EGT Gauge Problem

[Doug Rohrer]

Here is a question for the two or three RV drivers still flying behind steam gauges like me. My Van's EGT gauge is hooked into the #1 exhaust pipe. I usually get no reading (lower peg), sometimes I get a realistic reading and sometimes the needle wanders around aimlessly. I replaced the probe with a new one with no improvement. I have checked all connections to the gauge and made sure the Faston connections are good and tight under the cowl. I am looking for ideas what the problem might be. When I pull the probe out and heat it with a torch, I get a reading, but then nothing when I fly. Bad gauge? How to test? Thanks.

Doug
RV-9A

[longranger]

Did you run thermocouple wire all the way back to the gauge? If there's a thermocouple to copper junction in the engine compartment getting hot along with the probe, the output reading will be reduced, and/or wander around.

[Vlad]

Double check the connector if you use extension to thermocouple wire. I had erratic reading a while ago and traced the problem to bad connection.

[Doug Rohrer]

The builder did use thermocouple extension wire to go through the firewall to the gauge, but there are Faston spade connectors making the joint. I believe it is OK to have these connectors in the line as long as they are in both legs and at the same temperature. I will recheck joint integrity, but I have already done this.