Bad alternators on bf150bs

"Have now replaced both altern

"Have now replaced both alternators on my two bf 150's. Hours are about 220 on each, they are '04's. First one replaced under extended warranty and the second went out about 5 to 10 hours later. Although under warranty I paid for it so as to keep the alternator for inspection.

Local alternator shop found the brushes completely deteriorated with the metal component caked around the shaft such that the shaft had been grooved under each brush.

They also found a greasy, filmy substance all over the inside of the alternator and speculated that this substance caused the brushes to break down.

Motors have been dealer serviced annually and were bought new. Dealer has contacted the Honda rep who says not their problem. Dealer also contacted Corrosion X - the rust inhibitor they use under the cowling- who says their product won't cause that.

Have called Honda's Retail customer service line who was not interested in problem because the engines were no longer under factory warranty, although were covered by extended warranty.

Primary concern is to find the cause to prevent further failures. Anyone have any suggestions?

Thanks in advance.

John"

"[They also found a greasy, fi

"[They also found a greasy, filmy substance all over the inside of the alternator and speculated that this substance caused the brushes to break down.]
I agree, so it looks like Corrosion X has caused the greasy, filmy substance, & failure. Alternator brushes need to be kept dry."

"Thanks, Bob. I didn't kn

"Thanks, Bob. I didn't know if some other condition such as excessive heat might cause it, or if there was simply a "bad batch" of those Denso alternators.

John"

"Minor amounts of oil will als

"Minor amounts of oil will also cause that problem. I would do a real thorough inspection of the outside of the motors and the inside of the cowlings to look for traces of oil. It may be possible that there are bad seals or clogged/restricted breathers that are throwing small amounts of oil into the space under the cowling, which would subsequently settle on the alternator."