occasional squeak with slight pressure on the throttle - didn't sound like the belt, but I replaced it anyway. Squeak remained. Over the past few weeks, squeak got more regular still only with throttle pressure. the squeak disappears when I coast. Based on the location of the sound, I believe its the water pump or the alternator. i can't get either to make noise with the belt off. I suspect water pump. Is there any other way to tell what it is? I don't want to wait for a failure cause it will be someplace like an underground parking lot. Any advice is appreciated.

i replaced the belt tensioner shock, spring and idler pulley within 25,000 miles.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900