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
>