Cyl head temp

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drmax

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drmax
0-320. Lean out at 10k feet yesterday noticed my #4 cyl head temp under 200 while others at 300+. Rv9a vans, standard build. All rtv sealant in place. It was a cooler day, especially at altitude. Do I need to be concerned? I'd throw another probe on it but don't have one. Engine sounds fine. A bit inexperienced here and don't wanna ruin something. The engine has 550 hours on it brand-new from Lycoming. I think it most likely ran that temperature all the time now I'm just curious thanks DM
 
swap probes and see what happends
 
Under 200 is cold. I am no expert (though I also own a RV-9A), but random thoughts are:
check compression in the cylinder to make sure you are burning the fuel in there and do not have an exhaust leak..
check the plugs in the cylinder.
check the mags when cold.
check the sensor or possibly swap sensors to test.
check the baffles.

Typically the rear cylinders we would expect to run warmer, but oddly in the RV's the #2 seems to frequently be the hot one.
 
No way that cylinder is really that cold unless it's dead, and you would have noticed that in several other pretty obvious ways. Sounds like an instrumentation problem. As they said, swapping probes is the first step in isolating the problem.
 
Upload your data to savvyanalysis.com and then you can view it and see how long it has been that way.

Then, if you want more opinions, opt to make your data public so we view the data.

Swapping probe cables is even easier than swapping probes -- you could start with that to see if your problem is a bad connector. Then swap probes.
 
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NoHeat said:
Upload your data to savvyanalysis.com and then you can view it and see how long it has been that way.

Then, if you want more opinions, opt to make your data public so we view the data.

Swapping probe cables is even easier than swapping probes -- you could start with that to see if your problem is a bad connector. Then swap probes.
Click to expand...
I'll pull cowling to have a look. I'd guess resistance bad in probe. Engine does not run ruff. Mag ck is good
 
Ron Levy said:
No way that cylinder is really that cold unless it's dead, and you would have noticed that in several other pretty obvious ways. Sounds like an instrumentation problem. As they said, swapping probes is the first step in isolating the problem.
Click to expand...

:yes:
 
May have been thinking backwards. 2 & 4 are on left side, correct? I was thinking 1 & 3 yesterday. Oil cooler sits behind #4. This rush of air bound to make 4 colder. Going to swap probes today for hell of it. There most likely is nothing wrong, just be worrying
 
Ron Levy said:
No way that cylinder is really that cold unless it's dead, and you would have noticed that in several other pretty obvious ways. Sounds like an instrumentation problem. As they said, swapping probes is the first step in isolating the problem.
Click to expand...

:yeahthat:
 
Does it have the same probe as the other four? My IO-550 has threaded probe for all the cylinders other than #3 because the #3 cylinder has the "stock" CHT in it. It uses one of those plug gasket probes to drive the engine monitor.

Lycoming cylinders are numbered from the front and the right side cylinder is the first one. Of course, that presumes that whoever hooked up your engine analyzer made the numbers match Mr. Lycoming's.
 
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after all this time, noticed this thing jumping around from 300 to 0. Will finally be replacing all with garmin eng harness kit to g3x. Getting rid of this rotory select indication gage, along with 8 yr old probes, hopefully will cure. DM
 
How lean did you get? You may have leaned enough to drop the power off that cyl.
 
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