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Originally Posted by engineered
Since this has been revived, why not use a 12V block heater and/or 12V oil pan heater to heat up the fluids? They could be used manually or controlled automatically to come on with the car and turn off at a certain coolant temp (or from the tstat).
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The purpose of this thread is to use 'free' exhaust heat to speed up the warming of the engine to decrease fuel consumption.
A block heater does work, if you have 110V power. If you don't, this device can and will help.
Using 12V power from the alternator will actually increase fuel consumption, not decrease it. So that kind of defeats the purpose we are going for at least, though you would get heat quicker. VW actually does do this with their TDI engines to get them up to temperature faster.
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How would coolant water (and glycol) degrade? It doesn't break down like motor oil. I'm mean if you overheat it, it would eventually vaporize, but 98'C water is always going to be the same water.
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Vman is correct. Ethlyene glycol is only supposed to be
good to 250F / 121C. It will start cracking at around 285F / 140C according to
this paper (page 16). That is certainly achievable by warming the coolant with the exhaust. I'm not sure if the water will start boiling out before that point or not, but if it does, thats not good either.