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Dave Leonard
Did you see the earlier post today about the relatively cheap - and easy to
install - "coolant flow sensor & indicator"? Might want to spring a few
bucks for that and see if that helps diagnose the coolant circulation
problem.
And/or, how about a temporary "Non-flight worthy" test rig - clear plastic
tubing from high point - or from threaded port in top of water pump - to see
a "sample" of what the pump is putting out? Also, you or someone else
mentioned taking the the hose from engine to radiator loose and letting it
dump into a bucket (with pump sucking from another bucket - held high so
pump keeps a prime) to see what is coming out.
David Carter
----- Original Message ----- From: <daveleonard@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 30, 2004 9:54 PM
Subject: [FlyRotary] Re: One step forward and .9 steps back.
>
> Keeping water level up to the pump and/or eliminating air up there:
>
> I don't think there can be a problem with air in the rads or pump
housing if
> the system is filled from the bottom - from a hose going down from the
> bottom of a "header" tank (pressurized expansion tank) that is at or
above
> the level of the top of the pump.
> - The liquid will go in the bottom of the entire system and force
air
> upward as liquid level rises 'from bottom', and assumng that there is a
> bleed plug at highest spot in engine or pump (removed) or a peck cock
valve
> (opened) during filling. (ideal would be to have a permanent bleed line
> from that high spot into an 'always-partially-filled header tank that
always
> keeps the entire system full of liquid - air has to be expelled.
> - Given, there may be air traps somewhere in the system, but the
liquid
> will either bypass them - or purge them as it keeps rising until it
comes
> out the "high point" (bleed plug hole or pet cock or bleed line
connected
> there and going into the header/expansion tank).
>
> If you don't have such a header tank, then there should be a way to
plumb in
> a "fill hose" that is fitted to the bottom of the system (such as a pet
cock
> with an appendage for putting on a piece of rubber tubing), with "fill
hose"
> running up to be held above engine with funnel in it - or put top end of
> fill hose on bottom of a siphon hose to siphon or pump out of your
coutainer
> of coolant.
> - Fill the system until liquid comes out top of system. Close
petcock
> at bottom of system. Remove fill hose and put it and your funnel and/or
> siphon, or whatever away and then start engine runs to purge any
remaining
> air and keep topping off the liquid level as air is expelled.
>
> Does this make sense? I'm talking about NOT having what I consider the
> ideal system (pressurized expansion tank with fill line going to lowest
spot
> in system and with air vents from highest point in system into expansion
> tank below liquid level). I'm only suggesting that whatever OTHER
system
> you have, permanently install a fitting (valve or pet cock) at bottom so
you
> can temporarily install a removable fill line and, holding the top end
of
> the fill line above the engine & pump, pour in coolant so it goes in at
the
> bottom until it comes out the high point.
>
> David Carter
David,
Thanks for the input. I agree that filling the system from the bottom
should remove most of the air. I have a means of doing just that and used
it most of the times I filled the system, including the time that there was
no coolant flow. I also have a pressurized surge tank connected to the
high-point in the system.
I ran it about 5 times today for short periods trying to burp the system
but there is still a sizeable pocket of air somewhere. If I put 30 PSI of
pressure on the pressurized surge system it will push about a cup of coolant
into the system, but only coolant comes back when the pressure is relieved.
That's probably about 2 cups of air in there somewhere. I'll just keep
trying to burp the system.
Today I went and ran the system after removing the piece of stuck RTV.
Coolant flow still seems anemic because the sides of the rad barely get
warm. There was some flow, however. Coolant temp (measured at the outlet)
would be120 at low RPM and quickly drop to 90 at higher RPM (4000) and go
back up shortly after reducing RPM again. This says to me that the higher
RPM was generating good coolant flow.
I still need another surge tank to catch all the overflow.
I also partially solved the problem of not running well on batteries. I
discovered today that turning off the alternator just makes the mixture a
little more lean (I don't know why yet). But if I just turn up the mixture
about 90 deg it runs great off just the batteries. Shouldn't be too hard to
trouble-shoot now.
Thanks for all the help.
Dave Leonard
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