Indecisive temp gage needle

[Gregory Coe]

Well, I'm not that familiar with the older cars, honestly....

But the coolant temp sensor measures the temp of the coolant coming out of
the cylinder head, so it's most likely located at the back of the engine in
one of the hard coolant lines.  You want to change it with the car cool, so
there is no pressure in the system.  This should prevent any significant
coolant loss.  You might lose a little, but the sensor should be in the top
of the pipe, and it's one of the highest points in the system, so nothing
will come pouring out.  Typically, just unplug the connector, remove the
clip and pop out the sensor.  Swap in the new one, and you should be all
set.

This failure is very common on the A4.


> -----Original Message-----
> From: Yoder, W. douglas [mailto:yoderw at msoe.edu]
> Sent: Thursday, May 27, 2004 10:42 AM
> To: Gregory Coe
> Cc: pasquale pilato; quattro at audifans.com
> Subject: RE: Indecisive temp gage needle
>
>
> On Thu, 27 May 2004, Gregory Coe wrote:
> > Replace your coolant temperature sensor.
>
> Yeah, but which one?  I have a '87 5kcstq with the same behavior.  Aren't
> there like 3 coolant temps sensors on the type 44's?
>
> > It's a very inexpensive and easy to change part, and they are
> very failure
> > prone.  I just replaced one on my A4.  Cost about $6.00 and 5 minutes of
> > work.
>
> Well thats good to hear.  I was imagining a big mess, having to drain
> coolant, etc.  Don't you have to worry about coolant coming out when you
> take out the sensor?  Or is this one of the sensors in the upper rad.
> hose, and when the car has been sitting that hose should be empty?
>
> Please forgive my lack of experience with cooling systems.
>
> -Doug
>
> > > -----Original Message-----
> > > From: quattro-bounces at audifans.com
> > > [mailto:quattro-bounces at audifans.com]On Behalf Of pasquale pilato
> > > Sent: Thursday, May 27, 2004 8:46 AM
> > > To: quattro at audifans.com
> > > Subject: Indecisive temp gage needle
> > >
> > >
> > > Morning group,
> > > Every time I drive my 1990 100q, after several min.
> > > the needle on the temp gage starts to climb, but
> > > before it reaches its normal temp operating mark, the
> > > needle falls fast, and sits pegged on cold for the
> > > entire trip.  Most trips are less than 10 miles,
> > > Friday I'm taking it on an 80 mile trip to
> > > Indianapolis to see how it behaves then.  But I'm
> > > wondering if anyone out there experiences the same?