I know a few of you know something about Tachs, because Mike at Skyport says
he's sold a few lately.
Basically, my indications were as follows:
Ran normally for many hours. No deviations from expected values.
One day, I was flying around the local pattern, and on climbout, I noticed my
reading was slightly high (out of limits!!). Pulled back the throttle, and the
tach did not read lower. Checked all other engine indications, and they all
read normal for climbout, idle, etc, etc. Also, the engine "sound" never
changed. It's not spinnin' at 3500 rpm.
I let it sit for a few days because I couldn't get away from work to fly
anyway. Start her up again, and the tach reads 1500 on start, and then only
goes up. You can still hear the drops from the mag check/carb heat, and it
sounds right. The engine is running like a top, it is not the issue. However,
the tach doesn't seem to want to "drop down" to the right reading, it's always
reading high, way out of limits, and even when you shut down the engine, it
takes a bit for it to wind down.
For the experts, and amateurs on this board...where's the issue? Is it the
cable (I do have a slight oil leak that's developed, but it's pretty small and
we're going to isolate it this weekend ("we" being my A&P and myself)), or is
it an internal gear in the tach itself? I have all the logs from the plane
from '46 until now, and the Tach was replaced a bit ago, it's got ~600 hours on
it, but before I got crazy and pay for Mike's kid's to go to college, is this a
gauge problem or a cable issue, or some gremlin haunting me before I have my
bachelor party at Oshkosh? And there's only one right "right" answer, but any
suggestions based on your experiences or ponderances would be most welcome.
Thanks!
-Matt Harting
N2699H
