Michael Burbidge
Well Known Member
Today as I was climbing out my engine seemed to be running rough. It wasn't dramatic, but enough that it got my attention. I was at about 1000 AGL, and still full power when I noticed it. It didn't start then, it's just that my attention had been on takeoff.
It was subtle enough that I had to convince myself that the engine was running rougher than usual.
What finally convinced me was an anomaly in CHT temperatures. My number 4 cylinder always runs colder that the others, but it seemed unusually cool.
I stayed close to the airport and leveled off at about 2500 MSL, and pulled the power back some. When I pulled the power back, the engine seemed to smooth out and the CHT on number 4 gradually climbed while the temp of the other 3 cylinders decreased. This seemed odd to me.
I stayed level at 2500 MSL and after a few minutes went to WOT again. The CHT of 1,2 and 3 climbed, and the CHT of 4 decreased. This definitely doesn't seem normal.
My Engine is a carburated O-320-D3G, one p-mag, one slick.
I don't have much experience with engines, so I'm not sure how to diagnose this. I didn't have the right tools at the hangar to be able to de-cowl and inspect the spark plugs. I will do that tomorrow.
But I'm just wondering if this is normal and what are the possible causes?
Attached is graph of CHT/EGT/MAP. At about 12:10 minutes into the flight is where I was leveled off at 2500 MSL and applied full power. I pulled the power back again at about 13:30, and again applied full power at about 15:18, reduced power again at 17:42.
It was subtle enough that I had to convince myself that the engine was running rougher than usual.
What finally convinced me was an anomaly in CHT temperatures. My number 4 cylinder always runs colder that the others, but it seemed unusually cool.
I stayed close to the airport and leveled off at about 2500 MSL, and pulled the power back some. When I pulled the power back, the engine seemed to smooth out and the CHT on number 4 gradually climbed while the temp of the other 3 cylinders decreased. This seemed odd to me.
I stayed level at 2500 MSL and after a few minutes went to WOT again. The CHT of 1,2 and 3 climbed, and the CHT of 4 decreased. This definitely doesn't seem normal.
My Engine is a carburated O-320-D3G, one p-mag, one slick.
I don't have much experience with engines, so I'm not sure how to diagnose this. I didn't have the right tools at the hangar to be able to de-cowl and inspect the spark plugs. I will do that tomorrow.
But I'm just wondering if this is normal and what are the possible causes?
Attached is graph of CHT/EGT/MAP. At about 12:10 minutes into the flight is where I was leveled off at 2500 MSL and applied full power. I pulled the power back again at about 13:30, and again applied full power at about 15:18, reduced power again at 17:42.
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