Can anyone help please? The alternator failed on my Merc 5.7 (2003/4). Next morning it was found to be very hot after an overnight stop. Yard replaced it, but after about 4 hours use (2 cruises) it seems to have burnt through the drive belt. Fitted new drive belt, 10 mins running and the new alternator is now very hot. The bearings are turning freely, so I suspect some kind of electrical fault on the boat. Any advice greatly appreciated.