Interesting!
The left CHT gauge on our Aztec started acting the same way. It hangs down
around 250 - 300 degrees and just kind of bounces around never indicating a
steady temperature. Normally they both run around 380 and the needles are
rock solid. Both engines have the standard single probe.

Recently, I changed spark plugs on the left engine and noted that we would
soon be needing new harnesses. Some of the wires were getting a little
frayed near the plug connectors. If one of the wires is shot, could a non
firing plug on the cylinder that the probe is installed in also cause the
symptoms that I am seeing on our CHT?

Run ups are good, no missing or roughness noticed.

Jim Burns

wrote in message
oups.com...
I am stumped as to what could be causing thing and am hoping someone
here can help me out.

A couple of flights ago I noticed that my EGT gauge started
fluctuating. Not fast but up and down a couple needle widths every
second or two. Then on the next flight I noticed that the tach has
started as well. Up and down 25 rpm or so.

I just had a cylinder overhauled about a hundred hours ago and I do
have have a much larger drop in the right mag that I need to clear to
get to normal on each flight.

My mechanic looked at my plugs last week and cleaned one he said that
had oil on it from the overhauled cylinder. I took it flying today to
see if that cleared the problem but it is still there.

Any ideas or thoughts?