Loose Bolt on Altenator

[OrangeCrush]

Hello,
I noticed a loose bolt on one of my two Balmar alternators. It seems to be stripped in there, or maybe never really threaded in the first place? Either way it will not tighten and I see almost no threading inside the hole, unless it's deeper than I can see in. The whole boat is new to me so not sure how long it's been like this. It is on the "hinge" side, and with the opposite bolt snug and the bolt on the adjustable tensioner also good, nothing on the alternator seems to be moving even with this one completely loose. The belt is still nice and tight, for example. The yellow wire, however, is no longer in good contact with whatever it was grounding to. I have also noticed much lower amperage output than it's supposed to be giving me, so maybe the whole alternator is "offline."

So, should I....
1) tap a new thread in the hole and use a lock washer this time
2) remove the bolt altogether since it seems a but redundant and route the wire to another spot on the alternator?

Or is it possible there's something I'm not understanding about how the alternator is mounted?

Any advice is appreciated and thanks for taking the time to respond.





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[smac999]

you defaintlly can not remove that bolt. it's the main mounting bolt. put a nut on the other end of it.... or get a longer bolt if it's not long enough for a nut.

[Seeking Solace]

Originally Posted by smac999

you defaintlly can not remove that bolt. it's the main mounting bolt. put a nut on the other end of it.... or get a longer bolt if it's not long enough for a nut.

Exactly! Looks like the nut just fell off of it or was never put on there to begin with. It is using that pivot point as it's main mounting bolt. Looking at the picture it seems to be all the way through, just add a nylock nut or any nut that fits with a lockwasher. The belt isn't getting loose because that end of the alternator isn't moving.

Don't see a "yellow" wire. If it was on that bolt, it is a ground wire (why yellow?, perhaps a marine ground color?)

[smac999]

yellow is current standard for DC neg on boats in north america. black is old standard.

you just just see the edge of the yellow wire sticking from under the black heatshrink. it's the main alt neg.

[Symphony]

Where is the other end of th yellow wire attached?

[SeaSon]

You need a wrench on either end in order to tighten the nut onto the 'trough the alternator' mounting bolt.

[OrangeCrush]

Thanks for the replies. I have to admit I didn't investigate as well as I could have before posting this one. I noticed the issue right before I had to leave the boat after haul-out and snapped the picture in the hopes of figuring it out afterwards. I didn't follow the yellow line to see where it goes, nor did I take out the bolt on the other side to inspect.

It would make sense that the bolts go straight through the mounting tube, but I still can't quite picture how the two would connect in the middle unless one fits inside the other. The yellow wire being the main alternator ground would make sense, especially since it seems like I wasn't getting full amps when it was loose. Regardless, I'll make sure to resolve this before I use the motor again.

Thanks for the help as always, Jack

[SeaSon]

Originally Posted by OrangeCrush

Thanks for the replies. I have to admit I didn't investigate as well as I could have before posting this one. I noticed the issue right before I had to leave the boat after haul-out and snapped the picture in the hopes of figuring it out afterwards. I didn't follow the yellow line to see where it goes, nor did I take out the bolt on the other side to inspect.

It would make sense that the bolts go straight through the mounting tube, but I still can't quite picture how the two would connect in the middle unless one fits inside the other. The yellow wire being the main alternator ground would make sense, especially since it seems like I wasn't getting full amps when it was loose. Regardless, I'll make sure to resolve this before I use the motor again.

Thanks for the help as always, Jack

Now it sounds like you have 2 short bolts from either end, there typically is one long bolt with a nut and washers on the end.

[Sailmonkey]

In your picture I'm seeing what looks like a loose nut on the end of a bolt through the pivot point.


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[OrangeCrush]

Originally Posted by SeaSon

Now it sounds like you have 2 short bolts from either end, there typically is one long bolt with a nut and washers on the end.

Yes this is the case. Sorry if the picture or description were unclear. It's two shorter bolts (or would you call them machine screws?) with no nuts. One bolt is loose and will not tighten. It's about 3" long so it probably reaches right to the middle of the tube bracket. I'll remove and inspect the bolt on the other side. Since at least the one side seems to have insufficient threading to hold the bolt tightly, I will probably replace it with one long bolt straight through with a nut/washer/lock washer.

[Blue Stocking]

That alternator has what is called a saddle-mount style. That is, an ear on both the front and rear castings. The sleeve between the ears is to prevent you from over tightening, and breaking off the ears. The small brass sleeve in the rear ear can to pushed out a bit to allow easy assembly, and is then drawn in tightly by the bolt and nut.

[OrangeCrush]

Originally Posted by Blue Stocking

That alternator has what is called a saddle-mount style. That is, an ear on both the front and rear castings. The sleeve between the ears is to prevent you from over tightening, and breaking off the ears. The small brass sleeve in the rear ear can to pushed out a bit to allow easy assembly, and is then drawn in tightly by the bolt and nut.

Ah ok... very useful info, thanks. So perhaps the brass sleeve has shifted so the rear bolt can't reach the threading? With this new info I think it will be clear how to put it back together correctly once I get down there again. I still think a lock-washer is in order since vibration may have been the original culprit.


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[OrangeCrush]

At this point I won't be running the motor until Spring to know for sure, but what are the chances I burnt out diodes or otherwise damaged the alternator if the main ground wire was loose?

Thanks again.

[Seeking Solace]

Originally Posted by OrangeCrush

At this point I won't be running the motor until Spring to know for sure, but what are the chances I burnt out diodes or otherwise damaged the alternator if the main ground wire was loose?

Thanks again.

You'll drive yourself crazy worrying about the what ifs. Once you have the bolt back on there and the ground wire attached you can just test the alternator. If you don't have the knowledge or means you can always take it to one of the chain auto parts stores and have them load test it. They don't usually fail half way, typically in my experience they work until they don't. It may not have been able to transfer all the power it was making, but even that is unlikely.

You might want to think about keeping a spare if you don't already have one. They seem to be an item that is prone to failure in that environment. They can get expensive, so shop around if that's what you intend to do for the future. Spares are always in the way too, so best to keep it in a good dry location sealed up in a bag.

My best guess is it's fine until it proves to not be fine. So, if you're going to wait until next spring to test it, sleep well until that time comes. Remember that it's part of a system and not self reliant. There are lots of factors that can change it's performance, including poor connections, deteriorated wiring, failing regulators, and batteries that have reached the end of their life cycle just to name a few. Like anything else, it won't last forever. It's good that you're at least trying to make sure it last as long as possible.

(Just FYI there's only 2 ways I know of killing a diode. Overvoltage in the forward direction and exceeding it's Peak Inverse Voltage)

[OrangeCrush]

Originally Posted by Seeking Solace

You'll drive yourself crazy worrying about the what ifs.

But if I don't drive myself crazy stressing about boat maintenance how will I manage to avoid my real job?! Thanks, that is sound advice. You may be seeking solace but you can dish it out as well.