Bob/Stu/Maine,
This is an older Volvo MD17C that I've rebuilt over the past few months. See "engines/propulsion forum". I agree that it was a bolt failure, but the bolt sure had a strange wear pattern on it and was not tight in the alternator ear sleeve. This has probably been in the making for years and may not have even been the original or correct bolt. I've only had the boat a yr. I probably did not notice it when I reassembled it after putting the engine together. The hole in the alternator ear was slightly ovalized so belt alignment probably was not optimum and the bolt was a higher grade bolt I believe. (three slash marks on the head pointing toward center. I used to know the designations). The whole point of the post was to share my realization that if something happens wrt alternator (such that it doesn't turn for whatever reason), a different size belt could be employed such that the engine can keep running as the FWC pump can be turned with a different sized belt off the flywheel. You don't need an alternator to run. As GeorgiaBill stated, a belt can be bumped on. It might be loose, but it would/could get you somewhere where more effective repairs can be made. In the PNW, there are many very remote places where you could get stuck depending where ya go. Many people have (inexpensive) parts flown in by seaplane at great expense. I don't plan on expensive belt/pulley mods. It would be expensive for this engine as the flywheel/ring gear are involved. I resleeved the alternator ear and I'm putting in a known grade 8 bolt. No bolt wobble in the ear. Took a 1/2 hr to do and I sure did not want to spend a lot on an original 35a alternator. New alternator on the list for probably next yr...and I carry a Honda 2000
