EGT Sensor

[jiott]

I have been getting a temporary failure of my left EGT sensor reading occassionally. It is usually soon after startup and after about a minute it reads normally. Does this mean the probe is going bad, or should I just take it out of the exhaust pipe and clean the probe or something? Do these things need periodic cleaning? I imagine they get some carbon buildup on them.

It is a Dynon Skyview system using Dynon supplied EGT probes for my Rotax 912s.

[jiott]

Just tickling this one in hopes of some replies.

[jrevens]

Hi Jim,

As I'm sure you know, EGT probes are commonly thermocouples. They can & do go bad of course, but usually when they fail, they fail. They are very simple devices - simply 2 specific dissimilar metals (the wire leading into them itself) which are welded together at the end, creating a "junction". This hot junction is then encased in a shroud which is the probe itself. If the junction is degraded over time, from heat & oxidation for instance, the probe can have decreased output voltage but probably wouldn't be intermittent in operation. Anything is possible, but it's most likely that you either have a bad connection somewhere or a faulty gauge. I suppose you could have a broken wire under the insulation that is making & breaking contact with heat & vibration. Thermocouple wire is usually stranded & can withstand a reasonable amount of flexing. You might want to look at any areas of the wire run that may be flexing a lot.

Carbon can build up on them, but I believe as a general rule that they usually don't require cleaning. I wish I could be of more help than that.

[t j]

Can you switch the connection to the probes between left and right to determine if it is a prob or a gauge problem.

[Wheels]

My EGT gauge died at 1051 am. Then it came back to life and lived just like its 2 brothers for about a half hour before going away again. this gauge is located with the now deceased oil pressure gauge in my Westach Quad gauge set up. I am thinking the quad gauge is going out one instrument at a time but before I try a ton of wrong trouble shooting, I'll check all the grounds again and maybe switch the probes around to see what I get. Having just removed and replaced the engine mount disturbed every wire feed I have so I am not surprised to see some weirdness. Just want to isolate the real problem.