Well heres what I have found about thermostats.
If your dealer sells after market parts, you may find that
the thermostat don't fit your syncro. Once again the housing
is different. Knowing that the original thermstat works in
both, you would think it is safe to going into the dealer
and request a thermostat for any old 2.1 engine. Not the
dealer in Pgh. (at the time Ted Mcwilliams) This is where
the problem is. The after market stats have bigger discs
on the bottom.  What it does to the operation is another
question. ....

            Eric                   86-VW4x4
            vw4x4@fyi.net          72-240z
            Pittsburgh, PA USA     1936-Chrysler

On Sun, 5 Apr 1998, Mark McCulley wrote:

> At 12:05 AM 4/6/98 -0400, EMZ wrote:
> >On Fri, 3 Apr 1998, Mark McCulley wrote:
> >
> >> At 03:44 PM 4/2/98 -0800, Sam Scholten wrote:
> >> >If that is your problem, check out the archives for info on Syncro
> >> >thermostats- they're different. If that isn't the problem, check the
> >> >radiator fan motor.
> >> >
> >> Are syncro thermostats really different? Why?
> >>
> >> -Mark McCulley
> >>
> >  Yes they are. Does it make much difference I don't think so.
> >The difference is the disc on the very bottom. For some reason
> >in the Syncro, VW used an Aluminum thermostat housing and
> >changed the hole that this disc covers.
> Can you get us the part numbers of the the syncro thermostat and the
> non-syncro thermostat? That would be very helpful.
>
> Thanks,
> Mark McCulley
>
>