Misbehaving cylinder during run up - any ideas?

kaiser

kaiser

Pattern Altitude
Joined
Mar 6, 2019
Messages
2,241
Location
Chicagoland
Display Name
Display name:
The pilot formerly known as Cool Beard Guy
I bailed on a trip today due to several issues with a rental, the worst of which was some engine symptoms. I forgot to video it, but I’ll try to recall all of the facts. I had my family with me (I’m very conservative with them) and let’s be honest, there’s only so much troubleshooting I’m going to do when being billed $$$ Hobbs. I wanted this to be a learning experience, so I’m interested in what my PoA brethren think.

The plane is a 1997 Piper Saratoga SP (P32R-301) with the IO-540-K1G5D. It’s an April-annual plane and about 50 hours to the next 100-hr.

Startup and taxi were normal. Oil temp/pressure in the green. Run up @ 2000 rpm. When checking the right mags, I get big vibrations, clunking noise, and cyl 6 reads cold (700ish). Bringing both mags back online and leaning (thinking it could be carbon build up) doesn’t solve the problem. What really caught my attention other than the clunking is after leaning out with mags both, I get an un-commanded jump in RPMs to 2100 (greater than 100rpms at that time). I cycle through checks and mixture for a bit. The issue was consistent. I concluded that #6 is at best intermittent and I wasn’t able to operate it to my satisfaction. On taxi back (~1000-1100 rpm) vibrations settled and I think heat came back to the cylinder, perhaps even normal combustion? I put 0.4 on the plane so I suspect I was messing with the engine for at least 10-15 minutes.
 
kaiser said:
I bailed on a trip today due to several issues with a rental, the worst of which was some engine symptoms. I forgot to video it, but I’ll try to recall all of the facts. I had my family with me (I’m very conservative with them) and let’s be honest, there’s only so much troubleshooting I’m going to do when being billed $$$ Hobbs. I wanted this to be a learning experience, so I’m interested in what my PoA brethren think.

The plane is a 1997 Piper Saratoga SP (P32R-301) with the IO-540-K1G5D. It’s an April-annual plane and about 50 hours to the next 100-hr.

Startup and taxi were normal. Oil temp/pressure in the green. Run up @ 2000 rpm. When checking the right mags, I get big vibrations, clunking noise, and cyl 6 reads cold (700ish). Bringing both mags back online and leaning (thinking it could be carbon build up) doesn’t solve the problem. What really caught my attention other than the clunking is after leaning out with mags both, I get an un-commanded jump in RPMs to 2100 (greater than 100rpms at that time). I cycle through checks and mixture for a bit. The issue was consistent. I concluded that #6 is at best intermittent and I wasn’t able to operate it to my satisfaction. On taxi back (~1000-1100 rpm) vibrations settled and I think heat came back to the cylinder, perhaps even normal combustion? I put 0.4 on the plane so I suspect I was messing with the engine for at least 10-15 minutes.
Click to expand...
Typical of a failed or totally fouled plug. The clunking is likely unburnt gases from the dead cylinder popping off in the exhaust. The jump to 2100 on leaning is fairly normal. AT higher power settings, the mix is rich, and leaning will bring the mix toward best power.

That rental should cost you nothing. No ethical FBO should be charging you for time in a defective, unairworthy airplane.
 
Sorry for the issue but I’m really glad you described the type aircraft and engine.
 
Dan Thomas said:
...That rental should cost you nothing. No ethical FBO should be charging you for time in a defective, unairworthy airplane.
Click to expand...

Yea, you rented the aircraft to go somewhere, not play with it or troubleshoot it for half an hour. Get your money back or get a credit.
 
the plane flew yesterday evening, so it must have been resolved. Autopilot/elec trim was over loading the circuit breaker too so hopefully that was also fixed. I’ll grab the plane next week again for a few landings.
 
You wouldn't have all these problems if that bird had a proper Johnson bar.

Just sayin'
 
kaiser said:
the plane flew yesterday evening, so it must have been resolved. Autopilot/elec trim was over loading the circuit breaker too so hopefully that was also fixed. I’ll grab the plane next week again for a few landings.
Click to expand...

Did they charge you? If you didn’t take off should be no fee, or check the POH for start&taxi fuel usage and cover that couple gallons at the most.
 
Jim K said:
You wouldn't have all these problems if that bird had a proper Johnson bar.

Just sayin'
Click to expand...
Which airplane uses a Johnson bar for autopilot and trim?
 
Sorry all, haven’t flown that bird yet. I’m hoping to get back in it this weekend. I did spy on FlightAware that it’s flown and is not a smoking hole somewhere. I’ll provide an update when I fly it. I’m also hoping they fixed the elec trim too.


Dan Thomas said:
Which airplane uses a Johnson bar for autopilot and trim?
Click to expand...
What you have to understand is that @Jim K only respects aircraft with Johnson Bar flaps. Most of the worlds problems are because we went to electric flaps ;)
 
I flew it today. Electric trim is still inop. Everything else works. Engine purrs like a tiger. It was light and cooler today so I had fun climbing at 1500+ fpm… worlds apart from the C170 I’ve been flying.

No news from the owner what it was, if anything.
 
Dan Thomas said:
Typical of a failed or totally fouled plug. The clunking is likely unburnt gases from the dead cylinder popping off in the exhaust. The jump to 2100 on leaning is fairly normal. AT higher power settings, the mix is rich, and leaning will bring the mix toward best power.

That rental should cost you nothing. No ethical FBO should be charging you for time in a defective, unairworthy airplane.
Click to expand...
ha.. you said “ethical” and “fbo” in the same sentenced…
 
You must log in or register to reply here.
Back
Top