Queuing to drive into Stratford-upon-Avon, this morning, I noticed that my temperature gauge started climbing a little (as you would expect) -- although the fan switched on, as it should, and brought it back down: but not quite to the halfway mark, until I started moving again. So, being the nerd I am, I wondered how this related to actual coolant temperatures....
I have one of these permanently plugged into my Punto's OBD socket: so switched the app on my iPhone onto live data -- and this is what I found...
Hopefully, this is of interest to someone other than me.... :nutter:
I have one of these permanently plugged into my Punto's OBD socket: so switched the app on my iPhone onto live data -- and this is what I found...
- According to the owner handbook, the gauge starts to move once the coolant reaches 50°C. I couldn't test this, as my engine was already warm.
- Normally -- e.g. when you're travelling at between 30-50 mph (even in today's 25°C temperatures); and when the gauge is rock steady at the halfway point -- the coolant temperature is between 85 and 89°C (and usually at 87°C): which concurs with the thermostat specs in the Haynes manual.
- If the temperature rises -- e.g. because you're stationary, or moving slowly -- the temperature gauge will still stay at the halfway mark until 100°C.
- Once it starts crawling upwards, it's out of all proportion to the actual temperature: e.g. at three-quarters (which is the maximum it reached), it was only 103°C. However, if the coolant is going to boil, it's not going to be actually doing any cooling. [According to Wikipedia: "With proper antifreeze (sic), a wide temperature range can be tolerated by the engine coolant, such as -37°C to 129°C for 50% (by volume) propylene glycol diluted with water and a 15 psi pressurized coolant system."]
- I can't find a maximum figure -- or specification -- for when the temperature warning light comes on: but my belief has always been that this is actually a 'head gasket replacement light'; and that, once it lights up, you're frelled.... [If someone actually has a maximum figure, to complete the picture, I would be extremely grateful.]
Hopefully, this is of interest to someone other than me.... :nutter: