470 mercruiser alternator belt being trashed?

[Bewildered4toolong]

I have a 1978 Fiberform Cougar , a 470 mercruiser in it, The alternator belt is really trouble. The belt slips, smokes, Iv seen the alternator pulley get soooo hot it actually has melted a belt in two pieces at the Alt Pully. I have replaced the alt, used new belts, cleaned the wire connections and even installed a larger ground, to no avail... =( Just how tight should this belt be? This is also a replacement kit for the original Merc alt, and everything is installed correctly and the pulleys are aligned with one another. The Engine temp is running in its operating range, and the boat really runs extremely well except for this one problem. The belt and pully get hot, smoke and the belt fails, it really is driving me BatGuano!!! Any Suggestions?

 

[bigbrownbuku]

Re: 470 mercruiser alternator belt being trashed?

could be a large current draw. perhaps increasing the reserve capacity of your battery/s would help. what size wire is connecting the alternator to the starter batt+

 

[Haut Medoc]

Re: 470 mercruiser alternator belt being trashed?

I think that if you press on the belt with moderate pressure between the pulleys a 1/2" deflection should ok.....J

 

[Bewildered4toolong]

Re: 470 mercruiser alternator belt being trashed?

I thought about that, too much current draw, Although I have yet to find a direct short to anything and the only draw I use when running is the blower and the radio at times. <br /><br />I also have checked the belt after installation and periodically, I have between 1/4-1/2 inch of deflection, although I think 1/2 inch may be too much, with 1/4 being more within tolerance and a tighter adjustment without being too tight.

 

[TGG63]

Re: 470 mercruiser alternator belt being trashed?

I have the same problem on a 1983 Merc140Hp. Belt either is eaten up or keeps popping off. I shimmed up the alternator pulley as much as I could for the pulley to be in alignment. It's still about 1/8" off paralell alignment and the belt still pops off, or gets eaten if I make it really tight. I have the same theory that there is a large load on the alternator, effectively seizing it (it turns freely when disconnected). What would be causing the huge load (draw)? Could a dead battery do it? I can start the engine and run for about 15 minutes before the belt pops off.