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David,
Where and how did you install the air bleed at the high point of the cooling
system?
Bryan
There are two kinds of cooling systems (kinds of "expansion tanks") as far
as I know: 1) the one most people think of and talk about is a
non-pressurized expansion tank that gets fluid when pressure "burps" past
the radiator cap. That is the kind where the fluid gets sucked back into
radiator AFTER engine shutdown (IF there are no leaks anywhere to let AIR
suck in - which would prevent sucking fluid from the expansion tank).
2) the 1998 or so Ford Contour system (and others) where "expansion
tank"/"header tank" is pressurized (the pressure cap is on the tank, not
the
radiator), and it has a tube going down out of the bottom of tank to a T
fitting at bottom radiator hose; also there is a tiny "air bleed line" in
the highest part of the engine (somewhere in the head at the top of the
water passages) that slopes UP into the bottom of the "pressurized
expansion
tank/header tank" - any air at top of engine would flow up into the tank
and
would be replaced in the head by gravity flow of coolant into the system -
coolant level in the expansion tank is slightly above the highest point in
the head's coolant passages.
This "Contour" system would be perfectly safe to have the "coolant level
switch" in the tank. There would be none of the dangers cited for systems
that have the NON-pressurized exp tank.
- Also, none of the "burping" several times after filling as there is
with the "non-pressurized" tanks - in Contour system, you fill thru the
"expansion tank" - fluid runs out bottom and fills entire radiator-engine
block system from the bottom up, with (theoretically) NO air trapped in
any
radiator or engine part as the fluid rises to top of head and then up into
bottom of tank. When fluid in the tank starts to rise, you know th engine
and radiator system is full. Of course, there could be "pockets"
somewhere
or a hose that runs up and back down slightly where air could be trapped -
so an engine run should move the air to top of system, where it would
bleed
into the bottom of pressurized expansion tank, and "burping" would be
done.
- This is what I'm designing for my RV-6/13B aircraft.
David Carter
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