On Sat, Jul 5, 2008 at 12:55 PM, Mike S <mikes@flatsurface.com> wrote:
> At 03:18 PM 7/5/2008, neil N wrote...
>>
>> Hi all.
>
> Hi Neil.
>
>> Does the voltage stabilizer work in conjunction with the engine
>> coolant temp gauge?
>
> Yes, it provides a constant 10 volts for the gauges.
>
>> i.e. if one took the engine temp gauge out of the cluster, connected
>> it straight to the temp sending unit (sensor) and 12+, would this give
>> an innacurate reading of engine coolant temp?
>
> Yes.
>
>> Like maybe too high?
>
> Yes.

Thanks Mike. This may explain why the needle on the Jetta coolant
gauge pinned all the way to the right when I hooked it up to my
VanaJetta conversion (this was done after some test runs up some
mountain hills)

> The gauges are bimetallic - they work by heating a special piece of metal
> which bends as it gets warm. There's a heating coil wrapped around tha piece
> of metal. 10 volts from the regulator goes to one end of the heating coil,
> the other is connected to the sensor (fuel, temp). The sensors offer a
> variable resistance. Less resistance causes more current to flow, making
> more heat, bending the metal more, making the gauge read higher.
>
> If you bypass the regulator, then you have 12 volts on one end of the
> heater, so more current will flow than is intended, and the gauge will read
> higher than it should.
>

I appreciate the insights into the workings of the gauge etc. I
actually popped it open to see of there wasn't something obviously
wrong with it. Turns out I had it wired wrong.

Good to know that my engine may not be totally overheating!

Cheers,

Neil.