Repairing alternator

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Old 25 Oct 2003, 08:28 pm   #1 (permalink)
MM
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Default Repairing alternator

Hi all,

I am trying to repair an alternator for 6cyl Camry'89. When tested by a shop
it produced 11V as they told me. I disassembled it and checked the stator
continuity, the continuity between the rotor slip rings, and the diodes. All
these seem OK. I couldn't get the rotor out, so I haven't checked for shorts
there and I don't know how to check the voltage regulator. The brushes seem
a little short but I think they are OK. The only problem I could spot is
that one of the rotor slip rings has an angled groove and the corresponding
brush doesn't seem to be angled that way...

Does anyone have experience to tell me what most likely my problem is?

Thanks,
/Mikhail



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Old 25 Oct 2003, 09:44 pm   #2 (permalink)
Philip ®
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Default Re: Repairing alternator

In news:bnf80b$10kv1k$1@ID-204311.news.uni-berlin.de,
MM <mbmsv@yahoo.com> being of bellicose mind posted:
> Hi all,
>
> I am trying to repair an alternator for 6cyl Camry'89. When tested
> by a shop it produced 11V as they told me. I disassembled it and
> checked the stator continuity, the continuity between the rotor
> slip rings, and the diodes. All these seem OK. I couldn't get the
> rotor out, so I haven't checked for shorts there and I don't know
> how to check the voltage regulator. The brushes seem a little
> short but I think they are OK. The only problem I could spot is
> that one of the rotor slip rings has an angled groove and the
> corresponding brush doesn't seem to be angled that way...
>
> Does anyone have experience to tell me what most likely my problem
> is?
>
> Thanks,
> /Mikhail


Disassemble your alternator and rerun your tests. Brushes worn close
to the "dot" are done. Also, both the stator and rotor must have a
few ohms resistance. Not too much, and certainly not zero. Same
with stator.


--

~~Philip "Never let school interfere
with your education - Mark Twain"




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Old 25 Oct 2003, 10:18 pm   #3 (permalink)
MM
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Default Re: Repairing alternator

Hi Philip,

Thanks for responding.

> Disassemble your alternator and rerun your tests. Brushes worn close
> to the "dot" are done.


That "dot" you refer to, is it a little round cavity on the side of the
brush? If it is, there is a little less than half of it left... however the
Haynes manual says that the brushes can go as low as 0.06" albeit it is hard
to believe they will reach the rotor when so short...

Related question:
Do Toyota dealerships sell things like brushes for alternators or should I
go somehwere else to get them?

/Mikhail


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Old 25 Oct 2003, 10:35 pm   #4 (permalink)
Philip ®
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Default Re: Repairing alternator


"MM" <mbmsv@yahoo.com> wrote in message
news:bnfedh$10cj12$1@ID-204311.news.uni-berlin.de...
> Hi Philip,
>
> Thanks for responding.
>
> > Disassemble your alternator and rerun your tests. Brushes worn

close
> > to the "dot" are done.

>
> That "dot" you refer to, is it a little round cavity on the side of

the
> brush? If it is, there is a little less than half of it left...

however the
> Haynes manual says that the brushes can go as low as 0.06" albeit

it is hard
> to believe they will reach the rotor when so short...
>
> Related question:
> Do Toyota dealerships sell things like brushes for alternators or

should I
> go somehwere else to get them?
>
> /Mikhail



BINGO!!!! Replace the brush set/holder. Dealer item for about
$20. Don't both trying to repair it.


--

~~Philip "Never let school interfere
with your education - Mark Twain"




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Old 25 Oct 2003, 11:06 pm   #5 (permalink)
Steve Sr.
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Default Re: Repairing alternator

While you're at it you should probably also replace the bearings as
they probably have about 150K miles on them. Any auto electric shop
could do this inexpensively. Saves removing the pully and pulling or
pressing the front bearing.

Steve



On Sat, 25 Oct 2003 21:28:52 -0400, "MM" <mbmsv@yahoo.com> wrote:

>Hi all,
>
>I am trying to repair an alternator for 6cyl Camry'89. When tested by a shop
>it produced 11V as they told me. I disassembled it and checked the stator
>continuity, the continuity between the rotor slip rings, and the diodes. All
>these seem OK. I couldn't get the rotor out, so I haven't checked for shorts
>there and I don't know how to check the voltage regulator. The brushes seem
>a little short but I think they are OK. The only problem I could spot is
>that one of the rotor slip rings has an angled groove and the corresponding
>brush doesn't seem to be angled that way...
>
>Does anyone have experience to tell me what most likely my problem is?
>
>Thanks,
>/Mikhail
>
>


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Old 25 Oct 2003, 11:59 pm   #6 (permalink)
John
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Default Re: Repairing alternator

If it is producing 11 volts it is probably faulty in the regulator or the
primary circuit. I would make sure the brushes are contacting the slip rings
and that there is continuity through the slip rings to the winding. If all
seems ok there then investigate the regulator. You may be able to bypass the
regulator and see if the output increases.

--

John
"MM" <mbmsv@yahoo.com> wrote in message
news:bnf80b$10kv1k$1@ID-204311.news.uni-berlin.de...
> Hi all,
>
> I am trying to repair an alternator for 6cyl Camry'89. When tested by a

shop
> it produced 11V as they told me. I disassembled it and checked the stator
> continuity, the continuity between the rotor slip rings, and the diodes.

All
> these seem OK. I couldn't get the rotor out, so I haven't checked for

shorts
> there and I don't know how to check the voltage regulator. The brushes

seem
> a little short but I think they are OK. The only problem I could spot is
> that one of the rotor slip rings has an angled groove and the

corresponding
> brush doesn't seem to be angled that way...
>
> Does anyone have experience to tell me what most likely my problem is?
>
> Thanks,
> /Mikhail
>
>
>



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Old 26 Oct 2003, 01:47 am   #7 (permalink)
MDT Tech®
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Default Re: Repairing alternator

MM wrote:

> Hi all,
>
> I am trying to repair an alternator for 6cyl Camry'89. When tested by a shop
> it produced 11V as they told me. I disassembled it and checked the stator
> continuity, the continuity between the rotor slip rings, and the diodes. All
> these seem OK. I couldn't get the rotor out, so I haven't checked for shorts
> there and I don't know how to check the voltage regulator. The brushes seem
> a little short but I think they are OK. The only problem I could spot is
> that one of the rotor slip rings has an angled groove and the corresponding
> brush doesn't seem to be angled that way...
>
> Does anyone have experience to tell me what most likely my problem is?
>
> Thanks,
> /Mikhail
>
>
>

Replace the brushes

--




Terrorist, kill them, its cheaper than trying to get them to like you!

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Old 26 Oct 2003, 02:25 pm   #8 (permalink)
Evil Homer
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Default Re: Repairing alternator

On all alternators I have worked on, (although I have not worked on a Toyota
alternator), there is a way to bypass the regulator and apply full power to
the fields. If you do this and the voltage goes up (ie. varies with the
speed of the alternator without ever being regulated to 13.8v) then it is
almost certain that the regulator is shot. The regulator is my best guess,
and while you're at it I would replace teh brushses. They're not that
expensive, and it saves you from going back in later to replace the brushes.


"MM" <mbmsv@yahoo.com> wrote in message
news:bnf80b$10kv1k$1@ID-204311.news.uni-berlin.de...
> Hi all,
>
> I am trying to repair an alternator for 6cyl Camry'89. When tested by a

shop
> it produced 11V as they told me. I disassembled it and checked the stator
> continuity, the continuity between the rotor slip rings, and the diodes.

All
> these seem OK. I couldn't get the rotor out, so I haven't checked for

shorts
> there and I don't know how to check the voltage regulator. The brushes

seem
> a little short but I think they are OK. The only problem I could spot is
> that one of the rotor slip rings has an angled groove and the

corresponding
> brush doesn't seem to be angled that way...
>
> Does anyone have experience to tell me what most likely my problem is?
>
> Thanks,
> /Mikhail
>
>
>



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Old 26 Oct 2003, 06:04 pm   #9 (permalink)
Philip ®
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Default Re: Repairing alternator

Evil.... you need to familiarize yourself with Nippon Denso
alternators. Hot circuiting any alternator rotor when the brushes
are shot will give you a false failed regulator diagnosis.
Furthermore, when brushes are barely contacting either slip ring, a
continuity test of the rotor via the brushes may show good on the
bench but go open (or increased resistance) with the rotor in
operation. Result is marginalized output.
--

~~Philip "Never let school interfere
with your education - Mark Twain"

>In news:1067199919.196474@news,
>Evil Homer <imnot@home.com> being of bellicose mind posted:
> On all alternators I have worked on, (although I have not worked
> on a Toyota alternator), there is a way to bypass the regulator
> and apply full power to the fields. If you do this and the voltage
> goes up (ie. varies with the speed of the alternator without ever
> being regulated to 13.8v) then it is almost certain that the
> regulator is shot. The regulator is my best guess, and while
> you're at it I would replace teh brushses. They're not that
> expensive, and it saves you from going back in later to replace
> the brushes.
>
>
> "MM" <mbmsv@yahoo.com> wrote in message
> news:bnf80b$10kv1k$1@ID-204311.news.uni-berlin.de...
> > Hi all,
> >
> > I am trying to repair an alternator for 6cyl Camry'89. When
> > tested by a shop it produced 11V as they told me. I disassembled
> > it and checked the stator continuity, the continuity between the
> > rotor slip rings, and the diodes. All these seem OK. I couldn't
> > get the rotor out, so I haven't checked for shorts there and I
> > don't know how to check the voltage regulator. The brushes seem
> > a little short but I think they are OK. The only problem I could
> > spot is that one of the rotor slip rings has an angled groove
> > and the corresponding brush doesn't seem to be angled that
> > way...
> >
> > Does anyone have experience to tell me what most likely my
> > problem is?
> >
> > Thanks,
> > /Mikhail




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Old 27 Oct 2003, 08:38 am   #10 (permalink)
Speedy
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Default Re: Repairing alternator

X-No-Archive: yes

MM wrote:
> Hi all,
>
> I am trying to repair an alternator for 6cyl Camry'89. When tested by a shop
> it produced 11V as they told me. I disassembled it and checked the stator
> continuity, the continuity between the rotor slip rings, and the diodes. All
> these seem OK. I couldn't get the rotor out, so I haven't checked for shorts
> there and I don't know how to check the voltage regulator. The brushes seem
> a little short but I think they are OK. The only problem I could spot is
> that one of the rotor slip rings has an angled groove and the corresponding
> brush doesn't seem to be angled that way...
>
> Does anyone have experience to tell me what most likely my problem is?
>
> Thanks,
> /Mikhail
>


Use it as a core at Pep Boys for a new alternator and get their lifetime
guarantee alternator. I've done that and got 3 alternators for the
price of one so far in the long history of my 1985 2wd Toyota Truck!


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