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Old 18-08-2015, 10:48   #16
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Re: Alternator -- New or Rebuild?

I have had really good luck with having my alternators rebuilt. Find a good mom and pop shop where they do the work in house. They can also put in better parts than stock and increase the output if that is what you need. You can also buy a spare rebuilt for much less than you can a new one. This is especially true of Cummins parts which are almost as expensive as Volvo parts.
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Old 18-08-2015, 11:21   #17
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Re: Alternator -- New or Rebuild?

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Originally Posted by Dockhead View Post
Some of you may know from another thread on the subject that I fried my school bus alternator.

I have just arrived back in the UK after 3000 miles of sailing to Finland and back, and can now think about dealing with it.

I found a guy who will rebuild it, including rewinding it, for 120 pounds (plus VAT), about $230. Three day turnaround.

OR, he will sell me a brand new one for 290 pounds plus VAT, about $580.

Is there any good reason to spring for the new one, other than wanting to have the old one as a spare? The old one has 2300 hours on it and was working fine until I burned it up. Will it be as good as new after rebuilding, or should I spring for the new one? Grateful as always for your advice.
Most rebuilds are just diodes and maybe bearings probably oil lites.

Rebuilding windings? No one does that. That sounds like smoke.JMHO
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Old 18-08-2015, 11:40   #18
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Re: Alternator -- New or Rebuild?

The windings on the stator are replaced and not rewound. It is not cost effective for them to be rewound (unless your labor rate is 2 bucks an hour like you find overseas)

A good rebuild checks everything and replaces as necessary. It is not necessarily limited to the bearings and the rectifier.

On my last rebuild they replaced the bearings, rectifier and regulator. They also bead blasted the case. It looked brand new when done.
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Old 18-08-2015, 11:49   #19
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Re: Alternator -- New or Rebuild?

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The windings on the stator are replaced and not rewound. It is not cost effective for them to be rewound (unless your labor rate is 2 bucks an hour like you find overseas)

A good rebuild checks everything and replaces as necessary. It is not necessarily limited to the bearings and the rectifier.

On my last rebuild they replaced the bearings, rectifier and regulator. They also bead blasted the case. It looked brand new when done.
David,

I think what got me was rebuild the windings. Replace yes I wouldn't be sure, new isn't better way to go?
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Old 18-08-2015, 12:18   #20
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Re: Alternator -- New or Rebuild?

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Most rebuilds are just diodes and maybe bearings probably oil lites.

Rebuilding windings? No one does that. That sounds like smoke.JMHO

They still rewind motors and generators etc. but only the more expensive ones. The front bearing in an alternator is a ball bearing not an oilite bearing.
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Old 18-08-2015, 14:09   #21
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Re: Alternator -- New or Rebuild?

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They still rewind motors and generators etc. but only the more expensive ones. The front bearing in an alternator is a ball bearing not an oilite bearing.
Guy, maybe I was taking rewind literally. Just replacing windings I can see. Is there an economic advantage? It would seem replacing bearings, diodes and windings all that was reused was the housing and rotor possibly with a galled shaft? New assembled at two bucks a day labor seems cheaper, buy two, one back up. Maybe you said it expensive ones.
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Old 18-08-2015, 14:38   #22
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Re: Alternator -- New or Rebuild?

I sail offshore. I don't like rebuilds. I like new and I like spares. Comfort, safety and sense of security offshore is a plus for me. Just my 2 cents...
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Old 18-08-2015, 15:25   #23
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Re: Alternator -- New or Rebuild?

My vote is to get a new one especially if it has a written guarantee. But it's not my money.
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Old 18-08-2015, 16:48   #24
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Re: Alternator -- New or Rebuild?

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You bet. If he is doing even just one winding he will probably do bearings and brushes too. Maybe even a diode assembly. It would not be time to scrimp on a $20 bearing.
Guy,
That is a great call, the bearrings could have been damaged during the dis-assembly.
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Old 18-08-2015, 19:58   #25
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Re: Alternator -- New or Rebuild?

Over the course of a 10 year circumnavigation, we did not have great results on a number of rebuilds. We had rebuilds done in Mexico, Costa Rica and spain. Each of the three repairshops had differing opinions regarding rewinding methods, wire thickness and wire coating. None of the rebuilds were done to original specs. And none of the 3 rebuilds lasted more than a year. The original alternator went about 5 years before the first failure

All my alternators were the Balmar single belt models with an external smart regulator that was dialed back a bit to improve belt life. Dual belt setup is just not practical in our engine room.

When we got home from cruising, I bought a couple new Balmars and got rid of the failed ones.

Note: none of the repair shops did the work to make the alternator "like new" The cost to: rewind everything, replace all the diodes and replace bearings was not really a savings over a new alternator.
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Old 18-08-2015, 20:35   #26
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Re: Alternator -- New or Rebuild?

This from a person who replaces alternators almost daily OEM are the 1st choice very reliable, 2nd rebuild if done well? Don't wast money on the 3rd option after market they are made with cheap Chinese parts and will fail soon
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Old 18-08-2015, 22:18   #27
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Re: Alternator -- New or Rebuild?

"They don't replace everything, they rebuild them to specs that are as good as new."
Sorry, Guy, but according to one of the largest and most respected companies in the business, that is NOT TRUE.


Rebuild means "make it work again, fix what is broke".
When you are checking every part, and making sure it meets NEW PART tolerances, that is called REMANUFACTURING.


The industry is clear on this, but the public is arguably intentionally misled about it.


You burn out a diode, I replace it, it is now REBUILT. But unless I break the whole thing down, check every tolerance, impedance, and spec in it...it ain't remanufactured. Rebuilt, contrary to popular logic, just means "we found something broke and fixed it."
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Old 19-08-2015, 01:36   #28
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Re: Alternator -- New or Rebuild?

Why pay a different yokel to rebuild your alternator? It's not magic. You can order the parts from Amazon or E bay or probably a thousand other places. School bus alternator? So it's probably the same as a hundred thousand other alternators on all kinds of buses and trucks all over the land of the free. Don't know what you're doing? Ha! That's easy too! You don't have to know what you're doing. You don't have to get a degree in electronics. All you have to do is be able to Google " rebuild (fill in the blank) alternator. You will be led to You tube where you will find tens of guys who rebuild alternators for a living explaining the whys and wherefores of the process. Bearings? An overdose of videos explaining how. Brushes? Why test them? They are so cheap if you have taken the alternator off the vehicle, you might as well slap in a new set of brushes. Windings can be bought too. It it easy. I am lazy, but I am also a cheapskate. I found parts for my Jeep alternator on the Internet. The knowledge was acquired easily from watching about twenty how to videos. The testing part you can learn there too.Why not take the time to get some independence from the vultures? If you are gonna be out on the open road, don't you think you should at least try to learn some of this stuff so you don't get shafted every time you need service? It's not like you're going to do a lung transplant. A few hand tools and you will be good to go. And certainly... take spare parts. Bearings , brushes, diode plates. Take apart your alternator. Then you will see how easy it is. Take photos with your digital camera so you can put it back together. Match mark parts with a magic marker. Get a couple of pullers at garage sales. A decent Volt Ohm Meter. Now you're all set! Speaking of cheapskates, I had a heap which was like going to mechanic school. It needed alternator brushes. I got some electric drill brushes from a hardware store and cut them down to size with sandpaper laid on a flat surface. It worked. You can also solder the leads into graphite brushes. I have done it. Got me to work again in spite of being broke. If anyone disputes this, I will lay $5,000 on the table next to your $5,000. You can then lose your cash by watching me do it and establishing electrical continuity in my work!
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Old 19-08-2015, 10:43   #29
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Re: Alternator -- New or Rebuild?

Quote:
Originally Posted by Cadence View Post
Guy, maybe I was taking rewind literally. Just replacing windings I can see. Is there an economic advantage? It would seem replacing bearings, diodes and windings all that was reused was the housing and rotor possibly with a galled shaft? New assembled at two bucks a day labor seems cheaper, buy two, one back up. Maybe you said it expensive ones.
Well, I am pretty fanatic about spare parts on board. For example, I have a repair kit for every single pump on board, and a couple of spare entire pumps for critical things.

But you have to be rational about carrying spares, because it would be too costly, too bulky, and too heavy to carry spares for everything.

So I look at it from these points of view:

1. How likely is it to fail?
2. How difficult is it to repair or source out in the wild?
3. Is it mission critical, or backed up by something?
4. How bulky and/or expensive is it?

So I come out wrong for this particular item on all points -- very reliable, quite easy to fix even in third world countries (it's a common school bus alternator), it's not mission critical (I can use my generator), and it's fairly bulky and expensive.

Therefore, I have decided not to carry a spare.

I found a guy recommended by other cruisers, who is local to me and who specializes in alternator rebuilds. He replaces all wear parts (including bearings, etc.) and anything which is broken or sub-standard, and gives a year warranty.

Seems good enough to me.
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Old 19-08-2015, 10:58   #30
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Re: Alternator -- New or Rebuild?

If you have it rebuilt you can ask them to increase the amps output. I recently had the one on my motorhome rebuilt and increased the output to 200 amps and could have went up to 500 amps.

Or, they are not too difficult to rebuild yourself and buy a few of everything so you can make repairs anywhere

Good luck with it
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