Has anyone rebuilt their alternators themselves?

[Kruse]

Originally Posted By: Texan4Life
but the article recommended a special screw driver you hit with a hammer (forget what they are called).


Pretty sure you are thinking of an impact driver.
I've rebuilt many in my life, but it's getting harder to find quality replacement parts. As mentioned, some of them are soldered in place and are not really meant to ever be reworked by a do-it-yourselfer. I've talked to a local rebuilder and he's telling me that more and more of them have to have the replacement alternators purchased instead of rebuilt. It's a throwaway society. I tried to get replacement parts to rebuild the starter on my Jeep last year and every local place just laughted and told me that they hadn't sold any alternator or starter replacement parts in years. RockAuto listed them, but I needed the starter fixed immediately so I just bought a replacement from an auto parts store.

 

[mechtech2]

Kestas -
The deal killer is worn brass slip rings. [I mean worn to far.]
At about 100k,you should be good.
Basically,you are replacing bearing and brushes. A new regulator with brushes is a good idea.

 

[Donald]

Originally Posted By: Kruse
Originally Posted By: Texan4Life
but the article recommended a special screw driver you hit with a hammer (forget what they are called).


Pretty sure you are thinking of an impact driver.
I've rebuilt many in my life, but it's getting harder to find quality replacement parts. As mentioned, some of them are soldered in place and are not really meant to ever be reworked by a do-it-yourselfer. I've talked to a local rebuilder and he's telling me that more and more of them have to have the replacement alternators purchased instead of rebuilt. It's a throwaway society. I tried to get replacement parts to rebuild the starter on my Jeep last year and every local place just laughted and told me that they hadn't sold any alternator or starter replacement parts in years. RockAuto listed them, but I needed the starter fixed immediately so I just bought a replacement from an auto parts store.


A local shop in Albany only does big ones for bulldozers, etc. But he was happy to test the one for my Bobcat. His shop has not changed in probably 30 years. He does have an oscilloscope, but its probably a tube one.

 

[hsd]

Ive done some rebuilds in the past, just brushes and bearings. Mostly on my "classic" cars where I wanted to keep the OEM alternators original. Once had an 88 Cavalier with a throw away alternator which could not be taken apart without destroying the case.
My current Honda alternator brushes can be changed without even removing it from the car, so I carry a spare brush set in the glove box. My experience has been, if you carry a spare, that part will never fail

 

[danthaman1980]

Any half decent alternator rebuild should include new brushes, new bearings, new diodes/diode bridge assembly, and an new regulator (if internally regulated). A better rebuild will replace your slip rings or install a new or rebuilt armature.

Try to find a shop that will rebuild your alternator while you watch - tell 'em you want to see how it is done because you were thinking about doing it yourself but just weren't sure if you could.

I've watched my alternator get rebuilt twice... brushes and regulator are typically super easy. Diode bridge can be a lot harder because it takes a very large, very powerful soldering iron to remove the bridge (I guess you could use a small butane torch, as long as you're super careful). Bearings are a PITA unless you have a press. Slip rings are best left to a professional.

 

[Vikas]

realistically, the only thing which really wears out are the brushes at least for the 1st pass i.e. you would likely get double the lifetime just by replacing the brushes. On your second brush replacement you should be looking at the other wear items.

At least that was my experience with Nippon Denso starter contacts which are sort of similar to brushes in the alternator.

 

[Quest]

I've rebuilt numerous Denso alternators with great success (mostly replacing the brushes, no need to replace the otherwise excellent shape rectifier pack).

I had limited luck dealing with Mitsu alternators.

I had good luck with Hitachi alternators as well.

Q.

 

[RonH]

I just rebuilt my Ford 3G alternator from the 97 F350 Diesel. It went real smooth, cost $35 or so. I'm more confident keeping my original than I am buying a rebuilt that came from who knows where originally.

 

[zzyzzx]

I replaced the diode pack on my Alero's alternator:
http://www.aleromod.com/forums/showthread.php?t=32281

Brushes should be pretty easy to do too.

 

[Vikas]

how likely diodes are to die? the entire idea behind having solid state components is to avoid aged obsolence. Electrons don't get tired! There are some electronic components which do exhibit end of life such as capacitors etc but diodes should not.

Any electronic engineer to chime?

 

[Kruse]

Originally Posted By: Vikas
how likely diodes are to die?


I would say that some of the smaller alternators that have a somewhat high output have had diode problems in the past, especially where most of their life has been in rush hour traffic. Some of the GM products come to mind.

 

[mechanicx]

Diodes are the most common thing to go out and cause alternators to stop working.

 

[Vikas]

If that is the case, then if you are going to do preventive maintenance, at least use the OEM quality or better diodes.

anybody found authoritative study on lifetime of typical diodes used in automotive alternators? all the references were for laser diode where they were studied for lifetime.

 

[zzyzzx]

Originally Posted By: 01rangerxl
I never really thought about rebuilding an alternator myself. Out of curiosity I decided to see if there was a kit for my truck, and there is...if you live in Mexico. Auto Zone sells an alt rebuild kit for my truck from a brand called "Victory Lap," but there is a note that it is for Mexico stores only and instructions are in Spanish. Won't give me a price or allow it to be shipped to the US.


You can buy alternator parts elsewhere. I bought mine on eBay.

 

[zzyzzx]

Originally Posted By: Vikas
how likely diodes are to die? the entire idea behind having solid state components is to avoid aged obsolence. Electrons don't get tired! There are some electronic components which do exhibit end of life such as capacitors etc but diodes should not.

Any electronic engineer to chime?


The diodes on mine died. Another one I did in the late 80's also had bad diodes. Yes, i used to be an electrical engineer, but for my sample of 2, both needed alternators.

 

[Kestas]

Would it be worthwhile to consider upgrading diodes to something beefier, thus precluding future diode failure?

 

[cchase]

Originally Posted By: Vikas
If that is the case, then if you are going to do preventive maintenance, at least use the OEM quality or better diodes.

anybody found authoritative study on lifetime of typical diodes used in automotive alternators? all the references were for laser diode where they were studied for lifetime.


Diodes die due to heat or excessive current. There's nothing about solid state components that says anything about the ability of components to take "abuse" or "extreme" environments. The diodes in a vehicle alternator have to put up with extremes of temperatures, shock, vibration, and potentially high loads under unique circumstances (idling in the summer with every accessory going and a dying battery, for example).

Dead or dying diodes and capacitors kill many an otherwise serviceable appliance in almost every part of daily life.

 

[bullwinkle]

I have a guy down in Maysville, KY who has rebuilt them for me before (he did bearings and brushes in the '89 F-450 for $25)-I am going to have him do the Jeep 4.0 alternator next (@ 210K it's overdue), place is called Maysville Generator.

 

[mechanicx]

I agree. Solid state electronics are generally more sensitive to heat than the older vacuum tube technology I think. Of course vacuum tubes aren't practical and they could fail too. Bottom line, solid state diodes in alternators fail fairly regularly. Although nowadays they seem to often last over 10 years and over 100k miles. It's hard to predict service life, just that diodes are the likely suspect when an alternator does fail.

 

[zzyzzx]

Originally Posted By: Kestas
Would it be worthwhile to consider upgrading diodes to something beefier, thus precluding future diode failure?


I would think so, but I would also think that heat and vibration would ruin higher amperage rated diodes just the same. They would do better under more electrical stress.