Alternator Noise??

[agutowski3388]

i have a 3.0 1987 Mercruiser 130 hp # 0B698590

I am getting a sound from the alternator. it sounds like a rattle and it does go with the speed of the engine (more rpm fast souning rattle). the rattle goes away the more speed of the engine and at crusing speed there is no rattle at all (not just cause everything is so loud i cant hear rattle its just not there at all) only hear the rattle (quite loud) in no wake zones and louder sometimes then others for no reason. Pulled off the cover and it was coming from the alternator.

Im just about positive its coming for the alternator only thing is im getting charge from it and my batter is always around 12 volts.

so what the hay?? do i have a bad alternator or what??

 

[chiefalen]

Re: Alternator Noise??

What charge that alternator putting out, check it with a external meter. Could be the bearings going, alot of people over tighten the belt.

 

[TommyA]

Re: Alternator Noise??

Unless you have a serpentine belt for all pulleys you could disconnect the belt that is on the alternator and start the engine up to make sure it is the problem. With the belt off you would be able to wiggle the pulley to see if there is any play in the alternator shaft. Sounds like a bearing is going bad.

 

[agutowski3388]

Re: Alternator Noise??

not sure, it must be pushing well enough, starting out the Voltmeter on the boat will say bettween 10-12 volts then when i go crusing for a while its at 12-14 Volts.

cant check it for another 3 weeks