Annual Compression Tests

[jgpainter2]

I do a compression check each time before I fly. I turn the prop through 12 to 16 times to distribute some oil, and to "feel" any differences in cylinder compression. You really can feel a lower cylinder ! 20 lbs difference is easily noticed. Really ! Also, I do a "regular" compression test at annual after valve adjustment with a "warm" engine. Much easier and safer than a leak down test. If you have one bad cylinder (that you "felt" was bad earlier) you can research further. Remember to convert your readings for your altitude. Charts in Wilson's book or online. George N1020X 2.1 with 175 hrs.

[LarryEWaiex121]

For a really workable tool at a moderate cost, try the OTC leakdown tester. I believe I paid around $75 shipped.
I made the ugly mistake of trying to do a Bob's cheapo Harbor Freight Leakdown tester. It was neither a quality tool nor heavy enough to make a decent boat anchor. It is available for purchase at a special low, low price:)
On a side note. Every leak down doesn't yield the same readings you would expect to see at each test. I have found a cylinder I expected to be really good to be down 6-8 lbs from an earlier test, only to find it back up to normal on a subsequent test. It kind of shows trends or a complete failure.
It's just one tool out of many a guy needs to keep handy to moniter the overall balance of an engine in my opinion.

Larry
Waiex121YX, Jabiru 3300, 449 hrs.

[pfhoeycfi]

What kind of differential compression readings should I expect to see on a new Aerovee (turbo) engine that's only been run for a short time on the ground and to full power only a few times briefly. There might be 30 minutes on the engine at this point.

Peter