REFLECTOR: Oil Pressure

[Laurence Coen]

John,

Your oil pressure transducer is likely grounded at the engine and your 
readout is grounded to your panel buss.  I suspect the ground potential at 
the panel buss changes with change in load but the same thing doesn't happen 
to the engine ground.  You can check the voltage between the engine and buss 
grounds with varying loads.

Larry Coen
N136LC

--------------------------------------------------
From: "John Dibble" <aminetech at bluefrog.com>
Sent: Friday, July 31, 2009 9:02 AM
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Subject: REFLECTOR: Oil Pressure

> At this point I'm pretty sure I do not have an oil pressure problem.  On 
> the return from
> OSH, my observant copilot noticed that every time I turned a knob the 
> pressure reading
> changed.  So I turned off my radio and the pressure went up 6 psi.  Then I 
> turned off the
> transponder and the pressure went up another 6 psi, making it 51 psig 
> which I am happy
> with.  I checked the voltage drop across the relay and it is 0.  I checked 
> the voltage
> drop between my RMI monitor ground and another ground.  I varied from 
> 0-0.02 v as I turned
> on a few things.  The monitor power voltage decreased from 12.6 by 0.1 
> volt each time I
> trurned on something.  I figure that's just the battery voltage going down 
> with increased
> load.  What do I need to be looking at?
>
> John
>
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