Starter Problems?

[Bernie Benz]

> From: "Derek Pulvino" <dbpulvino at hotmail.com>
> 
> Well, yesterday got the voltmeter out and I do have 12v at both the main
> power in to the solenoid and the trigger wire from the key (when it's
> turned).  I did also find that the insulation on the trigger wire is
> absolutely destroyed on the last 4-inches or so of the wire.  I haven't
> checked resistance on those components or on that jumper wire.
> 
> So, after finding the above pulled the starter out and had it bench tested;
> it turns over fine, but I wonder if a load condition would effect the
> actuall output...ie if it had been bench tested under load if the motor
> still would have turned.
> 
> The other question I had is if volts is really the right measurement.
> Wouldn't corroded wires restrict the current flow?  Is that were looking for
> voltage drop under load vs unloaded comes in?
Now you're getting close to asking the right Qs, Derek.  Resistance or open
circuit voltage is all but meaningless in this instance.  Hook the voltmeter
to the power lead at the starter contactor input terminal and measure the
voltage drop, no load vs. starting load.  Should be only a few volts
difference.  Do the same at the terminal into the starter from the
contactor.  By this method you can isolate where the load current losses
are.  Could be the battery to, do the same at the bat terminals, and the bat
ground return.

Bernie

> 
> Derek P
> 
>> At 04:47 PM 12/11/2005, Derek Pulvino wrote:
>>> Now that I have some light, I'll be checking those things today.  Reading
>>> at Blau, I also saw that there's a large gauge jumper wire that runs from
>>> the solenoid to the starter motor that can also be suspect.
>>> 
>>> I'll post back with my findings.
>>> 
>>> Derek P
>>> 
>>>> I'd start by checking out the wiring at the starter itself.  There's the
>>>> big wire that carries power to operate the starter and there's the little
>>>> wire that comes from the switch to tell the starter to start operating.
>>>> The former can have corroded contacts and the latter can deteriorate
>>>> internally because Audi seems to use starter wires whose insulation isn't
>>>> very good considering the environment it works in.
>> 
>> 
>> Derek:
>> Large gauge wire from Solenoid to starter is what carries the power to the
>> motor brushes.
>> 
>> For some unknown reason Bosch saw fit to NOT insulate the wire, even though
>> it carries ALOT of current.
>> 
>> It is also the major weak spot on the starter.
>> 
>> Use an ohmeter and check for any resistance between the post on the
>> solenoid where it attaches ( 10 or 13MM nut) and what appears to be the
>> starter body ( is actually insulated area for the motor brushes) .
>> 
>> If you are lucky it might just be some corrosion on the post on the starter
>> side.
>> 
>> If not you will either have to replace the lead (with one from another
>> starter), have the starter rebuilt locally, or a replacement starter.
>> 
>> HTH
>> 
>> -Peter
>> 
>> 1991 200 20v Q Avant Titan Grey
>> 1991 200 20v Q Avant Indigo Mica
>> 1991 90 20v Q Red
>> 1990 CQ silver (awaiting S2 engine transplant)
>> 
>> 1990 CQ red ( to part or not)
>> Chelmsford Ma, USA
>> 
> 
> 
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