Re: TC Running Temp
Posted: Mon May 22, 2017 8:58 am
Chancer wrote:You are right Andy, the advantage is that (at S.T.& P.) water will boil at exactly 100?c, infra red temp guns (I have a couple) are great as comparators but the indicated value will change according to the surface finish of the item, its not the best way to measure coolant temp.
I have a problem on my Skoda, the guage which was always rock steady at 90?c now sits at 80?c and sometimes goes up a bit, used a 330 ohm resistor and got the half scale deflection so guage OK, IR temp gun inconclusive, its either the sender (been replaced once for fast idle problem) or the stat sticking open a bit, tested stat in pan of boiling water, it opens fully but inconclusive regarding 80 or 90? so I will soon be putting the sender in a bioling kettle and will know for sure what to replace.
I presume your Skoda is a VW based car?
The 'rock steady at 90C' is actually only vaguely related to coolant temperature. Well not vague as such but the value displayed on the gauge is not direct from the sensor but is modified by the software in order to present a comforting feeling to the driver. The VW gauge is an improvement on just having an over-temperature warning light on the dashboard as it will indicate both high and low temperature but it is a very non linear measuring system. VW (and other motor manufacturers I imagine) arrange the gauge reading so that as long as the coolant is within a temperature band that they consider acceptable for running conditions, will show the 90 degree mid scale value. The driver does not really need to know if the engine is at 84.2 or 91.3 degrees, the driver just needs to know there are no problems.
So, if your gauge is not showing 90 I suspect the engine is not running at the temperature its supposed to.
Ian