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Alternator rebuild failure

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

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amblerman
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Alternator rebuild failure

Post by amblerman » Wed Sep 11, 2019 12:22 pm

Hi Folks,

In this post I admit a failure. Not sure this post will help anyone but I wanted to discuss it.

Recently my alternator died. I asked a lot of questions about how to test an alternator but didn't get any specific answers.
I then watched a bunch of videos on youtube (to be listed below when I get a chance) that gave me enough to go on.
In the end I tested :
1) that there were no shorts in any key pieces.
2) my diodes were fine.
3) slip rings worked but were physically damaged.

In the end I tested everything except for the voltage regulator so I ordered a new one, popped that one and put it back in the car. With that done, my alternator worked. However, as noted in #3 above, my slip rings were damaged. One of the brushes had cut a significant groove in one of the slip rings so I decided to replace the slip rings.

Since I was doing that, I figured why not replace the bearings as well.

That led to several special tools (to remove alternator clutch) and WAY too many hours taking everything apart and replacing things.
Major hurdles were:
1) every phillips head screw except for two stripped out. I had to drill/tap those.
2) one of the bolts holding two halves of alternator broke. Figured out a way to get rest of threaded bolt out without having to drill it out.
3) removing front bearing required cutting bearing shell off and cracking it apart.
4) I did something stupid which damaged threads on pulley end of alternator and that took at least an hour if not more to grind off and manually repair threads with small file.
5) I really need a workshop.

But in the end, replacing bearings and slip ring was quite easy.. I tested that the slip rings were put on right (no contact with frame/core of alternator) and put everything back together.

I installed the alternator, hooked up the battery and instantly felt a wave of depression when I heard a pop and saw a small column of smoke rise up from the alternator. Started car up and sure enough, it wasn't working and idiot light on dash confirmed I messed up somehow.

I ended up ordering a Bosch alternator from FCP because I had already sunk WAY too many hours into "repairing" my alternator.
A seemingly simple (although really time consuming) job just ended in failure. I didn't really mind that I failed at this job but what really drives me nuts is I have no idea what I did wrong. I had to turn in my dead one for a core charge so I don't have the old one for any diagnosis.

The only thing I can conclude is that somehow I introduced a short in the alternator. I'm not even sure that's the right phrase. Just disappointed in not knowing what I did wrong.

Knowing what I know now, I'm not sure I'd try to rebuild an alternator again. The tools and parts cost me $70-$80 (clutch tool, bearings, slip rings, new bolts and screws, voltage regulator).. A rebuilt bosch alternator was $225.. And if I priced out my labor, I definitely spent way more than just buying an alternator.
However, I didn't do this job to save money. I wanted to learn about alternators. And that I did.. not sure what I learned thought. :-)

-A



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wizechatmgr
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Re: Alternator rebuild failure

Post by wizechatmgr » Thu Sep 12, 2019 4:36 pm

Diodes may have been okay but how was the regulator?

I've found some rebuilds for sale through the usual outlets don't necessarily work to spec...


Wisdom requires knowledge as a prerequisite, but knowledge can be developed due to a lack of wisdom.
In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD - ~183k miles

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amblerman
Posts: 254
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amblerman

Re: Alternator rebuild failure

Post by amblerman » Thu Sep 12, 2019 4:40 pm

Oh I need to clarify something.

The alternator I describe above was my own and I rebuilt it myself. The voltage regulator (Bosch), bearings, and slip rings were bought new and I replaced them in my own alternator. What I did wrong or broke is a mystery.

After my failure, I bought a Bosch rebuilt unit from FCP and it seems to be working just fine.
The frustrating thing is that although I tested everything before starting this project I did NOT test everything after. I just figured since everything worked before hand, it would work after my project. That was a big mistake as I obviously did something wrong.

-A



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