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Next: E34 Rear Shock Tower (129k)
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External
Since: Apr 24, 2006
Posts: 1
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(Msg. 1) Posted: Mon Apr 24, 2006 5:44 pm
Post subject: Continuing E30 Charging problems
Archived from groups: alt>autos>bmw (more info?)
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Review: Car runs until battery goes dead, when jumped starts and runs
again... for a while. Battery tests bad and is replaced, alternator tests
good. Problem remains.
Just got the alternator back in the car and got some volt readings. Before
starting battery reads 12.62v, after starting battery reads 12.3v. Same
voltage at the alternator as at the battery regardless of whether or not the
car is running. The field wire (small wire on the alternator... don't know
if that;s the proper term) read about 1v less than the battery. System
voltage slowly declines as the car runs, so it obviously isn't charging.
Now, I would still think that I'm looking at an alternator replacment, even
though it bench tested as good, as I have had that happen before, but was
wondering if there is something else in the system to check first. It's the
Bosch alternator w/ internal regulator that showed good in the testing.
Thanks to all.
Matt |
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External
Since: Jan 13, 2006
Posts: 16
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(Msg. 2) Posted: Mon Apr 24, 2006 5:44 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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The alternator should be charging the battery at over 13 volts when
running at idle, according to my experiences. Even if you load it up by
running the heated window and lights it shouldn't stray much below that
if it were healthy. I would suggest then that your alternator is
definitely no good, whether that be the diodes/regulator/something else
I wouldn't like to guess. When mine went I experienced similar issues,
and changed the whole alternator for a second hand (but known to be
good) unit and all has been well since. I should add that I also had to
replace the battery at the same time because the drain of running the
car with a bad alternator killed one of the cells, but it was at least
a few years old anyway so hopefully you won't find that necessary. |
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External
Since: Dec 22, 2005
Posts: 15
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(Msg. 3) Posted: Mon Apr 24, 2006 7:00 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Tough one. Sounds like something is different when the alternator is in the
car so it would probably be a good idea to check the ground path resistance
from the alternator to the battery. Also does the alternator light on the
dash behave normally?? It is in the current path from the battery voltage to
the field winding so if it's only dropping 1 volt with the key on and the
engine not running then it's probably not illuminated which would be
consistant with the bad ground theory. I checked the resistance on my car
(91 318is) from the alternator body to the battery ground cable end that's
just aft of the front right hand shock tower (where the battery would
normally be on an e30 318i). I got 0.3 ohms.
"RR News" wrote in message
> Review: Car runs until battery goes dead, when jumped starts and runs
> again... for a while. Battery tests bad and is replaced, alternator tests
> good. Problem remains.
>
> Just got the alternator back in the car and got some volt readings.
> Before starting battery reads 12.62v, after starting battery reads 12.3v.
> Same voltage at the alternator as at the battery regardless of whether or
> not the car is running. The field wire (small wire on the alternator...
> don't know if that;s the proper term) read about 1v less than the battery.
> System voltage slowly declines as the car runs, so it obviously isn't
> charging. Now, I would still think that I'm looking at an alternator
> replacment, even though it bench tested as good, as I have had that happen
> before, but was wondering if there is something else in the system to
> check first. It's the Bosch alternator w/ internal regulator that showed
> good in the testing. Thanks to all.
>
> Matt
> >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Jun 30, 2003
Posts: 33
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(Msg. 4) Posted: Mon Apr 24, 2006 9:46 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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RR News wrote:
> Review: Car runs until battery goes dead, when jumped starts and runs
> again... for a while. Battery tests bad and is replaced, alternator tests
> good. Problem remains.
>
> Just got the alternator back in the car and got some volt readings. Before
> starting battery reads 12.62v, after starting battery reads 12.3v.
Is that a typo? I ask because after starting, it should read about
13.2V. If not, and it's really 12.3V, there's definitely a problem with
the charging system and you have narrowed down the problem.
Ed >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Jan 17, 2007
Posts: 481
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(Msg. 5) Posted: Tue Apr 25, 2006 9:42 am
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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External
Since: Apr 25, 2006
Posts: 6
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(Msg. 6) Posted: Tue Apr 25, 2006 4:55 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Jack" wrote in message
> Tough one. Sounds like something is different when the alternator is in
the
> car so it would probably be a good idea to check the ground path
resistance
> from the alternator to the battery. Also does the alternator light on the
> dash behave normally?? It is in the current path from the battery voltage
to
> the field winding so if it's only dropping 1 volt with the key on and the
> engine not running then it's probably not illuminated which would be
> consistant with the bad ground theory. I checked the resistance on my car
> (91 318is) from the alternator body to the battery ground cable end that's
> just aft of the front right hand shock tower (where the battery would
> normally be on an e30 318i). I got 0.3 ohms.
>
I read 0.2 ohm from the alt body to that ground, which was the same reading
I get with the probes touched together.
Thanks
Matt >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Apr 25, 2006
Posts: 6
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(Msg. 7) Posted: Tue Apr 25, 2006 4:55 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Richard Sexton" wrote in message
> When you say "BOSCH alternator with an internal regulator" do you mean it
> has the plastic regulaor that bolts onto the back with two 10mm nuts?
>
Yep, that's it... though don't know about the nut size.
> If so that part is cheap and very easy to replace. It's about $18 or so.
>
But how do I know that this is the problem and not the alternator itself? I
suppose the point is that 18<200.
Thanks
Matt >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Apr 25, 2006
Posts: 6
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(Msg. 8) Posted: Tue Apr 25, 2006 4:55 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Ed Beroset" wrote in message
> RR News wrote:
> > Review: Car runs until battery goes dead, when jumped starts and runs
> > again... for a while. Battery tests bad and is replaced, alternator
tests
> > good. Problem remains.
> >
> > Just got the alternator back in the car and got some volt readings.
Before
> > starting battery reads 12.62v, after starting battery reads 12.3v.
>
> Is that a typo? I ask because after starting, it should read about
> 13.2V. If not, and it's really 12.3V, there's definitely a problem with
> the charging system and you have narrowed down the problem.
>
> Ed
Nope, no typo, the voltage was just slightly lower after starting the car
than it was off... I guess it looks like alternator replacement time...
Matt >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Jun 22, 2004
Posts: 986
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(Msg. 9) Posted: Tue Apr 25, 2006 8:55 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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In article ,
Matt Warren wrote:
> I read 0.2 ohm from the alt body to that ground, which was the same
> reading I get with the probes touched together.
Many DVMs ain't that accurate at low ohms. A better way is to measure the
voltage drop across the lead under load. Switch on headlamps and rear
window etc with the engine stopped. Should be less than about 0.2V
--
*If a parsley farmer is sued, can they garnish his wages?
Dave Plowman dave DeleteThis @davenoise.co.uk London SW
To e-mail, change noise into sound. >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Jan 17, 2007
Posts: 481
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(Msg. 10) Posted: Wed Apr 26, 2006 4:48 am
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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In article ,
Matt Warren wrote:
>
>"Richard Sexton" wrote in message
>
>> When you say "BOSCH alternator with an internal regulator" do you mean it
>> has the plastic regulaor that bolts onto the back with two 10mm nuts?
>>
>Yep, that's it... though don't know about the nut size.
>
>> If so that part is cheap and very easy to replace. It's about $18 or so.
>>
>
>But how do I know that this is the problem and not the alternator itself? I
>suppose the point is that 18<200.
You don't. But, it's stupid cheap, easy to do, the part that usually
weirds out and/or fails and you can use it on your next alternator
if it's not the problem.
Modulo some weird-ass wiring problem I'd guess this was the root of
all your evils.
--
Need Mercedes parts? http://parts.mbz.org
Richard Sexton | Mercedes stuff: http://mbz.org
1970 280SE, 72 280SE | Home pages: http://rs79.vrx.net
633CSi 250SE/C 300SD | http://aquaria.net http://killi.net >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Jan 17, 2007
Posts: 481
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(Msg. 11) Posted: Wed Apr 26, 2006 4:51 am
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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In article ,
Matt Warren wrote:
>Nope, no typo, the voltage was just slightly lower after starting the car
>than it was off... I guess it looks like alternator replacement time...
No, it's regulator replacment time. The alrternaor is just wire, magnets and
bearings, it's not screaming like a banshee or making zero volts it's just
the (cheap, easy to replace) regulator. If you have a 10mm wrench you have all the
tools and expertiase you need.
I've seen guys pay $700 for a new alternator installed at the deaeler for want
of $2 worth of brushes. Sick.
--
Need Mercedes parts? http://parts.mbz.org
Richard Sexton | Mercedes stuff: http://mbz.org
1970 280SE, 72 280SE | Home pages: http://rs79.vrx.net
633CSi 250SE/C 300SD | http://aquaria.net http://killi.net >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Apr 25, 2006
Posts: 6
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(Msg. 12) Posted: Wed Apr 26, 2006 8:55 am
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Richard Sexton" wrote in message
> In article ,
> Matt Warren wrote:
> >Nope, no typo, the voltage was just slightly lower after starting the car
> >than it was off... I guess it looks like alternator replacement time...
>
> No, it's regulator replacment time. The alrternaor is just wire, magnets
and
> bearings, it's not screaming like a banshee or making zero volts it's just
> the (cheap, easy to replace) regulator. If you have a 10mm wrench you have
all the
> tools and expertiase you need.
>
> I've seen guys pay $700 for a new alternator installed at the deaeler for
want
> of $2 worth of brushes. Sick.
>
True enough, I'll start with that little gem. Thanks
Matt >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Dec 22, 2005
Posts: 15
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(Msg. 13) Posted: Wed Apr 26, 2006 8:55 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Let us know how it turns out, Matt. I'm still wondering why your alternator
tests OK out of the car but doesn't work when it's installed.
"Matt Warren" wrote in message
>
> "Richard Sexton" wrote in message
>
>> In article ,
>> Matt Warren wrote:
>> >Nope, no typo, the voltage was just slightly lower after starting the
>> >car
>> >than it was off... I guess it looks like alternator replacement time...
>>
>> No, it's regulator replacment time. The alrternaor is just wire, magnets
> and
>> bearings, it's not screaming like a banshee or making zero volts it's
>> just
>> the (cheap, easy to replace) regulator. If you have a 10mm wrench you
>> have
> all the
>> tools and expertiase you need.
>>
>> I've seen guys pay $700 for a new alternator installed at the deaeler for
> want
>> of $2 worth of brushes. Sick.
>>
>
> True enough, I'll start with that little gem. Thanks
>
> Matt
>
> >> Stay informed about: Continuing E30 Charging problems |
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External
Since: Apr 25, 2006
Posts: 6
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(Msg. 14) Posted: Thu Apr 27, 2006 9:55 pm
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
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External
Since: Jun 22, 2004
Posts: 986
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(Msg. 15) Posted: Fri Apr 28, 2006 6:55 am
Post subject: Re: Continuing E30 Charging problems [Login to view extended thread Info.]
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In article ,
Jack wrote:
> Let us know how it turns out, Matt. I'm still wondering why your
> alternator tests OK out of the car but doesn't work when it's installed.
It's a strange way to test. The alternator may be checked for output with
a DVM without being removed. Voltage drop tests between it and battery on
both positive and ground should also be carried out on the car. As should
a quiescent current test to show up a failed diode, etc. The only thing
that can't be done is a maximum output test. But you can nearly by
switching everything on and making sure it is still charging.
--
*No hand signals. Driver on Viagra*
Dave Plowman dave RemoveThis @davenoise.co.uk London SW
To e-mail, change noise into sound. >> Stay informed about: Continuing E30 Charging problems |
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