I'm trying to troubleshoot something that recently occurred and hoping someone has some advice. I fly a 65 235 with 3200 hours on the airframe and powered by an O-540 that is 2100 SMOH. Routine oil changes now every 35 hours with oil and oil filter analysis at every change. No metal has ever been detected. Last annual was in August 2023 and all cylinder compressions were good. Nothing major from the annual but the exhaust was fully replaced. I've got an EDM-830 installed and typically, cylinder 5 is always my hottest cylinder but it's not a problem to keep it below 400. Sometimes in climb after takeoff, it will get up to 405 but if I lower the nose, that will take care of it. Makes sense since it sits in the rear part of the engine.
All flights since the annual have been normal but about a month ago, I took off and noticed cylinder 3 shot up to 420 almost immediately after takeoff, then it went quickly to 415 so I lowered the nose and kept an eye on it. After leveling off, it was difficult to keep it below 400 and the temps would change a bit quicker than I thought they should. I've never had a problem with this cylinder before. A few days later on another flight, it didn't do this...it was still the hottest cylinder but not as extreme as it was before. A few days later on another flight, it did the same thing where it shot up to 420 immediately after takeoff and fairly erratic readings
I'm not noticing anything different from a power perspective so I'm of the opinion the probe may be faulty. How difficult is it to switch the connection of that probe with another one to see if it happens on another cylinder? I also subscribe to Savvy Analysis so will download data today and send off. I wanted to poll this group to ask for any other tips/advice? Thanks
UPDATE...
I subscribe to SavvyAnalysis and uploaded my recent data. The answer came back quicker than expected…
“When CHT goes up like this, it is consistent with a very fouled plug that is igniting the fuel/air mixture a little early. It appears the plug has weak spark for a period after the initial high CHT, as indicated by higher EGT. As you were leaning for cruise, its EGT went up for a short period again.
Recommend cleaning/inspecting both plugs in #3”
All flights since the annual have been normal but about a month ago, I took off and noticed cylinder 3 shot up to 420 almost immediately after takeoff, then it went quickly to 415 so I lowered the nose and kept an eye on it. After leveling off, it was difficult to keep it below 400 and the temps would change a bit quicker than I thought they should. I've never had a problem with this cylinder before. A few days later on another flight, it didn't do this...it was still the hottest cylinder but not as extreme as it was before. A few days later on another flight, it did the same thing where it shot up to 420 immediately after takeoff and fairly erratic readings
I'm not noticing anything different from a power perspective so I'm of the opinion the probe may be faulty. How difficult is it to switch the connection of that probe with another one to see if it happens on another cylinder? I also subscribe to Savvy Analysis so will download data today and send off. I wanted to poll this group to ask for any other tips/advice? Thanks
UPDATE...
I subscribe to SavvyAnalysis and uploaded my recent data. The answer came back quicker than expected…
“When CHT goes up like this, it is consistent with a very fouled plug that is igniting the fuel/air mixture a little early. It appears the plug has weak spark for a period after the initial high CHT, as indicated by higher EGT. As you were leaning for cruise, its EGT went up for a short period again.
Recommend cleaning/inspecting both plugs in #3”
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