[alfa] RE: Bleeding air out of the radiator, etc.

["Michael & Carmen Keith" <mikeandcarmen@xxxxxxxxxx>]

Don't have much to offer with regard to you bleeding problem, but I did want
to pass along something that I learned in an automotive technology class
that I took at my local junior college for grins a few years back.  A
radiator cap actually has an expansion valve to allow coolant flow into the
overflow tank as well as a vacuum valve to draw coolant from the overflow
tank into the cooling system as the vehicle cools down.  The radiator cap
does more than merely seal the cooling system.  It is actually a pressure
regulating device.  It uses the expansion & vacuum valves to maintain a
constant system pressure, typically 14 to 16 psi.

My instructor went on to make the point that it is very important to replace
the radiator cap every few years just the same as you do your hoses, etc.
Also, it is VERY important to use a factory cap rather than one of those
aftermarket types from a parts store.  To illustrate his point, he had a
student go to a local auto parts store & purchase about 20 aftermarket caps
of various pressure specifications.  We tested all of them with a pressure
tester to see if they would hold the pressure specified on the cap & not
even one of them did.  So, he took them back to the parts store for a refund
claiming that they were all 'defective.' :-)  He got some strange looks at
the parts counter.

Anyway, good luck with your problem.

Michael Keith
Houston, TX
87 Milano Gold

Boy is this going to sound dumb...but when there is a lot of pressure in
the radiator, the spring loaded cap raises and lets the expanded coolant
into the reservoir. Simple enough. How the hell does it then suck it
back in when it cools down? The bottom of the cap is now sealing off the
hole from the reservoir, so fluid can't be sucked back in when the
coolant cools and 'shrinks', can it?
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