Ask Paul: Too much information about our engines?

Posted on July 1st, 2012 by

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... Continue Reading →


The marriage between piston rings and cylinder wall

Posted on June 3rd, 2012 by

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.... Continue Reading →


Ask Paul: What is the correct timing for my engine?

Posted on May 8th, 2012 by

Q: I have a Lycoming IO-360-A1A on a Mooney E model. My mechanic tells me that there are two timing settings for this engine: 20° and 25° BTC. The engine had been set at 20° BTC and he reset it... Continue Reading →

Will this replacement camshaft work in my engine?

Posted on April 8th, 2012 by

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... Continue Reading →

Ask Paul: What causes this popping sound?

Posted on March 6th, 2012 by

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... Continue Reading →

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

Posted on February 13th, 2012 by

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... Continue Reading →

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

Posted on January 25th, 2012 by

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,... Continue Reading →

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

Posted on November 28th, 2011 by

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,... Continue Reading →

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

Posted on November 13th, 2011 by

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. Continue Reading →

Troubleshooting a rough-running engine

Posted on October 2nd, 2011 by

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... Continue Reading →