Cylinder head water manifold (early)

[David.H]

In that case I reckon a new gasket sounds like a good idea. I feel sure Jamie at Seven Workshop or one of our other stalwart suppliers can provide. Yes, go easy on the joint at least until you can see how strong it is (and even then...)

You are absolutely right, glycol antifreeze does raise the BP of water (though not as much as it lowers freezing point). However it has a lower specific heat capacity (meaning it takes less energy to raise its temperature) and higher viscosity (meaning it flows less freely) than water (how much of course depends on the dilution). Cooling systems designed for ethylene glycol coolant have to be significantly bigger in capacity to achieve the same result as plain water, which is a surprisingly good coolant. Surface tension may be an issue too - hence 'water wetters' which seek to disperse the film of bubbles which form on the surface to be cooled, which tend to inhibit heat transfer. I guess the imperative in aircraft systems is to prevent freezing at high altitude, where temperatures can be pretty brassy.

Anti-corrosion properties are of course another question, and it's a good idea to have something in your system. Anyway, I digress - there are plenty of A7 owners driving around using glycol antifreeze and there's nothing to worry about as long as your car is not overheating.

Thank you...clearer now! bigger problem is the carb overflowing!
D