----- Original Message -----
Sent: Wednesday, October
03, 2007 6:08 AM
Subject: [FlyRotary] Re:
Coolant Water Pressure
I think that I would see air under the
radiator cap if I had a compression gas leak? I never see any air.
To check a piston engine for head gasket
leaks, you would put the cylinder at TDC and pressurize the cylinder to about
150 lbs with compressed air and check the radiator for air bubbles…How do
you check a rotary?
I will check the pressure sender against a
mechanical gage.
There is obviously a heating problem, but
I think the pressure is higher than it should be until just ready to
boil. I shut the engine off at 210*, and at 22+ lbs, the boiling point
should be well above 250*??
Thanks for the suggestions of where to
look, guys…
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Al p Wick
Sent: Tuesday, October 02, 2007 7:49
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Coolant
Water Pressure
Your coolant reservoir should be above engine.
1) If it is, remove two cups of air from the reservoir. Then repeat
your test.
2) If you now see pressure rise above 22 psi within 5 minutes of
cold start, you clearly have compression gases leaking into cooling system or
bad gage.
3) Air in the block is 10 times more significant than any other cooling
factor. Make darn sure you don't have any. It causes local boiling, high temps,
strange behavior.
Operating with two cups of air under cap is an important safety and
diagnosis advantage. Everyone should do it. With that two cups, you only see 22
psi if you have a genuine problem. You only see 0 psi if you have genuine problem.
The pressure is then a very fast and reliable indicator of system integrity. So
two cups of air has no negative effect on system efficiency, just a substantial
improvement in safety. Only time it could be a negative would be if your
reservoir was way too small, way too low, or flowed way too much coolant.
Since you describe high temps AND pressure, I suspect you have
temperature problem.
I deliberately overheated my engine many times so that I was intimate
with pressure and temperature patterns. Then tested various concepts.
Don't recommend you do the same.
I just recently got my Renesis started again after finishing
my cowl. I seem to be getting very high coolant pressures. I can
only run the engine about 10-15 minutes before hitting the redline at
210*. My water pressure is at 27 Lbs at that time. I only have a 22
Lb radiator cap, so I assume that I am blowing into the recovery tank, but I
have not confirmed that. My oil temp has never exceeded about 165*.
It might have gone higher if I could have run longer???
This whole water pressure thing has me a little
baffled. Since this is a closed system and the only way pressure can
build is due to the expansion of the coolant after heating???, I am confused by
some comments that have been made from time to time. I remember something
that Tracy said
about his pressure would build for a time, then go to zero. It seems to
me that the pressure should correlate to the temp pretty closely since it is a
closed system??
Can someone enlighten me a little on the science of this
pressure? It seems to me that there could be some pressure build up on
the positive side of the pump, but it would go negative on the suction side, so
the net effect of the pump should be close to zero??
Also, my Renesis had only 1800 miles on it when I bought it,
so I did not have to tear it down. As a result, I am somewhat in the dark
as to how the water flows through the system. Could someone help me with
that? I had to remove the thermostat tower for height clearance , so I
made an adapter plate that takes water from the top outlet of the pump and sends
it to the radiator (double pass), then from the radiator, it returns to the
lower inlet of the pump.
Thanks,
Bill B
-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam timing.
Artificial intelligence in cockpit, N9032U 240+ hours from Portland, Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html