kevtherev wrote:California Dreamin wrote:Hi Kev,
I can see why you would think that from the Haynes description 'As the temperature of the coolant rises the thermostat opens, allowing partial and then full circulation of the coolant through the radiator'
But what the Haynes describes is a point at which the cold coolant from the radiator mixes with the hot coolant from the engine and the opening and closing action of the thermostat until all the coolant reaches the thermostat 'pre-set' temperature at which point the thermostat stays open.
Having discussed this with two of my collegues we all agree that you may be thinking about old fashioned bellows or alcholol filled thermostats which were 'linear' and do indeed progressively open (the hotter the coolant the wider open they get)
Those particular types have long since been replaced by the waxstat which doesn't open progressively but opens fully as soon as it reaches it's pre-determined temperature.
To explain this I'll quote directly from the Hillier's book 'The wax type element depends for it's operation upon the considerable change in volume which occurs in certain types of wax at around melting point in laymans terms: when the wax within the capsule melts from a solid to a liquid it rapidly expands pushing the pin outwards opening the thermostat...this isn't a progressive action just the difference in volume of the wax between it being a solid or liquid.
Martin
All well and good if it was a "waxstat" type... but... it's not.
It's a bi-metal spring type, you can open them with your hands even when cold, I doubt you can do that with wax, as you say, that's solid.
I'm sure that my schoolboy physics is still correct with bi metal strips and springs being progressive with temperature.
I also think dumping the contents of a cold radiator into a hot engine sounds really wrong.. hence the gradual cooling from a lower temp as indicated by the Haynes.
Kev...now you are confusing me, you are talking about a thermostat like the one fitted to markbikerider's 1987 2.1 wasserboxer?
like this one on Simons site?:
http://www.brickwerks.co.uk/shop?page=s ... lypage.tpl" onclick="window.open(this.href);return false;
Certaily looks like a waxstat to me......
Pretty much every water cooled car engine dating back to the 70's has a waxstat fitted, I'm sure there are acceptions but I can't think of any.
As for 'dumping the contents of cold radiator into a hot engine, it doesn't! the thermostat opens and closes as many times as it takes, letting a little cold water in, shutting as the wax re-sets, heating up again, opening, letting a little more cold water through until all the coolant surrounding the stat is above it's pre-set at which point it stays open.
Some Peugeot's and Renaults had dual temperature waxstats fitted, effectively opening in two stages but still not progressive.
Of course your schoolboy physics is correct and bi metal strips and springs are progressive with temperature but thermostats fitted to watercooled T25's have always been waxstats, as shown on the Brickwerks link..
Martin
) I know there is supposed to be heat , what the exhaust and everything being back there too, but would like to know what your experiences are...?
it may well get hotter after this happens...
