'94 LeSabre Serp. Belt MYSTERY

[TTCzar]

So far no one can solve this mystery.

'94 LeSabre: just installed new water pump myself, dealer installed new A/C delco reman Alternator in 3/03. (yes a little backward but I didn't know about this forum back then, and I feared the serp. belt tensioner like a rattle snake waiting to bite me ))

My water pump was replaced becuase the flange which pulley mounts to broke off while I was driving home from work...thank God very closed to home at the time of the break. I was lucky to find the pulley in the engine compartment, undamaged, w/ the broken flange attached. Broke off right at the end of the w/p shaft.

Now, here's the belt mystery. All part catologs, and the A/C Delco parts site call for a 1025K6 belt. I was so proud of my water pump job, I splurged an extra 3 bucks for one of those "gator belts." Said right on the package, "the quite belt." That was a joke, although now, I think maybe it wasn't their fault. My power steering pump was screeming like a siren w/ this belt. I sized it up to a Kelly 1025k6 and it seems about 1/2 inch longer. I didn't realize this at the time, but the tensioner was probably bottoming out and the belt was slipping on the P/S pump, hence the noise. Exchanged that belt for a Kelly 1025k6. Nice and quite--problem solved? Not quite. The stop on the tensioner was less than 1/4 from bottoming out. That meant to me, any strech in the belt, or expansion in hot summer temps would cause the tensioner to bottom out and belt would become loose. That w/p pulley and the belt travel in general, runs so close to the motor mounts I don't want to chance that belt falling off, or become loose enough to contact the mounts and break the belt and maybe the w/p again becuase chuncks of belt wedge between the w/p pulley and the engine mount.

Does anyone know why a NEW properly sized belt (1025k6) would only take the tensioner up from the bottom by 3/16 inch? The Alt pulley size is correct, the w/p pulley was reused from previous, and sits at the same height as w/ old pump. Nothing else has changed (to my knowledge) on the belt path, yet it seems this size belt is a little too big.

Today, I put in the next smaller size belt, or 1020k6 and the tensioner is riding higher from the bottom stop, at least enough to increase my comfort level. However, I wonder, has anyone else seen anything like this? I have one more 1025k6 I'm going to put on the wife's '90 LeSabre, I'll see how that works out tonight.

Thanks for reading.