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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/
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