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Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
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My son has a 93 Four Winns boat with a 5.8EFI Cobra engine

Customer Question

My son has a 93 Four Winns boat with a 5.8EFI Cobra engine and were having Alternator problems. He has owned this boat for 9 yrs and this is the third alternator we've put on it.
What it is doing when we first start the engine, it makes the belt squeal and at this point it is not charging until the belt quits squealing. This is not a bearing or loose belt issue it's like it's trying to reverse polarity or something. The last alternator he had on it worked good for the first two years then it started momentarily making the belt squeal and got progressively worse over the season right up to the point where it would through the belt on start up.
Anyone ever heard of this?
Thanks, Randy
Submitted: 1 year ago.
Category: Boat
Expert:  Joe replied 1 year ago.

Hello Randy,

Thank you for allowing me to assist you, my name is Joe and I will be happy to assist you with your concern today.

You need to check the wiring to the alternator first, next be sure only marine alternators are being used. In some cases alternators when they charge (and going bad) will slow esp under load and with the engine turning faster then the alternator at that point the belt will slip where it can, smoke and or shred. I would need the exact model/serial numbers of the engine so I can see if the regulator is internal or external and for reference of this system in place.

Thank you!
- Joe

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Customer: replied 1 year ago.
Thanks Joe for your response.
Sorry I didn't get back to you sooner but my son was in a accident (same son).
I want to start by saying, I know a little bit,( but not much) about boats. I was in the boat business for sixteen years. This problem that were having has stumped everybody that I ever came into contact with.
In you answer you made reference in a sentence, when alternators are going bad will slow ESP under load. What does that mean? The wiring is good and this is a new Alternator and it is marine it cost him $312.00. The regulator is internal.
Thanks again, Randy
Expert:  Joe replied 1 year ago.

Good morning Randy,

Sorry to hear that and hope he makes a speedy recovery.

What I was referring to/explaining was that if the alternator or when an alternator is not charging/correctly what can take place is a lack of proper voltage, in certain systems this is critical which in this application it is and this can cause the engine to run poorly and or stall.

One thing I would check is that the belt(s) are routed in the correct direction, it's possible that it is ran incorrect and is putting a strain on the system?



Customer: replied 1 year ago.
Thanks again, but this isn't helping. I know your hands is kinda tied without seeing it. Let me give you the long version of the problem. My son bought this boat used. We believe that the seller knew of this problem because the boat had two extra alternator belts in it. He replaced three belts the first season he had the boat. The next spring we replaced the alternator. That alternator lasted six seasons before it started acting up and continued to get worse this summer. So we put another new alternator on it six weeks ago. First time in the water with it, it was fine. Second time out it started squealing again on start up. This boat has a volt meter on it. When that belt is slipping it is not charging when it quits squealing it jumps up to about thirteen to thirteen and a half volts. I know that sounds like a loose belt. The belt tension is good and the belt is routed correctly. When this new alternator started acting up it was just for a couple seconds and now as we speak it takes min. Once the alternator starts charging and your running the engine everything is alright. When you shut the engine off and start it back up it squeals all over again. Something is causing these alternators to drag. I've spoke with to over fifty Marine mechanics and four service managers about this and have came up with nothing. That is why I tried Just Answer.
Expert:  Joe replied 1 year ago.

Randy, one thing I see is that even when it does charge it's only putting out 13-13.5 at best, ***** ***** in fact actually be putting out around 14v.

I would start myself at the time it squeals I would be disconnecting the wiring from the alternator and see if it then still makes the noise or not, this would eliminate the function/electrical of the alternator as the source of the problem, well, sort of.

can you tell me the part number of the newest alternator you installed?



Customer: replied 1 year ago.
Thanks Joe for sticking with me.
Were going to work on the boat Saturday.I'll try what you said and let you know. After that I'm going to take the Alternator off and have it checked. Check back with you tomorrow..
Customer: replied 1 year ago.
Joe, I wanted to catch you up on our problem. But first of all I'm having some trouble reading your e-mails. When I try to open them I get a message that says( The Web Address You entered could not be found) Now back to my problem. Ran the boat yesterday after making sure the belt was tight. We started it five times and all five times the belt slipped. Taking note of the gauge,all five times the showed charging 6 volts until the squeal stopped then the gauge showed almost 14V.
all five times. Took the alternator off, took it down to NAPA and had it checked. It showed good putting out 15Volts. So now we know it's not the alternator. Any more Ideas?
Thanks, Randy

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