[ba] 89 90 hot-start problem. [VERY odd]

Buchholz, Steven Steven.Buchholz at kla-tencor.com
Tue Jul 9 19:33:05 EDT 2002

... this is a very common malady on older Audis ... I've lived through it on
my '78 Fox and the urq ...

It is likely to be a combination of aging components ... the resistance in
the switch on the steering column is increased, the resistance in the wires
from the key to the starter solenoid has increased ... and the starter has
aged and is more difficult to get to pull in.  Over and above this, your
ground cable from the engine block to the body of the car may be
deteriorated.  All this leads to a situation where the electrical system
cannot provide enough oomph to get the solenoid to pull in ... and if the
solenoid won't pull in you won't hear any clicks or action in the starter.
VW actually has a TSB on this ... what you do is to measure the voltage at
the starter solenoid terminal to the engine block ... if that voltage is
less than 9.6 volts they give a drawing of a relay you can add to give a
better voltage supply to the starter.  I'm pretty sure Bentley has a check
for the voltage as well, but they don't tell you what to do if the voltage
is low.

Adding a relay is a pretty simple matter, and it would likely give you a car
that started more reliably ... but really the underlying problem is that
your starter is wearing out ... and you will need to replace it somewhere in
the near future anyway.  From my experience swapping the starter cures the
hot start problem ...

Steve Buchholz
San Jose, CA (USA)
> im wondering if theres easy places to look for this very
> intermittent +
> weird issue with my new/old 90...
> twice now my 90 has failed to hot-start after driving on hot
> days [95ish]
> with the ac on. it runs GREAT, the 1st time for 4 or 5 hours,
> i shut it off,
> come back 15-20 minutes later, and i get nothing on turning
> the key. no
> clicks, nada. all lights come on fine, car has plenty of juice.
> wait 5 minutes or so and it starts. ????? battery/electrical
> seems fine, car
> never runs hot.
> is there some sort of temp related switch that will prevent
> the car from
> starting if its too warm? will starters just NOT engage like
> that  if theyre
> too hot? it doesnt exhibit ANY other symptoms..

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