[ATX_Diablo]

Hey all,

The alternator in my 94 Diablo, 4.3 I/O is making bearing noises and I'm planning to just replace it with new.

The original is p/n 817119, apparently made by Mando, with V-belt (not serpentine), 55 Amps. It has a jet black painted finish.

There is a dizzying array of possibilites on-line. I found plenty that claim to replace the above but look slightly different. I also find some that have the same black painted finish but are p/n 817119A-4. The latter cost about $50.00 more than the former or so.

Mercury - Quicksilver Alternator Mando 55 Amp 817119A-4 - Alternators - JMSOnline.net Marine Supply and Boating Store

I would like a "real" Mercury part.... any idea if the A-4 is the modern replacement for my orignal - or what the differences are?

Any input appreciated.

[ColoradoDiablo]

Part #817119A4 is the "New" replacement for your original #817119A1.
Checked..........and at the very least , 92-96 4.3's are all the same Mando 55 amp alternator. I'm sure they are the same a l earlier too , but the later serpentine alternator (Gen V engines) are different.
So yes , in a nut shell the 817119A4 is the one you want.
Stick with the original so you have no "modifying" issues.
PS: That ain't a bad price in my opinion.

[Hudson River Steve]

I can't tell from the Mercury part number which Mando model you have but if it is only bearing issues why not just replace the bearings. I have used an online bearing house in the past VXB.com Ball Bearings:Miniature bearings:Ceramic Bearings just measure your ID, OD and thickness and you should be able to fix it for just a few bucks.
If you want to go an extra step you can always purchase a rebuild kit which includes the bearings, brushes and sometimes the regulator similar to this Mando Marine Alternator Repair Kit | eBay?

This way you know what you have is correct.

[ATX_Diablo]

Thanks for the input guys!

I did not order the 817119A4 yet. I'm going to run the boat some more on the "ear muffs" this weekend and see how it does.

As far as just replacing bearings or rebuilding it, I've done car alternators before with mixed success. The age of the windings, rectifiers, etc. is getting up there and I think going with new may pay off in the long run. I might rebuild the old one in my spare time for a spare ( )

At first I thought the voltage was low based on my gage in the panel. But when I put my hand-held Greenlee multi-meter on it, it was reading about 13.2 volts, while the boat gage showed less than 12 when the boat was running at 1500 RPM or so. The voltage per the multi-meter was about 11.5 with the boat engine off. Those readings tell me the alternator is charging.

I pulled the boat gage, and hooked it directly across the battery with the boat running and it showed 13.2 volts like the hand-held.

Apparently, the wiring between the gage and baterry has a voltage drop.... I'm thinking bad connections. I plan to dig into it this weekend. Any ideas / suggestions welcome.