Altenator sparking and smoking

I have a 2001 4.3 mercruiser. I took it out to the lake today and upon getting on step there was squeeling comming from the belt or pully system. It was only the second time that I took it out this year to run so I figured it would run a little rusty. The noise subsided once on step, and I cruised at 3/4 speed for about 20 minutes. I came to a stop and opened the deck to check on the engine to make sure everything was ok, I noticed the pully on the altenator was rusty and could be the sourse of the noise I was hearing. So I decided to head back in, didnt want to cause damage or break a belt. When I went to get back on step the noise started but this time louder and it did not quit once on step. It lasted for about a minute and stopped, shortly afterward I noticed a burnt smell(figured it was the belt smoking due to increased tension due to bad pully). I stopped boat but kept engine running, while I inspected it. The altenator was sparking and smoking. So I got towed in, didnt want to risk and explosion with gas fumes. Any ideas why the altenator is sparking and smoking, obviously the pully is bad, buy never heard of an alernator doing that. Thanks

Re: Altenator sparking and smoking

never heard of an alernator doing that

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I have!

Either replace it, or take it to your local alt/starter repair shop.

Re: Altenator sparking and smoking

There are a couple of reasons that this could happen. It is either shorted out and sparking electrically, usually from brushes being gone, or a bearing is seized and the shaft is eating itself. Easy fix, just replace or rebuild.

Re: Altenator sparking and smoking

Sounds like the bearings in the alternator have seized. Or the alternator is 'poling'. Either way, as Don said, replace or repair.

Chris.......
(P.S. what is 'on step'? Never heard that before)

Re: Altenator sparking and smoking

(P.S. what is 'on step'? Never heard that before)

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Another way of saying "on plane"

Common saying up here.

Re: Altenator sparking and smoking

Don S said:

Another way of saying "on plane"

Common saying up here.

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Cheers, thanks... (wierd)

Chris.....

Re: Altenator sparking and smoking

I have just recently discovered this site and wanted to complement the threads and responses from the members. Very informative, wish I knew about this a coulple of years ago while I was having trouble with an old outboard motor. Look forward to reading on.