landover50
Seaman Apprentice
- Joined
- Jul 29, 2016
- Messages
- 33
I've got a Mercruiser 5.7/V8 Alpha One Thunderbolt engine, serial number 0C764258 with a Mando #AR-150 alternator. The boat is over 30 years old and I'm guessing this is the original alternator.
I was on a fishing trip this last weekend and had charged the battery prior to leaving. I was running the engine intermittently to ensure I was charging the battery but it died (while night fishing with 3 kids, turned out to be an interesting nigh
) I was running some LED lights and a fish finder but not for that long. It got me wondering if my alternator was doing it's job. I tested the voltage at the battery while running and was only getting 12v. So I revved the engine and still only got 12v. While revving the engine I was inspecting the alternator and the noticed one of the washers on the positive terminal turning/glowing red in a spot. There are a number of washers and nuts on that post and they were all pretty loose, not tightened down. So I decided to to pull them off and give them a good clean before re-tightening. The first nut was rusted pretty good and when I turned it, it twisted the end of the bolt/post right off. But there was one other nut so figured I could use it to tighten everything down. I pulled all the washers/nut and cleaned them. I also cleaned off the connection from the condenser as well as the orange wire connection. But when I put it all back together it instantly started to turn red and started a mini fire, melting the connection from the condenser and welding the first washer to the alternator. You can see in the pic that the round connector from the condenser is melted half off. My question is, what did I do wrong? All the wires were connected to that post previously, doesn't seem like I put a wire where it shouldn't be. Did I do something wrong or could it be a problem internal to the alternator? I plan on getting it rebuilt or buying a new one and want to make sure I don't do anything wrong when putting it back together.
Also, while doing a quick inspection of the wiring harness I noticed a black wire coming from the main bundle out toward the breaker/starter slave solenoid that isn't connected to anything. Without tearing apart the main bundle I don't know where this is coming from/going and don't know where it should be connected. Being a black wire it seems like it would just be a ground but not sure where it should be attached to, shown in picture attached. Any help on these two issues would be appreciated. Thanks.
I was on a fishing trip this last weekend and had charged the battery prior to leaving. I was running the engine intermittently to ensure I was charging the battery but it died (while night fishing with 3 kids, turned out to be an interesting nigh
) I was running some LED lights and a fish finder but not for that long. It got me wondering if my alternator was doing it's job. I tested the voltage at the battery while running and was only getting 12v. So I revved the engine and still only got 12v. While revving the engine I was inspecting the alternator and the noticed one of the washers on the positive terminal turning/glowing red in a spot. There are a number of washers and nuts on that post and they were all pretty loose, not tightened down. So I decided to to pull them off and give them a good clean before re-tightening. The first nut was rusted pretty good and when I turned it, it twisted the end of the bolt/post right off. But there was one other nut so figured I could use it to tighten everything down. I pulled all the washers/nut and cleaned them. I also cleaned off the connection from the condenser as well as the orange wire connection. But when I put it all back together it instantly started to turn red and started a mini fire, melting the connection from the condenser and welding the first washer to the alternator. You can see in the pic that the round connector from the condenser is melted half off. My question is, what did I do wrong? All the wires were connected to that post previously, doesn't seem like I put a wire where it shouldn't be. Did I do something wrong or could it be a problem internal to the alternator? I plan on getting it rebuilt or buying a new one and want to make sure I don't do anything wrong when putting it back together. Also, while doing a quick inspection of the wiring harness I noticed a black wire coming from the main bundle out toward the breaker/starter slave solenoid that isn't connected to anything. Without tearing apart the main bundle I don't know where this is coming from/going and don't know where it should be connected. Being a black wire it seems like it would just be a ground but not sure where it should be attached to, shown in picture attached. Any help on these two issues would be appreciated. Thanks.
