Alternator pulley overheats and melts belt

[jamspears]

I have a 97 nautique with PCM 40 351 Ford. The alternator started melting belts. I went thru a couple belts in just a few minutes. The pulley gets red hot. I replaced the alternator with a brand new Mando 55amp just like the old one. Exact same behavior. Just idling for a minute gets the pulley overheated. The alternator itself is not hot, just the pulley.

Now I'm assuming some other kind of electrical problem. I can't find any useful help online for this particular problem considering I have a new alternator and new OEM belts. Ideas I could try to resolve this? Thanks.

[Neverenough]

I dont know much about fords but is the voltage regulator built in to the alternator? Also if you have that big of a short I'd check every cable in that boat. Grounds and power. Lucky it has not caught on fire.

[jamspears]

The voltage regulator is built into the alternator. Checked power and ground

I dont know much about fords but is the voltage regulator built in to the alternator? Also if you have that big of a short I'd check every cable in that boat. Grounds and power. Lucky it has not caught on fire.

The voltage regulator is built in to the alternator. Power and ground seem to have solid connections. There must be something else I can try. I'm running out of ideas. Thanks

[sodbuster88]

Have you checked your pulley alignment to belt travel (is your alternator lined up ok)?

[jamspears]

Bad battery

Have you checked your pulley alignment to belt travel (is your alternator lined up ok)?

Checking pulley alignment, etc was one of the first things I did.

Bad battery seemed to be causing the problem. Even thought the boat started OK with the battery (and it tested OK at the auto parts store), there obviously were bad cells in the battery that made the alternator think it had to push a lot of power to the battery or something like that. After replacing the battery, everything is now running normal temperature and belt is no longer smoking/melting. Thanks.