Do you have belt or blower drive alts?
If belt drive, just pull it off.
IF blower drive, be aware of a few things...... first, there's a hub between the blower coupling and the alternator that has an oil seal in it. Those like to leak when disturbed, and even if just looked at wrong. The leak isn't bad, but its a damn mess and gets all over the gear. The only real fix is a "hub kit" which runs about $100 - and if you booger the seal on install, its junk and you get to do it over.
You CAN press out the old seal and press in a new one, but it requires an arbor press and must go in EXACTLY straight or it will leak. Then again these often leak even when brand new - so its six of one, half-dozen of the other. Sometimes you get the good end of the deal, sometimes not....
This is the one "lots of 4 letter words" leaks on the 6V92s that is basically impossible to prevent over time.
Notes on this...
Before removing the alternator, make sure the high amp (ANL) fuse and wiring are good. Note that on a LOT of Hatts ALL the heavy-gauge wiring was done with UNTINNED wire and over many years it will corrode internally and stop working, even though it LOOKS fine. If you can't flex the wire easily, its screwed no matter how it looks. Open the electrical panels and look - the fuses are marked. On most Hatts with a 12V system the alternator fuses are 80 amps. WARNING: Large parts of that panel and the Alternator primary leads are HOT even with the master switches OFF, and big parts of it are hot with a connection of 4/0 back to the batteries! Shorts WILL weld your tool(s) to the panel and cause severe damage, including the possibility of fires or electrical explosions. Either disconnect the batteries or be EXTREMELY careful - if you disconnect batteries check to insure that the panel is cold with a VOM before proceeding.
To remove the alternator on a blower-drive engine disconnect the electrical connections (tape the ends and secure them - see the above note about them being hot!) then remove the bolts. The alternator will pull straight back and out. There is a coupler disk that engages the alternator and blower adapter drive pins to make the actual connection.
To replace, line up the pieces and insert straight in, then re-bolt it up. Use a new gasket. Make sure you do not place load on the coupler (don't let it "hang" from the bolts when re-installing) to avoid damaging it and having a premature failure. They're somewhat of a pain to reinstall single-handed, but I've done mine before (I have the blower-drive models)
Don’t run the alternator with the battery disconnected...
That could blow the alternator.
My port 871 is behaving the same way. It is most likely my wiring. That needs to be check first.
Genesis, an automotive load tester could be used across the alternator to check it right?
Greg
I'm not so sure it isn't the battery(s)...
In my opinion, an alternator going bad by sitting around for a while is rather unlikely. If the alternator will deliver 15 volts at 1500 RPM, this, in my mind, tends to point to the battery, not the alternator. I realize you checked the batteries but this symptom, is typical of a battery that will not hold/deliver it's rated output.
Normally, the battery is supplying the power, NOT the alternator. The alternator simply charges and maintains the battery so IT can provide the power necessary. However, if the battery is not able to deliver it's rated power for some reason, then the alternator will try to pick up the load. The typical symptom for that is lights brightening or voltage rising considerably as the RPM rises. It doesn't happen if the battery (and charging system) are working properly.
You can load test the battery or the alternator but that requires equipment which is not normally in the DIY toolkit. A multimeter can measure the voltage which is very easy but it can't measure sufficient amperage to be any use. You need a load tester which can measure hundreds of amps. Any mechanic shop would have one of these if you have a friend in that business...
If it isn't too difficult, I'd try a known good battery - preferably a new and freshly charged one and see what happens before I'd mess with removing/disassembling the alternator. I'm not saying it can't be the alternator but I am saying that it is not the first place I would look. Batteries can test fine with a hydrometer and a voltmeter and not deliver their rated power. Load testing is one way to be sure but substitution is a pretty good and time-honored method as well.
In any case, let us know what the problem was when it was corrected and good luck for an easy and cheap repair!
I'm not so sure it isn't the battery(s)...
If the alternator will deliver 15 volts at 1500 RPM, this, in my mind, tends to point to the battery, not the alternator. I realize you checked the batteries but this symptom, is typical of a battery that will not hold/deliver it's rated output.
Normally, the battery is supplying the power, NOT the alternator. The alternator simply charges and maintains the battery so IT can provide the power necessary. However, if the battery is not able to deliver it's rated power for some reason, then the alternator will try to pick up the load. The typical symptom for that is lights brightening or voltage rising considerably as the RPM rises. It doesn't happen if the battery (and charging system) are working properly.
As Jim R. and Genesis mentioned, you can load test the battery or the alternator but that requires equipment which is not normally in the DIY toolkit. A multimeter can measure the voltage which is very easy but it can't measure sufficient amperage to be any use. You need a load tester which can measure hundreds of amps. Any mechanic shop would have one of these if you have a friend in that business...
If it isn't too difficult, I'd try a known good battery - preferably a new and freshly charged one and see what happens before I'd mess with removing/disassembling the alternator. I'm not saying it can't be the alternator but I am saying that it is not the first place I would look. Batteries can test fine with a hydrometer and a voltmeter and not deliver their rated power. Load testing is one way to be sure but substitution is a pretty good and time-honored method as well.
In any case, let us know what the problem was when it was corrected and good luck for an easy and cheap repair!