Alternator issue 4.3 Mercruizer

[garthwjensen]

I recently took my boat out after the winter and it worked great the first trip out even though it seemed as if the alternator was not working properly. I was reading 12 Volts or so when going slow speed and it would drop below 12 V when going faster 3000 rpm or so. I was going on a longer outing in a couple of weeks so I though I would purchase a solar battery tender. The tender I purchased puts out 20 Volts or so in full sunlight and instructions say you can connect directly to battery with alligator clips supplied. The first day of trip was ok but with same issue as above. So I connected the solar charger as directed and we went out on boat following afternoon disconnecting charger before starting engine. The next day out we were going along ok then we heard a high pitched squeal and smelled burning rubber I immediately assumed something up with ceasing alternator. Could the extra voltage put in by tender created an issue even though I disconnected at startup? Or did latenator just fail because belt to tight or something? Any way I know I need to order a new alternator. The motor is is a 4.3 Liter V 6 serial number OD817803 and I currently have the now defectiveSAE J1171 alternator. I want to know if this is the correct alternator for my motor. Also if the battery was connected backwards at one point could that have messed thing s up initially. A boat repair shop seemed to connect battery backwards. Also is mercruizeer negatively ground to minus side on battery?

 

[nola mike]

It doesn't sound like your alternator was working correctly at all this year. It should be putting out closer to 14 volts. If anything, you need to be worried about the battery with the tender attached, although I doubt the amps are high enough to do any damage. Yes, battery connected backwards can fry the alternator, although in later engines there's a fuse to prevent that. Also, it wouldn't cause the bearings to seize. The SAE J1171 just means that it's a Marine alternator. There are many that will fit your engine, I've had good luck with DB electrical. Lastly, your engine does have standard negative grounding. Oh, don't forget to get a new belt as well.

 

[garthwjensen]

It doesn't sound like your alternator was working correctly at all this year. It should be putting out closer to 14 volts. If anything, you need to be worried about the battery with the tender attached, although I doubt the amps are high enough to do any damage. Yes, battery connected backwards can fry the alternator, although in later engines there's a fuse to prevent that. Also, it wouldn't cause the bearings to seize. The SAE J1171 just means that it's a Marine alternator. There are many that will fit your engine, I've had good luck with DB electrical. Lastly, your engine does have standard negative grounding. Oh, don't forget to get a new belt as well.

Thank for your quick response I was planning on getting new belts I have ordered from DB electric before and had problems with alternator it worked for a day or two then same issue I want to make sure I get the right alternator could you recommend the correct good one from DB electric.