I have been into Boating and Automotive repair/restoration 45 years. Seems like occasionally I come across a situation that I can't figure out and this is one of those.

mt port engine on my 255 Formula has developed an alternator belt squeal thats driving me nuts. The first belt started doing it and seemed a bit loose so I tightened it up and it quit squealing...but within an hour of running it shredded to pieces. I chalked that one up to it being a NAPA Automotive belt. I replaced it with the Gates "Green Stripe" version of the Mercruiser P/N that is 45" long. As soon as I put it on it started squealing...it too seemed a bit loose so I tightened it up with no change.At this point I picked up a can of Belt dressing and followed the instructions. The belt was quiet immediately and I thought I had solved my problem...but 24 hours later...I started the boat and the same belt was again sqealing!!

So I don't know what... but something is out of whack...new engine, new pulleys, new alternator, new belt.

Any ideas?

Take that belt off and clean off all the pulleys with brake clean. Put a new belt on and spray it with hairspray. It's an old trick for supercharged stuff to get more grip.

check how the belt rides on each pulley.

Even though new alternator could be bad. Seen it many times. Just a thought.

you have the wrong style v-belt,,it you have a ,,oh never mind ill only get sarcasm on here....ill call you....im done with helping people on here..

Thanks for the tip Mike...I appreciate it.

Nah FIXX don't stop - you saved my ass many a time and it is always much appreciated!