Hot alternator HELP (I(39)m new here, not sure if I(39)m doing this right)-gctid816394

[Kresendis86]

Hello everyone! I'm new here, just joined tonight. I'm not even sure if I'm posting this in the right spot lol. Forgive me if not!

We bought our first boat a couple days ago because it seemed like a good deal for a starter boat. It's a 1995 Bayliner with a 3.0 mercruiser.

We've ran into a few issues since buying it, which we thought would happen and don't mind putting a lil money into it. We're a little confused at the moment though because the alternator is getting extremely hot to the touch. Here's a breakdown of what we've been through so far.

First the boat wasn't getting any power when we bought it. We bought a battery and a guy helping us out bypassed the circuit. Then everything was working but it wouldn't start or turn over. So we bought a starter (4 stud) and replaced it (old one was 3 stud). We also replaced the circuit.

It started right up and sounds great. We took it to the lake to give it a try and the alternator was running super hot to the touch. We decided to go home and mess with it some more. Here at home they unplugged the positive battery cable and it doesn't run hot. But if it's plugged in, alternator is extremely hot.

Any ideas? Suggestions? We're very new to the boat world and don't know much about them.

Any help would be greatly appreciated! Thank you.

[Pcpete]

First, Welcome! Just from my experience and I'm no expert, I'd pull the alternator and have it bench tested at the local parts store. If it indeed shows bad, DO NOT buy an automotive atlternator. Period. Starter either. They look the same but there are anti spark features built into each of them, and the carburetor that try very hard not to have an unintended explosion. If the alternator is bad, do some shopping on the internet and you should be able to find a replacement, delivered to you in a few business days, for $50-60. I use Amazon Prime enough to more than pay for itself. If you have a Mercruser, serial numbers are really important. Changes are made at a serial number point rather than model year for them. There are several online companies that have the microfilm drawings with the correct part number for your engine. The parts books are also available for OMC an Volvo from many of the same parts houses.

You should also look for a hard ground that shouldn't be there. AKA a short. It may not be enough to blow a fuse but is certainly eating some power. I would start with a careful visual, like painstaking careful, examination of the positive wire coming off the alternator. Look for a place where the previous owner spliced or added a wire. I've seen negative wires spliced into a hot lead with interesting results. Not always a hard ground, but a power eater. Stereos and amps are classics for that one.

Let us know how it goes.

[Kresendis86]

Thank you! I'm definitely going to share your response with my husband. Hopefully we can figure this out! I've been buying parts at the marina vs auto store. More expensive but I figure it's probably worth it to get the right thing lol.

[Pcpete]

There are lots of parts that are used both places that are not an issue, however, some have subtle differences that make a huge difference in the marine environment. Please add a signature that tells us a bit about where you live and your boat. You just might be neighbors with a member here who can come over and help.

[carguy]

When you say, 'we bought a new battery and the guy helped us bypass the circuit" what exactly does that mean?

[captharv]

Bypassing the alternator regulator will do two things, and do it very well:

1. Guaranteed to fry the battery.

2. Guaranteed to fry the alternator itself up to including catching fire.

Take the alternator to an automotive alternator and starter shop. They can test and repair it.

DO NOT put an automotive alternator or starter in a boat. The marine one is spark protected so you don't get a loud bang out of your boat.

[Kresendis86]

Thank you! Great idea I will do that!

[Kresendis86]

When we first got the boat we bought a new battery. The lights and dash gauges wouldn't work even with new battery. A guy that works on boats locally came over and said it needed a new circuit because once he bypassed it, everything worked.

[builderdude]

Think he/you meant bypassed the circuit breaker.

[Ruffryder]

Gauges not working...ignition circuit dead most likely.

Yup bypassed the breaker or fuse possibly.

[Kresendis86]

Sorry! Yes, it was the circuit breaker.

We took the alternator out and to be tested but the local auto shop couldn't because it wasn't a plug in one. The marina said they could test it if it's in the boat. We came home, cleaned and rechecked the wires and put the alternator back in. Started it up and let it run for a while and it's no longer heating up. We might go try it in the lake this afternoon.

Thank you everyone for the input!