These thermostats with a hole were common 20 years ago but I have not seen
them since. It seems the better German ones had the holes. I know of a shop
that still drills Vanagon thermostats, their stance is that the hole helps
pre-warm the cold coolant on the other side of the thermostat and prevents
air bubbles in the system by equalizing pressure on both sides of the
closed thermostat. I personally see no need to drill them or to go out of
my way to find drilled ones.

Jim

On Fri, Apr 23, 2021 at 11:42 AM Dan N <dn92610@gmail.com> wrote:

> thank you Dennis,
>
> I think the thermostat in there doesn't open fully. When the engine is
> warm, usually the coolant temp. needle sits on the bottom side of the red
> LED, now it sits a bit higher on the other top side of the red LED. When I
> open the heater at full the temp. needle doesn't move down at all. It's
> working, no overheat but I feel that something wrong/lazy with the
> thermostat. I could be wrong but I don't feel comfortable with what I see.
>
> dan
>
>
> On Fri, Apr 23, 2021 at 9:25 AM Dennis Haynes <d23haynes57@hotmail.com>
> wrote:
>
> > What problem are you trying to fix? As the Vanagon cooling system has so
> > much reserve capacity especially during cold weather getting the engine
> up
> > to temperature is actually a concern. The latest OEM thermostat,
> revision F
> > not only does not have a bypass, the top throttle plate is actually
> > gasketed to prevent any bypass from the radiator until it actually moves
> to
> > open. With a good stat this begins around the 87C. If you really want a
> > bypass open the bleed valve at the top of the t-stat housing.
> >
> > Dennis
> >
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List <vanagon@gerry.vanagon.com> On Behalf Of Dan
> N
> > Sent: Friday, April 23, 2021 12:07 PM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Thermostat with a hole?
> >
> > hi all,
> >
> > I am planning to replace the thermostat on my tintop syncro 2.1 WBX. I
> > will get an 80° thermostat.
> >
> > When researching the topic on thermostats I found that some of them have
> a
> > tiny hole on it (about 1/16" diam.) and some of them don't have.
> >
> > Is there a pro and con idea of having one with the 1/16" hole - or even
> > drill one hole?
> >
> > thanks for your help,
> >
> > dan
> >
>