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Date: Sat, 19 Mar 2005 10:03:05 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: FD coolant level sensor?
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Bulent Aliev wrote:

> On 3/19/05 10:06 AM, "Russell Duffy" <13brv3@bellsouth.net> wrote:
>
>     Greetings,
>
>     I'm looking for ways to put a coolant level switch in the engine,
>     and remember that the FD had a level sensor. I never looked it one
>     of these before, so I'm wondering how it worked. Does anyone have
>     one they can look at, or perhaps send me if you don't want it?
>     Does is have some sort of float in it? I have an extra 1/4" NPT
>     hole in my upper water pump housing, which would make a great
>     place for a switch, but I haven't found one that seems like it
>     would work there very well. Did the FC use level switches?
>
>     Thanks,
>     Rusty (top secret lower cowl being test fit today)
>
>
> Hi Rusty, I don=92t think coolant level switch should be on your water =

> pump. If the coolant level drops there, it is too late. The pump will=20
> cavitate very very soon. (assuming is the stock pump). I would install =

> it in the expansion tank or overflow tank. When the coolant drops=20
> there you will have more of a chance to head back before the pump gets =

> exposed.
> Buly


The 2nd gen car that's dead in my hangar is dead because I got dependent =

on the 'raise the dead' buzzer that went off when the sensor *in the=20
overflow tank* sensed low coolant. When the upper tank on the radiator=20
cracked & lost coolant while driving, the overflow tank still had plenty =

in it & I never got the buzzer.

This brings up a potentially significant point. Most folks say to use=20
system pressure to detect leaks. I can't say from experience that it=20
works, but I can say that a level sensor in the catch tank *won't* work=20
to detect in-flight problems because the level there isn't likely to=20
drop until the system cools & tries to suck coolant back from the reservo=
ir.

I'll try to take a look at how it works for you some time today when I=20
take a break from doing my taxes. (Weather induced major change of plan=20
from flying down to St Elmo for lunch & SQ2000 inspection. Sorry, Paul.)

Charlie