Rebuilding Yanmar (Hitachi), 12V 60amp Alternator

[BigEasy]

I carelessly shorted my alternator & now attempting to rebuild. The continuity of the stator & rotor windings check out normal. No evidence of overheating or burnout visible. Have traced the problem to diodes & perhaps the internal voltage regulator. Fortunately, I have sourced a compatible module that has new diodes, brushes, & regulator that is pre-assembled for a very reasonable price, especially when compared to a new Yanmar alternator at $800! Presently awaiting delivery of parts. The module assembly is shown in the photo sitting atop the stator.
Any insights would be welcomed, just don't ask how I damaged the alternator!
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[JoeWhite]

Looks good. To protect the alternator from future damage from loss of ground, install #8 cable from the ground lug of the alternator to the shunt on the opposite side of the shunt's battery connection.

 

[dlochner]

Fortunately, I have sourced a compatible module that has new diodes, brushes, & regulator that is pre-assembled for a very reasonable price, especially when compared to a new Yanmar alternator at $800!

There is no need to buy a Yanmar branded alternator, there are plenty of better alternators out there for much less money that fit a Yanmar. I have 2 of them and an older 80a Hitachi. Two of the alternators were better than the stock Yanmar alternator and cost about half as much.

 

[BigEasy]

There is no need to buy a Yanmar branded alternator, there are plenty of better alternators out there for much less money that fit a Yanmar.

Dave,
I have located two alternators that are Hitachi clones; one manufactured in Japan & one manufactured in Germany. Both are approximately $500 including shipping. I would expect the quality to be equal or better than the Yanmar. Hesitant to use the Chinese alternators listed on EBay & Amazon. If I can successfully rebuild my present unit for the cost of the $65 repair module, that would be awesome!

 

[Hayden Watson]

Call Tucson Alternator Exchange and tell them what you have and they can get you set up. If you are internally regulated, the only important thing they need to know is what type of mount you have and if your tack gets its signal from the alternator or not. If you just want to rebuild your current one, they can also do that although it would probably be cheaper to do that at a local auto-electric shop.

Last year, they built me a custom configured 250A Denso large frame externally regulated 250A with tack tap for $375 out the door and it is working perfectly. I get a constant 190A out of it from my 23hp Universal M25XP.

 

[BigEasy]

Looks good. To protect the alternator from future damage from loss of ground, install #8 cable from the ground lug of the alternator to the shunt on the opposite side of the shunt's battery connection.

Thanks Joe,
I have that cable that connects on the outside of the alternator rear case that houses the stator & electronic components. Not visible in the attached photo, but have another photo of it along with notes to reassemble correctly!

 

[BigEasy]

Call Tucson Alternator Exchange and tell them what you have and they can get you set up.

Much thanks, If my repair is unsuccessful, I will give them a call.

 

[dlochner]

Much thanks, If my repair is unsuccessful, I will give them a call.

That's probably a good bet. The price of alternators has gone up significantly since I last shopped for one. Yanmar branded products are usually much more expensive than the same product without the Yanmar name. I just purchased new motor mounts from Ellebogen at half the cost of Yanmar mounts the same size and shape. If you can't rebuild the alternator, go with Hayden's recommendation.

 

[BigEasy]

That's probably a good bet. The price of alternators has gone up significantly since I last shopped for one. Yanmar branded products are usually much more expensive than the same product without the Yanmar name.

Funny that you mentioned the motor mounts. Just completed installation of four Ellebogen mounts last week; less than 1/2 the cost of Yanmar. Quality appears to be excellent.

 

[BigEasy]

install #8 cable from the ground lug of the alternator to the shunt on the opposite side of the shunt's battery connection.

Joe, I think that the cable that you mentioned is highlighted in RED on the rear alternator case. Is that correct?

 

[JoeWhite]

BigEasy, I do not think that is the ground lug. If i had to guess i would say that it is the lug just below the one marked at 4 o'clock pisition. This lug has no nut on it.To locate the ground or negative side, make a resistance measurment from the outer case to the ground lug. It should be zero ohms. Reverse the voltmeters leads and repeat the measurement and it should be zero aswell.
In most installations ground is provided through the installation hinge bolts that are bolted to the engine block. But these are not a reliable way to provide ground to alternator, as only a microsecond of loss of ground will damage the diodes. The lug i picked has no nut on it, confirming that it was installed without a grounding wire.

 

[BigEasy]

To locate the ground or negative side, make a resistance measurement from the outer case to the ground lug. It should be zero ohms. Reverse the voltmeters leads and repeat the measurement and it should be zero as well.

Thanks Joe, I will test it per your advice when I get it reassembled. Much appreciated.

 

[JoeWhite]

BigEasy, visit here to read about my experience with this need to install the ground wire.

Alternator Bracket | Sail La Vie

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