So 3rd alternator belt down and almost a summer wasted.........

[Nautiquehunter]

What brand of belt are you using ?

[djw383]

I used two different belts, with and without the notches. A Gates from Napa and one from Nautiqueparts.com. I believe the issue is the alternator is getting hot and then melting the belt. The alternator gets hot first, and quick, while the pulley stays cool until the heat radiates into the pulley. Identical from the 2013 post above, that’s why I was hoping to hear what the solution was from the dealer....

[bturner]

Typically when someone stops a post like this they've figured out the problem and just don't go any further with follow up as they're happy now, so let's move on.

I think it would be a somewhat safe to assume and very possible that the recommendations Charles suggested took him to resolution. Either way those suggestions on running down the cables would be sound problem determination procedures regardless. On a 25 YO boat I'd be really tempted to make new primary power and ground cables. These can go bad quickly in a boat and at a minimum I would be looking really, really close at these. The problem with these cables (especially if the have the lead automotive type battery lugs) is the connections can go bad due to corrosion that is running up the cable jacket which is difficult and sometimes impossible to see.

[shag]

Bturner is correct. Cables can look fine on the outside, but be deteriorated from the inside, and not be able to carry the amperage needed, potentially causing or contributing to the problem described

[THE HECKLER]

my 98 gt-40 was doing the same thing. there was a small area of rust/scaling on the inside of the grooves on the alternator and crank and water pump pulleys. I took some emery cloth and sanded on them until all of the "tits" were gone. Then I sprayed the surfaces with some boeshield and wiped clean. no more squealing or burned belts since. guessing yours still has some scaling or such on them too.

[djw383]

my 98 gt-40 was doing the same thing. there was a small area of rust/scaling on the inside of the grooves on the alternator and crank and water pump pulleys. I took some emery cloth and sanded on them until all of the "tits" were gone. Then I sprayed the surfaces with some boeshield and wiped clean. no more squealing or burned belts since. guessing yours still has some scaling or such on them too.

Pulleys look good! Well less than 1 minute the alternator gets real hot at idle, almost too hot to touch if you leave your finger on it. I then shut the motor off and check the pulley and it is cool...recheck, and the alternator continues to get hot and then transfer heat to the pulley.

[djw383]

I also tried another Battery....

[Mikeski]

There are two kinds of mechanics (using the term loosely), technicians and parts changers. Most mechanics these days fall into the latter category. They plug in a computer, it tells them what to change, they change the part. This type of issue requires a technician. With proper meters and process these types of issues can be diagnosed without much guesswork, shameful the dealers cannot provide this service for these not so complex machines.

A voltage meter and DC ammeter can show exactly what is happening with they system electrically, this should be done first. The electrical components can be isolated and diagnosed independently then reconnected and diagnosed as a system. Batteries at rest should be between 11.6-12.7V and between 13.2-14.5 when charging. Charging current should be in the 10-50amp range once initial inrush has passed. Double check to insure all system components are wired with proper polarity. Check batteries to insure they are supplying proper polarity (I have seen an inverted battery where the positive and negative have been reversed).

Mechanical tests, remove the belt and spin the alternator. It should spin with a limited but constant resistance. Free spin would indicate the bearings are shot. Listen for ticking, scraping, or ringing, all signs of mechanical issues within the alternator. Is there an external regulator? If yes, remove the cover and examine for bad contacts or mechanical issues.

Temporarily disconnect the stereo and lighting systems, test to see if the issues happen when these systems are disconnected. Measure currents going to these systems. Verify proper polarity on these systems. Double check cables to make sure they are not shorting to each other or grounded metal components.

Lastly, issues found in one boat may or may not be helpful finding issues in another boat even if the symptoms appear to be similar.

[djw383]

All really good points, thank you!

[djw383]

I messaged CUE99T to see what the dealer said, it shows he was active last on 7/3/21 so there is a good chance he will see my DM. I will put a meter on the cables tomorrow and let everyone know the outcome....thank you everyone!

[djw383]

To finish this post, the issue was the battery cables. When we swapped them out, we sliced the cables open and they looked fine, and the cables even tested ok with a meter. However once you dug into the center the copper was very corroded. Thank you for everyone’s help! Enjoy the rest of summer.