On Mon, 22 Apr 2013 05:29:32 -0700 (PDT), "
> wrote:

>On Apr 21, 11:15*pm, wrote:
>> On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "
>>
>>
>>
>>
>>
>> > wrote:
>> >On Apr 21, 6:11*pm, Tony Hwang > wrote:
>> >> Ashton Crusher wrote:
>> >> > I was thinking of putting a higher pressure cap on one of my cars to
>> >> > increase the factor of safety against boiling. *Looking thru the web
>> >> > for info on the likelihood of changing from 7 psi to 13 psi causing
>> >> > leaks I found little on that issue but did find a couple references to
>> >> > the pressures created by the water pump. *One site boasts of a 19 PSI,
>> >> > $25 cap to get you thru your "hard driving".
>> >> >http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
>> >> > Thought I'd see if anyone else has heard of this. *The claim was that
>> >> > the water pump could create over 30 PSI of pressure. *Since that is
>> >> > double the normal operating pressure of most modern cars I find it
>> >> > hard to believe. *If the system was at full 15 psi of pressure while
>> >> > the car is idling and then your floored it and ran it up to near
>> >> > redline * and created another 30psi of additional pump pressure, or
>> >> > even 10 psi of additioingnal pressure downstream at the radiator cap, you
>> >> > would immediately cause the system to have to vent to the overflow to
>> >> > relieve this higher pressure. * I've never seen a car vent due to me
>> >> > revving the engine up while I'm working on it. Thoughts?????
>>
>> >> Hi.
>> >> There is a over flow bottle for coolant/anti-freeze. Ever
>> >> cleaned/flushed your rad. and maintain proper level of
>> >> coolant/anti-freeze in your rad.? If the car is old, messing with cap
>> >> can spring
>> >> a leak.- Hide quoted text -
>>
>> >> - Show quoted text -
>>
>> >AMEN!
>>
>> *A water pump cannot produce system pressure because it just moves
>> water from one side of the pump to the other. Expansion due to heat is
>> what builds pressure..- Hide quoted text -
>>
>> - Show quoted text -
>
>You might want to rethink that one. Water isn't going to
>move through a system without pressure to push it. I wouldn't
>expect the pressure to be very high, but there has to be pressure
>due to the pump.
>
>As for the question at hand, what is unstated is if there is
>actually a problem, ie is the car overheating? If it is, then
>finding out the cause of that instead of trying to raise the
>boiling point of the coolant via pressure would seem to be
>the better approach. For example, if he has a bad thermostat
>or collapsing hose, he'd be just covering up the real problem.

No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it. Just to give a bigger margin of safety when the
temps here get up to 110. The manual for the car lists the 7 pound
cap for non-ac cars and the 13 pound cap for AC cars. Just curious if
anyone has ever seen this increase in pressure cause an immediate leak
to happen. The Radiator was rebuilt 10 years/10,000 miles ago. The
heater core is factory original. Now, on a 95 degree day it's running
up to 205 on the freeway and 195 around town. Thermostat is 180.