CHT thermocouple question for tech gurhus

[Larry DeCamp]

My MGL supplied cht probe for #1 reads exactly the same as 2,3,4 at ambient temp. Flying, the other three are approximately 300F and #1 is less than 100F.

They all terminate in omega flat spade connectors, then on to the cht/egt instrument on the panel. My guess is a high resistance screwed terminal in the Omega connection, or cold solder joint in the DB at the instrument. I assume I can validate the problem and the cure with boiling water.Any advice before I start tearing things apart ?

[longranger]

Sounds like you may have a short circuit in the thermocouple leads somewhere between the probe and instrument. The instrument will read the temperature at the point of the short circuit, which is why you read ambient correctly, and continue to read near ambient in flight.

[Larry DeCamp]

Will try to understand the science you have cited and investigate. Thanks much.
..Larry

[TomVal]

Larry,

A quick check switch CHT1 with CHT3. Do the switch at the spade connectors. If you have the same results on cylinder 3 CHT instrument readout, then it is a simple matter to just replace the faulty probe.

[Larry DeCamp]

Great suggestion and not even a screw driver required. I love VAF.