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Hi John,
A couple of things. Tracy and I both discovered that
one ALL the air is out of the coolant system, the coolant pressure may jump to
21 psi almost immediately upon start up - long before the heat would cause it to
build to that point. At first, I thought "coolant Leak", however, I could
never find any evidence of coolant in the chambers nor loss of coolant in the
system. Talking to Tracy Crook, he reported the same thing. We came
to the conclusion that without a small cushion of air that the pressure sensor
was seeing hydraulic pressure caused by the pump. With no air cushion even
a small disturbance would likely cause the pressure sensor to indicate high
pressure. As the block and components heated up the coolant volume got a
tiny bit larger due to expansion of parts and the hydraulic pressure
quickly decreased. At least that was
the best theory we could come up with at the time.
During flight the pressure would quickly decrease
until it was below 10 psi and on cool days would got to zero.
On my flight back home (some air still in system), the
coolant pressure never got above 12 psi (right after take off when hottest) and
most of the time ran at 8 psi. So if you are seeing a nominal
10 psi and only seeing the 25 psi on startup, I don't think you have any problem
especially if no evidence of coolant in exhaust stacks.
Ed A
----- Original Message -----
Sent: Friday, June 24, 2005 1:44 PM
Subject: [FlyRotary] Re: Engine Rebuild -
Coolant Leak Cause
supported by the fact that I had notice my coolant
pressure increasing on the flight to Charlies by approx 11/2 psi per hour of
flight. It started at a normal 10 psi and had increased to18 psi by the end of
the flight.
Ed, this paragraph caught my attention. I've been
seeing high coolant pressures lately and am wondering what is normal. In two
or three hours of ground running and one flight I've noticed that the coolant
pressure climbs fairly quickly to around 25PSI or even a little more, and seem
to be throttle dependant. I have a 24psi cap, but never see it release any
fluid. During the flight I checked while airborne and saw about 10 PSI each
time I looked. I haven't lost any coolant or oil.
Regards
John
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