Troubleshooting EGT Probe?

[crabandy]

My #2 EGT quit (G3X system) after the last test run, it red X'ed on the engine page. I wiggled the wiring and and it showed an erroneous climbing temp compared to the other EGT's that were cooling after shutdown. O-360, prior to first flight about 6 test runs on engine.

-Wiring and connectors look good.
-I swapped the #2 wires to the #4 EGT and the #4 wires to the #2 EGT and the Red X was displayed on #4 cylinder.

I assume there is a way to test the EGT probe with my Ohm meter, but I'm not sure of the values.
Does anyone know what values I'm looking for?
Thanks,
Andy

[Walt]

An ohm meter will show a very low (< 1 ohm) resistance value of a good probe.

[crabandy]

Thanks Walt, one more questions.
-No continuity would equal bad probe?

[Walt]

Originally Posted by crabandy

-No continuity would equal bad probe?

That would be correct.

[rocketbob]

I climbing temp when cooling is a sure sign of a thermocouple hooked up backwards.

[crabandy]

It was hooked up and working correctly for the first 6 or so engine runs, the connectors were still hooked up and appeared secured after I removed the fiberglass sleeve and heatshrink.
Thanks for the reply,
Andy

[crabandy]

After making it out to the hanger with the Ohm meter and the #2 probe (bad probe):
-No continuity between the red/yellow leads
-No continuity between yellow lead and probe body
-Continuity between red lead and probe body

The properly functioning #4 probe showed continuity between both leads and between each lead and the body of the probe.

Will call/email for replacement tomorrow.

[Wayne Gillispie]

Recommendation to all builders...Write down any information from every part you install in your build manual. Also do a little non-destructive testing on things so you will have some baseline readings to go by when you need to troubleshoot down the road. All EGT probes should have loop resistance and millivolt output readings noted. I heated my probes up in a dimly lit shop with a propane torch approx 3" away until they started to glow(1500-1600F), then noted readings.

http://alcorinc.com/wp-content/uploa...e-Rev-2011.pdf

Ask the manufacturer or someone with experience before testing a particular component, as you can cause damage.

[g3xpert]

Originally Posted by crabandy

After making it out to the hanger with the Ohm meter and the #2 probe (bad probe):
-No continuity between the red/yellow leads
-No continuity between yellow lead and probe body
-Continuity between red lead and probe body

The properly functioning #4 probe showed continuity between both leads and between each lead and the body of the probe.

Will call/email for replacement tomorrow.

Hello Andy,

Sounds like a bad probe to us too. We received your email and will get you a replacement.

Thanks,
Steve

[crabandy]

Wow, Thanks!