Jeff Spitzer wrote:

Cooling systems don't carry watches.  They know nothing about time!  If

you

increase the flow and it cools worse then something else bad happened

(like

removing the thermostat on a 13B and feeding the water into the pump
instead of the rad)  Another possibility is that the water is boiling in
the block due to excess heat for a given pressure and the back pressure

is

controlling boiling.   If so then get a higher pressure cap and let it
flow.  Don't back pressure the flow to cover up some other problem.

Pumps

don't "need" back pressure.  That's pure folklore.

Jeff Spitzer

That is worth repeating. "Pumps  don't "need" back pressure."

Paul Lamar

Tracy Crook wrote:

It is true that a pump does not "need" to be designed to have back pressure.
BUT, if it  *is* designed to work with back pressure (and there are lots of
reasons to do so) then operating the pump without that required back
pressure will result in cavitation, less flow, and pump damage.  This was
shown quite clearly on some of the information previously posted.    Anyone
who has worked on their own well pump is familiar with the "churning gravel"
sound of a cavitating pump when the pressure is too low.   If the water pump
output is visible (like in my lawn sprinkler system) the loss of flow is
directly visible.

I'm amazed Jeff.  Did you really mean that statement as unconditional?

Tracy Crook
rws@altavista.net
www.rotaryaviation.com

Yes I did.  I have never seen a pump that needs backpressure to operate.
The thought of cavitation due to reduced back pressure is completely
foreign to me.  I suppose that pumps designed for very high pressure and
relatively low flow (well pumps?) could work improperly at low pressures.
This does not apply to engine water pumps.  I would have to see for myself
what you are talking about.  I will add the condition that no pump
*properly designed for engine pressure ratios* (approx 10 psi) will suffer
from less pressure.

Jeff Spitzer

 
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