Mark Steitle wrote:

Ken,
Could the Cadillac, or Corvette, vacuum pumps be used to provide

pressure

as well as vacuum.  If so, the pressure could be used for preflight
checking of the cooling system.  Also, my Lancair ES has need of a

pressure

pump to inflate the door seal.  Am I dreaming or is this a real
possibility?  -- Mark

I think you need about 30 psi to pressure test the cooling system.
According to this smog pump curve the pump is only good
for less than one bar or about 15 psi. It is more of a volume device
than it is a pressure device.

Paul Lamar

Tom Kendall wrote:

I very recently had a cooling system leak on my trusty old truck.  Couldn't
find it to save my soul, but I could smell it and had a lot of antifreeze
residue under the hood all over the place.

Because the leak was small and the weather cold, the system wasn't
pressurizing except at highway speeds, and when I would pull over to check
it, the pressure dropped to zilch before I could get the hood open.

Went down to the local autoparts store and borrowed a tester.  It's a small
hand pump and pressure gauge that hooks up to the rad in place of the
pressure cap.  The cap is 16 psi.  It took two strokes of the hand pump to
get to 5 psi, and resulted in a nice stream of coolant spurting from an old
cracked heater hose.  Worked slicker than otter snot.  Based on that, I
don't think you are going to need much pressure to find coolant leaks!

We found leaks at 20 or 30 psi that did not show at 5 psi on Perry's
cooling system. It is a good idea to run a 25 psi pressure cap
on an airplane where on a car you can get away with a 15 psi pressure cap.
That is because a pressure cap spring is aided in its function by ambient
pressure. In other words it is a relative pressure device. At high
altitudes it will blow off at lower cooling system absolute pressure.

A 30 psi cooling system test is a little extra margin of cooling system safety.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org