BigBadLou
Final Approach
- Joined
- Aug 6, 2014
- Messages
- 5,166
- Location
- TX - the friendliest state
- Display Name
Display name:
Lou
I have a 4 EGT (and CHT) probes on my IO-360 and a JPI "classic" (understand: "1980's") scanner. So not 700-series or 800-series monitor, nothing that fancy.
The #4 probe never read right even since I got the plane. The previous owners claim they never used the monitor (let's not go there anyway).
The old #4 probe read a dot (a dot in the 1st digit) and then usually zeros or some small value. Sign of a bad probe.
I disconnected #4 and #2 probes from the monitor harness. I swapped the probes on the harness.
Now #2 reading was bad and #4 reading was good. Thus eliminating the JPI monitor or its harness.
I bought a new probe and installed it in the exhaust pipe on #4 cylinder. Connected to the monitor and now #4 reads, again, some low value. I performed the same swap test as before and the new probe reads bad on #2 input and the #2 probe reads good on #4 input.
Installation manual for the JPI monitor says that a probe that reads low, approx 100F, is a bad probe or open circuit.
Probe measures <2.0 ohms per specs across open terminals (out of circuit).
Questions:
1) what are the chances that I got a dud out of the box?
2) does anybody have experience with Alcor M-111 EGT probes?
3) what next step would YOU take in my situation?
I will bring a small pencil butane torch with me to the hangar next time and measure the actual voltage on the good #2 probe and the new #4 probe.
Thank you in advance for any useful advice.
The #4 probe never read right even since I got the plane. The previous owners claim they never used the monitor (let's not go there anyway).
The old #4 probe read a dot (a dot in the 1st digit) and then usually zeros or some small value. Sign of a bad probe.
I disconnected #4 and #2 probes from the monitor harness. I swapped the probes on the harness.
Now #2 reading was bad and #4 reading was good. Thus eliminating the JPI monitor or its harness.
I bought a new probe and installed it in the exhaust pipe on #4 cylinder. Connected to the monitor and now #4 reads, again, some low value. I performed the same swap test as before and the new probe reads bad on #2 input and the #2 probe reads good on #4 input.
Installation manual for the JPI monitor says that a probe that reads low, approx 100F, is a bad probe or open circuit.
Probe measures <2.0 ohms per specs across open terminals (out of circuit).
Questions:
1) what are the chances that I got a dud out of the box?
2) does anybody have experience with Alcor M-111 EGT probes?
3) what next step would YOU take in my situation?
I will bring a small pencil butane torch with me to the hangar next time and measure the actual voltage on the good #2 probe and the new #4 probe.
Thank you in advance for any useful advice.