Rebuilding an alternator

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Just note that most rebuild kits are from China. Unless, OEM. FYI.

*Some parts from China work well.
 
The better rebuild shops will use a lathe to turn the inside shaft (stator ??) and use an oscilloscope to check for the proper sine wave output. An alternator puts out 3 phase AC until converted to DC. They also have the experience to "feel" the shaft in the bearings and determine if a replacement bearing is needed.

What is wrong with the alternator? Often brushes are made easy to replace.
 
Mines a 33 year old Bosch. All it's ever needed are brushes. If your bearings are still good and the brushes are worn it costs about $5. I can do mine on the engine. I wouldn't buy a kit or a rebuilt. Just giving money away. Bearings and diodes are cheap too. Simple repair. Rebuilts from the auto parts store are a rip off.
 
Any idea how much are brushes and regulator are? Bearing seems to be good, I can freely rotate it.

No noise and grinding. Thank you.
 
Got it tested at a local shop and they said, diodes are bad and can be replaced for $40-$50.

Can I replace those diodes on my own?

Thanks for the help
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Originally Posted by andyd
Chances are, brushes and a regulator are all it needs


Sorry, too late to delete my response. Yes you can replace the diodes yourself but just take your time and don't rush it. Search the internet for a diagram or an excerpt from the factory shop manual.
 
Last edited:
Originally Posted by anndel
Originally Posted by andyd
Chances are, brushes and a regulator are all it needs


Sorry, too late to delete my response. Yes you can replace the diodes yourself but just take your time and don't rush it. Search the internet for a diagram or an excerpt from the factory shop manual.

Thanks, should I order brushes and regulator too or just the diodes?

Car has 186K on it.
 
I was helping someone with this on an Isuzu forum just an hour ago...

Brushes are about $4 after tax everywhere. Solder them in, no problem.

Bearings are $5 to $10. If the vehicle has a lot of miles on it, go ahead and replace it. (edit - 186k, change the bearings).

If you are not experiencing weird electrical anomalies (flickering warning lights, random shut-offs, etc), then your regulator is likely fine and you can skip it. You can do a simple test by looking for ac voltage across the battery terminals at idle. If none, and charging DC voltage doesn't exceed ~14.6 at any engine speed, VR is likely fine. The diodes are part of the VR, not separate.

Tons of DIY videos out there if you need help with any particular points.
 
Originally Posted by Oro_O
I was helping someone with this on an Isuzu forum just an hour ago...

Brushes are about $4 after tax everywhere. Solder them in, no problem.

Bearings are $5 to $10. If the vehicle has a lot of miles on it, go ahead and replace it. (edit - 186k, change the bearings).

If you are not experiencing weird electrical anomalies (flickering warning lights, random shut-offs, etc), then your regulator is likely fine and you can skip it. You can do a simple test by looking for ac voltage across the battery terminals at idle. If none, and charging DC voltage doesn't exceed ~14.6 at any engine speed, VR is likely fine. The diodes are part of the VR, not separate.

Tons of DIY videos out there if you need help with any particular points.

Thanks for helping out and for your advice.

VR(diode pack) is back, because have seen all flickering and variable voltage at battery terminal. Hence, replacing the alternator.

So clearly in that case, I need, bearings, brushes and regulator, right?
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Time is money. 40 bucks for a rebuild? Do it and come back to discuss oil. lol
 
Originally Posted by maverickfhs
Got it tested at a local shop and they said, diodes are bad and can be replaced for $40-$50.

Can I replace those diodes on my own?

Thanks for the help
thumbsup2.gif


Pay the money and make sure they replace the brushes also.
 
Places that let you Pick-N-Pull your own auto parts will probably have one for $25 - get yourself one


That way, you won't be in a rush to fix this one - you can take your time and learn at your own pace.

Then you'll have a spare when the other one goes out.
 
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