Bizzare Starter Motor Problem

Scroll down for diagnosis. Textbooks and FSM of no value.

Symptom: This is an intermittant starter malfunction. Most of the time,
when the key is turned to "start" the engine cranks normally. Sometimes,
however, there is a momentary delay before starter engagement. During this
delay, there is no sound from the starter or solenoid. The delay can range
from a fraction of a second to several seconds, but the engine always
cranks. Sometimes it helps when the key is switched several times. When
the key is in the start position, the engine warning light illuminates and
the dash voltmeter dips. The engine is an inline four, turbocharged, fwd
configuration. What caused this odd fail to crank difficulty? Answer
below.
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The starter motor heat shield. The heat shield is a composite of
insulation fiber with a heavy foil relector. When the shield deteriorated,
the foil came into contact and shorted the relay-actuated solenoid power
input terminal. When the switch goes to start, the solenoid terminal is
partially or fully grounded, depending on the corroded foil surface
condition. The unfused solenoid power input would arc or melt a hole in
the foil, at which time enough current would feed into the solenoid to
actuate it and close the starter motor contacts. From engine operation,
the loosened foil would move about, sometimes shorting the terminal and at
other times, not, causing a difficult-to-diagnose problem. When the
problem was resolved, the foil was full of burned spots and holes. The
starter and terminals are not readily visible for mechanic's inspection or
attachment of multi-tester leads in this model, making the intermittant
even harder to find.

 

On Wed, 29 Mar 2006 02:20:05 +0200, Nomen Nescio wrote:

TOP POST

Sounds like a fire hazard to me...

shakiro

 

There is a set of copper contacts in the starter. Then you engage the
starter solenoid by turning the key, these contacts slam into each
other while one of them is turning. Over time these parts wear and
pit. Eventually, they become so worn down that they do not always make
contact, or may not make contact right away.

Look around your local area. I found a place near me that rebuilds
starters and alternators. They do NOT do re&re. So if you take the
starter out and give it to them, they will take it apart and fix it. I
had a mobile mechanic to the re & re for, IIRC, $30. They pulled apart
the starter. Sure enough, copper contacts - 35 cents. And about $40
labour to machine one of the internal parts smooth again, and
re-assemble the starter. So total cost was about $80 parts, labour,
taxes. oh, and a one year warranty. Not too shabby.

And, since I got it done before the starter totally died, I was never
left stuck somewhere (saved a tow charge!

hth

 

did you actually read his post?