and for another 25-30 mins this weekend so it was just probably some debris we couldn't see that was making the belt track towards runoff but thanks for the help but it seems to be fine for the moment.

PS. every serpentine belt should state wire brush the pulleys before installing a new belt so far this has cost him 120 in belts and 80 in pulleys:banghead::banghead::banghead::banghead:

Thanks for the follow-up. I have read of other folks wire-brushing the pulleys, but I think that was typically to fix a chirping noise with a new belt. This is another trick to add to the, well, book of tricks.

-Rod

Are you sure one of the other accessories doesn't have a bad bearing in it?

I'm just thinking of something that happened to me once with an '88 ford pickup. The serpentine belt kept jumping just one groove off. I finally noticed that the water pump bearing was extremely loose, although the water pump didn't leak. I don't know why it took me so long to notice that. I just thought I would mention something like this as a possibility.

Are you sure one of the other accessories doesn't have a bad bearing in it?

I'm just thinking of something that happened to me once with an '88 ford pickup. The serpentine belt kept jumping just one groove off. I finally noticed that the water pump bearing was extremely loose, although the water pump didn't leak. I don't know why it took me so long to notice that. I just thought I would mention something like this as a possibility.

Yeah we thought of that he is ordering a new p/s pump,water pump and already has a new alternator so the only thing that will be left is the A/C compressor, and crankshaft pulley, he really wants to have it fixed before the weather changes so i guess i will be busy the next couple weekends as i have some repairs to do to my own vehicle this weekend (Brakes, Exhaust,and a couple other small things)