How can you freshen up the alternator?

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by bazar01, Apr 13, 2012.

  1. The Heater

    The Heater Member 2 Years 100 Posts

    Hello, Bazar01:

    You can absolutely rebuild your alternator. Do not get a remanufactured one, rebuild yours.

    Having said that, I firmly believe in having them rebuilt by those who do it for a living and possess the fund of experience and knowledge to make sure all issues are addressed in the rebuild. They have equipment that is way to expensive and not practical for a homeowner to buy. They would be testing the rectifiers, for one thing. There are ways to see if they are starting to fail, for example. When one of those goes, the alternator cannot recharge your battery or supply the correct current to supply your vehicle's needs.

    Another thing they would do is test the output of the alternator under a load and without a load, and perform tests to make sure it functions properly.

    Lastly, they can tell if the armature needs to be turned, which usually is a good idea, or whether it is too worn to turn, in which case it must be replaced. Simply replacing brushes does not give you a free pass out of jail on this particular issue. The armature (or stator) has windings. These heat up and the insulation can melt or otherwise deteriorate with age, causing the armature to malfunction. Usually it manifests itself as lower output, not necessarily a complete failure.

    So as you can see, you can backyard this project, sure. But why even spend your own valuable time on it if you miss something and this thing pukes on you half way up Pikes Peak or Siskiyou Pass? Or coming home in a rain storm?

    You should have an auto electric shop somewhere around where you live that will take those parts you ordered and test this thing and put in your parts for you and give you something that is sure to work for as you say "another 100K".
     
  2. bazar01

    bazar01 Member 2 Years 100 Posts

    Thanks for the suggestions.

    I know my limits. If upon opening up and I see a damage that will need machining (worn bearing housing and journals), sure i will just take it to an alternator shop. But if the bearing housings and shaft journals are fine, the slip rings are not gouged due to worn brushes and rectifier is good (just a set of diodes that can be tested with a meter), I can just replace the bearings, regulator and brushes. Of course the slip rings can be polished with a 800 sand paper. If the slip rings are worn, it is also available online and just a matter of unsoldering and sliding the old one out and sliding the new one in and soldered.
    My alternator right now is fine but with 150k miles with no bearing noises, voltage output at 14.5VDC on the gauge, I am pretty sure the carbon brushes are getting worn close to the pigtails. Once the carbon brushes pigtails hit the slip rings, that's the end of it. And that is what i am trying to avoid on this refresh while the alternator is still working fine.
     
  3. janikphoto

    janikphoto Rockstar 3 Years 100 Posts

    I'd consider buying one at a junkyard and practicing on it. If I succeed, I have a great back-up one. If I fail, I still have a truck that drives...
     
  4. bazar01

    bazar01 Member 2 Years 100 Posts


    I wish there is a pull-a-part close by. I am pretty sure they will still charge an arm.
    My parts will arrive on Tuesday, I'll see if there are any issues doing this at home.
     
  5. janikphoto

    janikphoto Rockstar 3 Years 100 Posts


    I've found a ton of good yards here that were filled with my era trucks and suburbans. I could probably find my practice alternator for a good price...
     
  6. bazar01

    bazar01 Member 2 Years 100 Posts

    The parts came in yesterday, 2 days earlier than expected.

    Anyway, I won't be able to work on it until Monday. I'll post the update and take lots of pictures.
     
  7. bazar01

    bazar01 Member 2 Years 100 Posts

    Came home early today and the weather is extremely nice, why not work on the alternator?

    Tools needed:
    1. 5/16 nut driver, top engine cover and hose clamps
    2. 17 mm socket, alternaotr mount bolts
    3. Ratchet handle 1/4" and 1/2" drive
    4. 17 mm combination wrench, belt tensioner
    5. 21 mm wrench as cheater for belt tensioner
    6. E6 torx socket, alternator brush and regulator bolts
    7. 10 mm socket, alternator + cable

    1. Remove engine top cover
    2. loosen clamps and remove air intake snorkel
    3. Unplug alternator 4 wire control plug
    4. Remove + cable from alternator. Be careful not to touch ground while removing hex nut and tape the ends to prevent from making contact with ground
    5. With a 17 mm wrench and an extension, loosen serpentine belt tensioner, and release the belt from idler pulley on top
    6. Remove alternator 2 mounting bolts with 17mm socket and ratchet
    7. Pry off the alternator with a pry bar onboth sides
    8. Take it to a bench
    9. Pry off the rear plastic end cover, it just unsnaps in 4 locations. I used a small flat screw driver
    10. With an E6 torx socket, remove the regulator and brush holder screws.
    11. Remove the brush holder. I did not remove the regulator because I have the wrong regulator.
    12. The brush holder is a little tight to remove, so be patient.
    13. Inspect the slip rings. My slip rings have score marks, so i sanded it down a little, not too much.
    14. Blow all the carbon dust off the end bell
    15. Install the new brush and holder.
    16. Inspect the shaft rotation for smoothness. My bearings were still smooth and quiet, so i did not replace them.
    17. Assembled the alternator.
    14. installed the alternator back.
    15. Be careful installing the + cable back on the terminal, not to touch the ratchet to ground.
    16. Put serpentine back on, and intake snorkel.
    17. Started the engine and check charging voltage on the gauge. Confirm charging voltage with a digital meter at the battey terminal
    18. Alternator now has new carbon brushes and hoping to get another 50-100k miles.

    I decided not to replace the regulator because i have the wrong part. The bearings were smooth and quiet, so i just left them alone. The main problem were the carbon brushes. They were worn down and may loose contact with the slip rings soon and will fail to charge by then. I had to sand down the slip rings as they showed some score lines from the worn brushes.
    Hope this helps somebody who wants to tackle the same project.
    I would rate the job a 3 on as scale of 1 as easy and 10 as hard.

    Pictures attached.

    control plug.jpg old and new brushes.jpg Prying off.jpg Rear cover.jpg removing brush holder.jpg Regulator.jpg slip rings.jpg charging voltage.jpg
     
  8. KyleZ71

    KyleZ71 Rockstar 4 Years 500 Posts ROTM Winner

    great step by step break down. may do this myself sometime.

     
  9. Enkeiavalanche

    Enkeiavalanche Rockstar 4 Years ROTM Winner 5000 Posts

    :great: Very nice write up...
     
  10. The Heater

    The Heater Member 2 Years 100 Posts

    Hello, Bazar01:

    A big THANK YOU for your taking the time and making the extra effort to post not only all those steps and tools used, but to post the pictures. You have a busy life I am sure and on top of it you are doing this project, so taking time to post this is greatly appreciated by this truck and car owner. This not only gives folks the information to try to do this on their truck, but it also gives some folks the confidence that they can do it.

    Thanks again. :sign0173:
     

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