Alternator life expectancy.
 

What do you think the normal life expectancy for alternators are ? Mine is 27 years old with 635 hours on it . It's still charging . This weekend at around 1000 tons I started to hear a little cleatering coming from what sounds like the front of the engine on one of the pulleys. Other then the noise, which goes away or isn't as noticeable at higher RPMs . I'd prefer to be proactive then end up inactive, like the middle of the river . Taking the belts of and spinning it doesn't really revival much . Any thoughts ?

Re: Alternator life expectancy.
 

Your engine has two belts? If so, take one off and check again.

I would probably change the tensioner/pulley first, as these seem to fail quicker and more often. But even the alternator isn't very expensive or difficult to replace.

But then I am not real familiar with the 1990 engines. Maybe there is no tensioner?

Re: Alternator life expectancy.
 

Yes it does have two belts. One to the power steering pump and one to the alternator

Re: Alternator life expectancy.
 

I would suggest that 1000 hours might be close to the half life of a component like this. 2000 hours is the equivalent of 100,000 miles at 50 mph and most automotive alternators should easily do that.

I'll also tell you I once had the belt go with no spares. No alternator and no water pump. Foolish of me. But the battery will run the engine for a long time if you are not starting and stopping and using the battery power for much else. Easily an hour or two.

Can't say on the V8's but on my 4 cylinder if you keep the rpm's low in the range, maybe 1500-2000 where you might not get on plane, the impeller pump in the outdrive will keep the engine cool enough to prevent any over heating.

This happened to me years ago and we basically took a leisurely idle ride back to the dock with me watching the temp gauge closely and feeling the exhaust manifold from time to time to make sure we were not overheating and cooking something. Everything was just fine.

So I think you should be able to get somewhere if your alternator goes and you have to remove the belt to keep it from self destructing something.

In the aftermath and repair I discovered a couple thing. The pulleys like to rust and the alternator on mine was getting a little noisy. My alternator was still looking like new with <75 hours but one of the bearings was already a bit noisy. It was a pain to get the thing apart but I just put new bearings in it for a few bucks and it has been fine since. I spent a lot of time also cleaning the rust from the pulleys because that is what ate up the belt.

The real source of the whole problem was not keeping it dry dry in storage over the winter. Some water in the bilge meant condensation particularly in the engine compartment on the cold steel that rusted the bare metal pulleys. Maybe the bearing was corrosion or maybe just a random failure, IDK.

I should add that some alternators have very durable windings good for many rebuilds. New bearings and regulators make them as good as new. Not sure about these overpriced 'marine' alternators which I think are just automotive ones painted Phantom Black :)

Re: Alternator life expectancy.
 

Best bet is to buy yourself a cheap mechanics stethoscope for $10 or $15. Use it to isolate the noisy bearing rather than guessing which component is bad and throwing money away which can be better spent on adult beverages.

Re: Alternator life expectancy.
 

Personally mine lasted to about 400 hours. I would try to tighten the belts or replace them.

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Re: Alternator life expectancy.
 

I would try tighting the belt or just buy a new one.

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Re: Alternator life expectancy.
 

Is there any rust on any of the pulleys? I thought I was losing a belt once but it was just rust where the belt ran on the pulley. A little sandpaper and a rattle can of engine enamel​ and she was quiet as a mouse. Just a thought.

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Re: Alternator life expectancy.
 

I don't know what a "cleatering" sound is. Is it possible one belt is slipping when it gets hot and expands? Try checking the belt tensions.

Re: Alternator life expectancy.
 

Going to try the mechanics stethoscope. Everything is tight and the belts are new. The tensioner and power steering pump are all kind of the same thing . Haven't had it in the water since this post so hopefully this weekend I'll have answers