stretched? serpentine belt

Any of you guys have problems with getting the serpentine to stay tight and not stretch so much that it actually hits the p.s. pulley? It also slaps around and makes noise when you put it in gear and don't move, AND have the a/c on at the same time, such as at a stop light.

This is a weird one. Put on a new Gates belt and had about 3/4" clearance between the tightener and the p.s. pulley. After about a week or less, the belt was hitting the p.s. pulley when the a/c was on and you were idling with it in gear. If you put it in neutral OR turn off the a/c, it gives it just a little clearance and quits slapping around and making noise. Also stops hitting the p.s. pulley.

Thought to myself "piece of crap Gates belts", so ordered a Dayco from Checker. Looked and worked great for about a week, then did the same as the Gates.

Put on a new tightener, which didn't help.

Went back to where I got the Gates belt to check it against a new one, and the measuring device shows that they are exactly the same size??????????????????????????????

Now I'm scratching my head, wondering what to try next. All pulleys, idler, etc. seem nice and tight. Only play that I could notice at all, was some end play in the p.s. pulley, but that's normal and shouldn't cause a problem anyway.

Any help and ideas WILL be tried.

Thanks guys,
Lawton_kid

Two things, make absolutely certain that they are giving you the correct belt for your car. I have never heard of a serpentine belt stretching in this manner before. The old v-belts would stretch after many miles and would require retightening but with the tensioner on the car the belt should stay tight. Second, make sure that all accessories are completely tight. You may have a bolt that is loose allowing the ac compressor alternator or ps pump to move. If both of these are correct see if you can find a belt that is slightly shorter than the one you are using this may solve the problem.

I might have been hallucinating, when I thought they stretched that much. The 2 belts that they gave me were a 535 (last three digits of the size number). I put on a 530 from my son's '95 Esky and it looks great so far. Put the 535 on his car and that seems to be ok so far, also. I'll keep you posted.
Kid