[Vwdiesel] temp gage

[mikitka]

Makes sense to me.
Nick
 


At 06:26 PM 10/17/05 -0400, you wrote:
>I was wondering why my temp gage reads slightly higher when driving at
night
>with the lights on. During the hot summer days it runs just barely touching
>the center line on the gage but when I drive into work in the morning or
>coming home in the dark the needle runs straight up on the center line.
>This morning really got me because it was our coldest this year at 45 F/
7.2
>C and it ran the same slightly higher in temp and I even was running the
>heater inside the car. Could it be due to the difference in the electrical
>voltage due to the draw of the headlights being on putting more of a load
on
>the alternator? Or even the extra heat in the dash from the dash lights????
>Just seems odd to have two different readings.


This common phenomenon has been noted by others on the forum, as I learned
after asking the same question last year.

Manifested as guage showing lower temps in hot weather, and higher in
winter.

In summer, the hot coolant from the end of the head passes through the
heater core, where it does not lose any heat, because you have the heater
door closed for cool air. This allows coolant to return to the waterpump
without any significant cooling, where it hits the thermostat element
directly, causing it to open a little further, resulting in lower head
temperature.

In winter, with the heater going full blast, the returning coolant is cooler
when it gets to the thermostat, causing it to close a bit, resulting in
higher head temperature.

I would find it difficult to believe the volks engineers did this with
intent, rather, the return from the heater fortuitously impinges directly on
the thermostat control element, giving you a little more heat in winter when
you need it.

Sandy
My rational on it is,