Alternator making screeching noise

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Alternator making screeching noise

I have a 8MR2050FA alternator on each of my Volvo TAMD41B marine diesel engines. One of them has started making loud screeching noises the last two trips out. I thought I fixed it by tightening the mounting bolts. No luck. The belts are tightened correctly. They are not slipping.

Now, I´m beginning to think a bearing might be going out. Could this be a correct assumption?

Anyway to confirm my suspicions other than pulling it and taking it to a shop? It appears to be charging. It does charge the house bank so it might be working much harder than the other one.



Mark Timerman
Prestolite Electric
Texas, USA
Posts - 580

  Good day Bill. Almost always screeching involves loose belts, can you turn the altenator pulley by hand when the engine is off?? Is the alternator possibly putting out its maximum? but you might not be able to tell unless you have an amp meter. What happens when the alternator is disconnected? does the noise go away? What happens if you put just a small dab of grease on the belt?? That should make the noise go away too. Usually bearing noise comes as a rumbling sound. Might be best to call me if you have more questions, my phone is 512-673-3880, thanks

Mark Timerman
Tech service line: 866-288-9853

Bill Waters
Not registered


Sorry for the late response. I've been fishing the past two weekends. The screeching noise is not the typical noise an alternator makes when the belts slips.

I'll try your tips when I go to the boat this weekend and give you an update.


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