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This is really interesting. I've been saving and infrequently wondering
about an e-mail of several years ago on Paul Lamar's list - A guy reported
that when he changed is plumbing at the radiators (A/C cores?) FROM "in at
the top and out at the bottom" - just like cars - TO "in at the bottom and
out at the top" his engine cooled much better. I've asked a couple of times
why that might be and never received any "bites" in response.
Now I think I have a reasonable explanation: He had air trapped somewhere
in the top of his rad/cores or hoses in that vicinity, which impaired his
cooling; then by reversing "in and out", he started moving the air or air
bubbles out with the flow. Makes sense to me and solidifies my position
that my hot coolant from the engine will enter the BOTTOM of both of my
cores via a Y or splitter in between them, and exit at the TOP of each, into
another Y.
- As a slight embellishment, I think the A/C cores should be tipped 10
to 15 degrees about the longitudinal axis so that "top" and "bottom" are
accentuated and very "definite", with NO HORIZONTAL area for air to be
caught in (IN CORES OR IN HOSES), with continual slight upslope toward the
exit from the core and associated hoses.
- With this setup, the late 90's Ford Taurus plumbing is a snap to
copy: Remove pressure cap from expansion tank (which is pressurized upon
engine start with pressure cap is re-installed after filling system), and
pour coolant in there - it drains down all the way to the BOTTOM of the
radiators, FILLS THEM FROM THE BOTTOM UP, expelling air UP into engine
block, and eventually expelling air out the small fitting we've just been
talking about at the "highest point in the engine", with line from that
fitting running ever so slightly UP to enter the expansion tank BELOW the
coolant level in that tank.
- This, to me, is the PERFECT system. Should eliminate most if not all
"burping" that is required with "older technology plumbing schemes".
David
----- Original Message -----
From: "Mark Steitle" <msteitle@mail.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 02, 2004 11:20 PM
Subject: [FlyRotary] Re: overflow connections
> Paul/John,
> What is the type and configuration of your radiator? What I'm asking is,
> is there the possibility of an air pocket forming along the upper portion
of
> the radiator, thereby reducing your cooling capacity. If air gets in, can
it
> get back out? That is the purpose of tapping off the top of the return
tank,
> to suck the air out of the system and catch it in the accumulator tank.
> The large return hose is typically located on the bottom of the tank.
Unless
> you have a cap on the radiator, how do you ensure the radiator is full of
> coolant
> and not air?
>
> I also installed a manual bleed valve on the thermostat housing. But I
have
> found that the fast-flowing stream of coolant will take any air bubbles
> with it,
> and they will slow down and pocket in the radiator. Hence, the decision
to
> draw it off the top of the radiator return tank.
>
> Of course, if you're using heater cores, this may not apply. I'm using a
> conventional cross-flow radiator, tilted forward at about 30 degrees.
>
> Mark S.
>
>
>
> At 02:16 PM 3/2/2004 -0600, you wrote:
> >To continue to beat up on this "air vent line from top of engine" - its
been
> >made clear that the line should not be large. I'd treat it like I would
a
> >"direct oil pressure gage": If the oil line to gage breaks, you don't
want
> >to dump all your engine oil out a big broken line, so folks use very
small
> >lines and even put in restrictors.
> >
> >Well, in this air/steam vent line, the issue is not breaking and
dumping -
> >rather, it is "bypassing the radiator". So, to minimize coolant that
> >doesn't get cooled, then either use the smallest possible line, or, as in
> >the oil pressure tubing, put in a restrictor. Air doesn't need much of a
> >hole to flow up to your vent tank.
> >
> >For my education, Kelly, how big is a -3 hose? 3/16 ID?
> >
> >David
> >
> >----- Original Message -----
> >From: <keltro@att.net>
> >To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> >Sent: Tuesday, March 02, 2004 12:14 PM
> >Subject: [FlyRotary] Re: overflow connections
> >
> > > > The input I got about the expansion tank was to plumb the lower
> >connection
> > > > down to the radiator and the upper connection to the top of the
block.
> > > > That's what I did, and apart from the problems I had with the
> >thermostat, it
> > > > seems to work fine. I have a 23 lb cap on the expansion tank and a
small
> > > > overflow bottle.
> > > >
> > > > Regards,
> > > > john
> > > >
> > > Paul and John,
> > >
> > > Let me expand on this subject. The input I have said to plumb
the
> >bottom
> > > fitting of the expansion tank to input (suction side) of the water
> >pump/radiator
> > > to keep system pressure seen by the pressure cap to a minimum. The
upper
> >expansion
> > > tank fitting should be small (-3 an hose or not over 3/16" I.D.) and
> >connected
> > > as John said to the top of the engine block. Its function is to bleed
any
> >trapped
> > > air in the system to the tank. IMHO
> > >
> > > Kelly Troyer
> > >
> >
> >
> >
> > >> Homepage: http://www.flyrotary.com/
> > >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
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