Vaccuum Pressure Gauge

[Al]

Now that its cold again, my vacuum pressure gauge is acting up (again). In
the past, when it was cold, it would take a few minutes to come up to the
correct reading. Now, it takes about 30 to 40 minutes to come up. All
dials are OK, and when the gauge comes up, it reads in the normal range.

Any suggestions or good shops??? Thanks!

Alex
awaddell .a.t. codestrike d-o-t com

[CriticalMass]

Al wrote:

>Now that its cold again, my vacuum pressure gauge is acting up (again). In
>the past, when it was cold, it would take a few minutes to come up to the
>correct reading. Now, it takes about 30 to 40 minutes to come up. All
>dials are OK, and when the gauge comes up, it reads in the normal range.
>
>Any suggestions or good shops??? Thanks!
>


Sounds like it's tired.

Any instrument shop could overhaul it, I suppose - Trade a Plane is full
of them. I'd look at cost new, as well. Aircraft Spruce shows a 2 1/4"
UMA vacuum gauge new for $84.

I always say, replace stuff in our old airplanes with new every 35-40
years whether it needs it or not.

[mikem]

Al wrote:

> Now that its cold again, my vacuum pressure gauge is acting up (again). In
> the past, when it was cold, it would take a few minutes to come up to the
> correct reading. Now, it takes about 30 to 40 minutes to come up. All
> dials are OK, and when the gauge comes up, it reads in the normal range.
>
> Any suggestions or good shops??? Thanks!
>
> Alex
> awaddell .a.t. codestrike d-o-t com
>
>
They use a tiny orfice (jewller's screw driver adjustable, located
thru the NPT threaded fitting on the rear of the gauge) to create
the damping for the needle. If this orfice is too big, the needle
vibrates in step with each intake stroke. If the orfice is too small,
it will do what you describe, especially in cold weather, where
differential expandation (sp?) of the materials tend to close up the
orfice...

The orfice adjusting screw is reachable by removing the 1/8" tube
which goes through the firewall to the induction...

MikeM

[Al]

Buying the new airborne (OEM) is $883.55. Anyone know the legality & fit of
replacing it with a UMA version?

--
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"CriticalMass" > wrote in message
...
> Sounds like it's tired.
>
> Any instrument shop could overhaul it, I suppose - Trade a Plane is full
> of them. I'd look at cost new, as well. Aircraft Spruce shows a 2 1/4"
> UMA vacuum gauge new for $84.
>
> I always say, replace stuff in our old airplanes with new every 35-40
> years whether it needs it or not.

[Michael]

"Al" > wrote
> Now that its cold again, my vacuum pressure gauge is acting up (again). In
> the past, when it was cold, it would take a few minutes to come up to the
> correct reading. Now, it takes about 30 to 40 minutes to come up. All
> dials are OK, and when the gauge comes up, it reads in the normal range.
>
> Any suggestions or good shops??? Thanks!

Assuming this is really a gauge problem (do the gyros spin?) there is
oil and/or crud in the gauge. The only fix is to disassemble, clean
with a solvent (acetone is a good choice, cheap, and available at most
hardware stores), and reassemble. Don't let the acetone get on the
cover (lens) because it will fog.

The most difficult and time consuming part will be removing the gauge
and reinstalling it.

Of course this isn't preventive maintenance, so I would never suggest
that you as an owner should do this.

Michael