Cirrus SR20 CHTs too HOT

C

crzepilot

Filing Flight Plan
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Jun 12, 2022
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crzepilot
So I’ll be straight forward, not a huge fan of this aircraft. I don’t fly it too much for multiple reasons which I won’t get into. But I’m trying to dig into this issue….

The club has an SR20 that has had a cylinder replaced about a year ago due to overheating. Thing was torched, since that time, there has been multiple high temperature events flagged on the engine data monitor or reported by pilots. Temps have exceeded 420F but briefly, recently on a warm day, 75F, shortly after takeoff the front cylinder #1 exceeded 420F, plugs were checked, compression checked, induction checked for
Leaks, injectors checked, all looks normal. Run up and two test flights in the pattern yielded nothing abnormal. CHTs usually around 340F but random cylinders will see spikes in temperatures above 390F-420F.

Any suggestions what might be causing random cylinders to run excessively hotter than the others?
 
Could be bad probes or bad instrument. I had to replace my JPI because it was saying I had cylinder temps of 500. There was no way. New instrument, problem solved.
 
First I would check the probe’s connections, they may be loose or dirty. Might want to use a new star lock washers, they’re tiny, M2 or 2.5 I think.
 
Lycoming 390? An angle valve lycoming should cool better than you describe, but CHT's of 420 are not destructive. Doesn't the engine manual say "435 or less for maximum longevity" or something like that?

Assuming your instrumentation is correct, your three options for better cooling are: Make sure the timing is correct. Make sure the baffling is in good shape. Make sure the mixture is sufficiently rich. And #4, make sure whoever is flying it isn't putting it in an extended low speed, high power climb.
 
Also, check mag timing. I once had an issue with hot cylinders (mostly the two rear) and it turned out my mags were off.

+1 on the checking the sensor connection too. I just got my overhauled engine back and was getting some strange hot readings on one cylinder. Turned out the connection was loose.
 
Brad Z said:
Also, check mag timing. I once had an issue with hot cylinders (mostly the two rear) and it turned out my mags were off.

+1 on the checking the sensor connection too. I just got my overhauled engine back and was getting some strange hot readings on one cylinder. Turned out the connection was loose.
Click to expand...
Yay for engine monitors
 
Hey all thanks for your ideas. I really appreciate it and will start looking into my issue starting with timing.
 
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