----- Original Message -----
Sent: Sunday, April 16, 2006 3:04
PM
Subject: [FlyRotary] Re: coolant header
plumbing
I'm currious if this will
work, or if I will get air to the wrong places.
Hi
Chris,
I would suggest that you
use a tank, mounted to the top of the firewall if possible, so the fill cap
will be the highest location. It's not a show stopper if you can't put
it there, but it will make filling the system much more difficult if the fill
cap isn't the highest point.
The tank would have the pressure cap, with it's
overflow hose going to the bottom of any old overflow jug. It would
also have two other small nipples for hoses. One would be at the very
bottom of the tank, and would connect to the hose you labeled as "bottom
of overflow tank". The second nipple in the tank would be near the
middle (top to bottom). This would connect to the hose you labeled as
"top of overflow tank".
The idea is to use this pressurized tank to removed
all the air from the system, and it's the way Mazda did it on the FD.
The two hoses in your picture are connected to opposite sides of the water
pump, so they aren't at the same pressure. When you connect these
both to a tank, there will be flow through the tank. Since this bypasses
the radiator, you don't want these to be very big.
What happens is the water (with air bubbles) flows
from the top of the system, into the middle of your tank. The air
bubbles go up, and the coolant goes down. The return flow to the engine
goes out the bottom hose in your tank, so nothing but coolant is
returned. The air is collected at the top of your tank, where the
pressure cap is. During normal heat cycles, the air will get pushed out
into the overflow jug, and coolant will get sucked back in when the engine
cools.
BTW, Mazda called this (amazingly enough) an "AST" or
Air Separator Tank.
The AST tank doesn't have to be large. Even a
pint would do, but I'd try to go a bit larger than that. Taller rather
than wider would be a plus as well. The plastic overflow jug
should be at least a quart, or better a quart and a half.
Cheers,
Rusty (hanging heavy expensive object on the nose
now)