[Healeys] Head Gasket

[Michael Salter]

Interesting article Bob but IMHO their statement:
"Pressure in a cooling system is vital for keeping water in contact with the
metal surfaces of the cylinder heads and block."
is something of an over simplification.
The reality is that any "boiling " of the coolant produces a "bubble" of
gaseous coolant, there is no air, as such, involved.
Their statement :
"Pressure keeps the air compressed and maintains the water-to-metal
contact. "
suggests that the cooling system contains air; it shouldn't contain any
air, other perhaps the very small quantity disolved in the coolant.
Pressurizing the cooling system raises the boiling point. Raising the
boiling point means that the temperature of the engine surfaces where
gaseous coolant will be generated will also  need to be higher for boiling
to occur.
As the rate of heat radiation from the cooling surfaces is proportional to
the 4th power of the absolute temperature there is also a considerable
increase in the amount of energy that can be dissipated by the radiator.
These things together make pressuring the cooling system even to only 7
p.s.i. very advantageous.
As I mentioned earlier the problem with the 100 insofar as cooling system
pressure is concerned is the carbon seal in the water pump and perhaps the
design of the radiator tanks.

M



On Thu., Feb. 24, 2022, 10:42 a.m. Bob Spidell, <bspidell at comcast.net>
wrote:

> I was about to jump in and say "But, but, but .... pressure only raises
> the boiling point but, for once, I did some 'research' first:'
>
> "Pressure in a cooling system is vital for keeping water in contact with
> the metal surfaces of the cylinder heads and block."
>
>
> https://www.motortrend.com/how-to/understanding-the-cooling-system-cool-under-pressure/
>
>
> On 2/24/2022 7:01 AM, john harper via Healeys wrote:
> > Alan
> >
> > Many A90 Atlantics suffered overheating. The club developed a fairly
> > simple adapter that screwed in place using the thread of the normal
> > cap on the outside to which a shape of a 7 psi AH100 pressurized cap
> > fitting was added. It improved the engine cooling in many of the cars
> > that were prone to boiling over.
> >
> > Best regards
> >
>
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