Today's Message Index:
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1. 04:16 AM - Re: 912 Cylinder head coolant temperature Gauge (MacDonald Doug)
2. 05:31 AM - Re: Re: 912 Cylinder head coolant temperature Gauge (John Hauck)
3. 12:52 PM - Re: 912 Cylinder head coolant temperature Gauge (rampil)
Message 1
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| Subject: | Re: 912 Cylinder head coolant temperature Gauge |
Another source of temperature spikes I have found is with the absolute jun
k VDO gauges that tend to develop erratic needle swings as they age.=C2-
I spent one summer changing out well over 1000 dollars worth of electrical
components chasing "voltage spikes" on=C2- my CH-701 only to find out the
problem was a bad VDO gauge.=C2- I had even tried another (albeit used)
VDO voltage gauge and still had the same "spikes".=C2- Turned out it was
the crap VDO volt meters and there was actually nothing wrong with my elect
rical system.=C2- Since then, I have been slowly converting my panel over
to Stewart Warner gauges and have been happy with the results.=C2- I hav
e an erratic oil temperature gauge right now that will be getting replaced
at annual.
While I won't claim to be an expert and know very little of the OP's proble
m, he did mention he has a VDO gauge and I would replace that before gettin
g to carried away chasing a potentially phantom engine problem.
Doug MCH-701/ 912-UL
Message 2
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| Subject: | Re: 912 Cylinder head coolant temperature Gauge |
Since the early days, ultralight pilots have freaked out over instrument
indications. They spent hours and lots of money, and probably destroyed
lots of engines and airplanes chasing engine instruments, trying to get
that two stroke engine dialed in perfectly. I think of all the other
two stroke engines in my life back then that had no instrumentation.
Never worried about EGT and other temps. They seemed to run forever
with good fuel and oil, and a new spark plug every once in a while.
Usual the problem was improper prop loading. Rotax did a good job of
setting up the engines at the factory, but if the Westach instrument
told them their EGT was a little high or low, they'd start chasing their
tail, changing jets, needles, spark plugs, and anything else they could
find to change. I was one of them.
I have a situation with my 9121ULS that irritates me. I randomly get
low oil pressure and high engine oil temp indications. I was on a
flight to Oregon many years ago when this first started happening. Was
irritating, but proved to be harmless. It is still happening, but the
temps are always reading the same, even though they are incorrect.
Annoying, but not critical. BTW, they are VDO marine gauges. I can
shut down the battery and the indications return to normal. Must be
wiring, probably poor grounding, or the gauges.
john h
mkIII
Titus, Alabama
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of
MacDonald Doug
Sent: Wednesday, April 18, 2018 6:16 AM
Subject: RotaxEngines-List: Re: 912 Cylinder head coolant temperature
Gauge
Another source of temperature spikes I have found is with the absolute
junk VDO gauges that tend to develop erratic needle swings as they age.
I spent one summer changing out well over 1000 dollars worth of
electrical components chasing "voltage spikes" on my CH-701 only to
find out the problem was a bad VDO gauge. I had even tried another
(albeit used) VDO voltage gauge and still had the same "spikes". Turned
out it was the crap VDO volt meters and there was actually nothing wrong
with my electrical system. Since then, I have been slowly converting my
panel over to Stewart Warner gauges and have been happy with the
results. I have an erratic oil temperature gauge right now that will be
getting replaced at annual.
While I won't claim to be an expert and know very little of the OP's
problem, he did mention he has a VDO gauge and I would replace that
before getting to carried away chasing a potentially phantom engine
problem.
Doug M
CH-701/ 912-UL
Message 3
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| Subject: | Re: 912 Cylinder head coolant temperature Gauge |
My 2 cents as an EE:
There are NO rapid temperature changes. Not physically possible.
How much energy do you think is available to heat and COOL the coolant
through wide swings.
VDO are cheap crappy mechanical gauges, emphasis on cheap crap.
Automotive or snowmobile quality, no better. I like Rotax hardware, but the
VDO garbage should be thrown away on delivery and replaced with
airworthy meters.
The temp. swings are most likely vibration induced mechanical resonances
in the needle/coil/spring system in the indicator.
--------
Ira N224XS
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