I don't believe the pressure will be higher with a 10lb cap. If the 7lb cap
wasn't opening the 10lb cap won't either
(except when you shut the engine off and 'latent' heat causes the coolant temp.
to rise).
I don't believe the pressure cap is there to regulate pressure, only to provide
a bit more margin from boiling, plus
holding some pressure probably assists the pump and coolant circulation.
Bob
On 3/29/2013 7:33 AM, Oudesluys wrote:
> The higher pressure may perhaps affect the expanding of the bellows causing
> it to open at a higher temperature. This
> may be why it is recommended that a 7lbs rad cap should be used.
> However I have known cars that did not have issues with a 10lbs cap.
> Kees Oudesluijs
>
>
> Op 29-3-2013 15:09, Bob Spidell schreef:
>> Doesn't make sense, at least according to the laws of physics I pretend to
>> understand.
>>
>> If you didn't boil or lose coolant with a 7lb cap, it means you never
>> reached 7lb. pressure in your cooling system.
>> So the 10lb cap should never open, either. The additional 3lbs pressure
>> would only give a few more degrees before
>> boiling, which doesn't appear to be an issue with your car (Law of Physics:
>> the boiling point of a fluid is directly
>> related to ambient pressure; that's why boiling cooks foods slower at higher
>> altitude).
>>
>> IOW, the cap doesn't regulate pressure in the cooling system (like a voltage
>> regulator)--it's there to keep your
>> hoses, etc. from exploding if your engine overheats.
>>
>>
>> Bob
>>
>
>
--
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Bob Spidell San Jose, CA bspidell@comcast.net
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