High CHT

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1 week 5 days ago #2847 by Michael Stoklosa
Replied by Michael Stoklosa on topic High CHT
I have a 1979 TR182RG w 1500 hours on the engine. I just purchased the bird in September of 2020 and was not sure what to expect on CHT. The original INSIGHT engine analyzer was failing and unreliable I replaced it w a new INSIGHT G2 and all new probes. Im now getting accurate data. I have struggled keeping cyl #1 below 400; usually runs 409 the others range from 330 to 390. I usually fly at 8000 to 10,000 with cowl flaps open and 25 manifold and 2350 rpm prop (3 blades). I keeps cowls flaps open because of temperature concerns. I just replace all the sparks w new and was amazed at the drop in CHT. #1 cry has dropped to 386 and all the other cylinders temps have dropped. Just wanted to pass this info on. I real appreciate this discussion since this is all new to me. Thanks

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1 month 5 days ago #2812 by George Scavella
Replied by George Scavella on topic High CHT
I have a 1998 182S model and seem to have the same issue as yours. After covering all the bases, many of which have been mentioned in this thread I finally had a breakthrough. In the process of bore-scoping my #4 cylinder, it was found that the exhaust valve was not opening as wide as the other cylinders. This was pretty bad news as it indicates a worn camshaft but at least it hopefully solves the mystery of the higher CHT's on this cylinder. Unlike your engine, mine has 2010 hours on it so I guess the engine is telling me it is time for an overhaul. Hopefully this is not the case for you, but it may be worth a look see to see if there is some issues with the cylinder breathing properly.

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1 month 2 weeks ago #2788 by ALLEN BELL
Replied by ALLEN BELL on topic High CHT
Yes, number 4 is always the hottest and 1 and 6 are the coolest.

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1 month 3 weeks ago #2776 by Stephen Warden
Replied by Stephen Warden on topic High CHT
Allen
My cruise performance charts, like yours, are at peak EGT....somewhere along the way, I was told that Lycoming prefers 50 - 100° rich of peak....so I opted for 50....not sure it matters either way unless you are worried about your hottest CHT....which I am.
Your 20° spread in CHT's is great....I'd be very happy with that....I'd fly my plane exactly like you are doing if I had those numbers.

Is your HOTTEST CHT #4?

Thanks
Steve

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1 month 3 weeks ago - 1 month 3 weeks ago #2775 by ALLEN BELL
Replied by ALLEN BELL on topic High CHT
That is how I run my motor as well, with a couple exceptions. The POH and Lycoming recommend “peak” EGT. If you know something better, I would like to know (not being a smartalec but truly inquisitive) My cow flaps settings are very similar. I am also getting about 10.5 GPH at 6,000 feet. Just a reminder, I have a C-182S.

I took my airplane for its annual yesterday. I talked with a highly regarded A&I on the east coast. He said a 20 degree spread in EGT was not a big deal. I know yours is a little more, but mine is 361 to 385 and that is what I used in our conversation.

Still doesn’t explain why #4 is hottest. Like you I would like to understand this.
Last edit: 1 month 3 weeks ago by ALLEN BELL.

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1 month 3 weeks ago #2769 by Stephen Warden
Replied by Stephen Warden on topic High CHT
Hello guys

I have flown a couple of other Lycoming Skylanes, and their temps seem to be all over the place. Some planes have a very tight CHT range, and some have a very wide one....the hottest varies.
That coupled with the fact that I have looked everywhere for a reason for my situation and cannot find anything, I have accepted this as 'my normal'.

This is what I am doing....
I typically fly at 22-23MP 23RPM
I lean to 50° ROP....this consistently yields about 14 GPH
I open cowl flaps to keep cyl #4 at about 380°F (in cold weather about 1/3 open...I suspect closer to 3/4 as summer gets here)

I see a delta in CHT temps of about 45-50°, with #1 the coldest, and #4 the hottest.

Steve Warden

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