You can make almost any cylinder test within limits by doing a number of things, but you're only fooling yourself. You can ad oil to the cyl and spin the prop. The oil will seal the leaks and instant good compression. I've seen A&Ps rock the prop at TDC (top dead center) to "seat the rings" and get good compression, but it's not a true picture of what's going on. The compression check is to show you any problems and the only way to do it correctly is to bring the cyl to TDC by turning the prop in the normal direction and stop at TDC. If you go by it continue around and do it again. TDC gauges can be bought or made and are easy to use. Then the cylinder will tell you what's happened to it. After all, when you're flying, the engine does not squirt oil in the cyl to ring compression up, nor does it rock the prop to seat the rings. Do your check as in flight conditions and if it shows low, find the problem, don't hide it.
jsilberman
On Apr 9, 2006, at 10:57 PM, [EMAIL PROTECTED] wrote:
<x-tad-bigger>An old timey A&P told me years ago that a really low compression test reading (like less than 60/80) meant that something was definitely wrong; and a really good compression test reading meant that the compression test reading was really good, but really didn't mean much of anything else! I guess your experience agreed with what he was saying. </x-tad-bigger>
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<x-tad-bigger>I also had a mechanic (different guy) tell me that you could usually change a bad compression test to a good test by squirting some 50 weight oil in the spark plug hole and turning the prop over a few times. I think that was the same guy who told me that you could fix a stripped out screw hole in sheet aluminum by sticking a piece of thin safety wire through the hole and then putting the screw in with the wire in the hole.....</x-tad-bigger>
