Ask Paul: Too much information about our engines?

Q: I have a factory reman Lycoming O-540 E4B5 with 300 hours and 2.5 years on it. At idle (1,000 rpm), my JPI is showing alarms on the #1 EGT for having a large differential — #1 EGT is only 600° while the rest are 1,200-1,300°. Above 1,500 rpm and higher everything seems fine with normal readings and maybe #1 CHT a little lower, but I expect that since it is first in the airstream. I have full data printouts from the JPI.

I have checked the plugs even though my mag checks are fine and replaced the probe on #1 EGT with no change. I’m scared to think I have stuck valves. [Read more...]

The marriage between piston rings and cylinder wall

Q: I am an A&P, and have been in aviation since 1990. I once worked with another mechanic who told me that if you pull a piston out of a cylinder, you must replace the rings and hone the cylinder. He is the only tech I have heard say this — until I read your article What’s best? A flush or overhaul?

You stated: “If oil starvation is suspected, you may want to remove the #1 cylinder (leave the piston in the cylinder so you don’t have to hone the cylinder and install new rings) and remove the connecting rod from the crankshaft.” Can you explain this? Is there a Service Bulletin or other directive that explains this practice? Thanks for sharing your knowledge with us.

TOM THROSSEL, via email

[Read more...]

Will this replacement camshaft work in my engine?

Q: I have an O-290-D2 that I am going to use in an Experimental Wag Aero 2+2 that I am building. Although the engine was flying regularly before I removed it from a Pacer and pickled it, I want to open it up to look at the cam. If the cam is pitted, a replacement will be difficult or prohibitively expensive.

[Read more...]

Ask Paul: What causes this popping sound?

Q: I am test flying my new RV-9. It has a new Superior O-320, dual p-mags and an MTV11 2-blade MT prop. When it has been running at cruise power for a few minutes or more (say 2,300 rpm x 23 inches or more) and then I reduce the throttle, I get a popping/crackling sound from the engine. If I reduce the rmp before pulling the throttle, it doesn’t seem to do it so much. This typically happens when joining downwind to land, but other times too if I pull the throttle.

[Read more...]

Ask Paul: What’s best? A flush or overhaul?

Q: I recently found paper towel bits and pieces in a Lycoming engine in an aerobatic airplane. The pilot said he saw the oil pressure go to “zero,” so he reduced power, and landed safely. Would you suggest a flush or overhaul? What’s the best way to go about this?

ED NELSON, via email

[Read more...]

Ask Paul: Why is my spark plug oil-fouled?

Q: I have been noticing an intermittent miss on the left mag during mag checks on the O-235L2C in my 1981 Cessna 152 (about 670 SMOH that included new Lycoming cylinders and pistons). About 30 hours ago when I cleaned, regapped, and rotated the plugs, I found that the lower plug on the #4 cylinder was filled with oil around the inner electrode and ceramic insulator. [Read more...]

Ask Paul: Tips to getting Dad’s Pacer flying again

Q: I was reading your explanation on the difference between narrow deck and wide deck Lycomings — what an excellent piece of writing. My interest is that my brother Lee and I have my Dad’s PA-20 and, while stored indoors, it hasn’t flown since 1964 or so, but I’m thinking (perhaps foolishly) about putting it back together. I’m thinking the old O-290-D-2 (while in excellent shape and only 200 TT, but 7/16ths valves) will have to go. An O-320 is approved in the Wag Aero and Copper River STCs for the PA-20 (so is a 160 by another company). I don’t know why the O-320 works out so well in the Pacers, it’s only another 15 hp.

The big question is that I have found several narrow deck O-320s for sale and wondered if that engine is any more or less worthwhile than the wide deck version. [Read more...]

Ask Paul: What’s the proper procedure to cycle a prop?

Q: I’m curious about the procedure for cycling a constant speed propeller on run up. Three times seems to be a tradition, but I can’t find anything that supports this as a good habit. [Read more...]

Troubleshooting a rough-running engine

Q: My Lycoming TIO-540 engine on my Cessna T206H is running very rough at max power setting. I recently replaced one dud cylinder due to very low compression. The ring gaps were wide and exhaust valve guide and seat were bad. Presently all compressions are good, ignition timing is good, and turbo giving boost. The prop looks OK. The engine has TT of 375 hours. The plane is AOG in a remote location. Any ideas?

COLIN WARD, via email

[Read more...]

Ask Paul: Should you lean for a sea-level takeoff?

Q: At or around sea level in a non-turbo airplane, like a 152 or a 172, should you lean your air fuel mixture for takeoff?

[Read more...]