GrummanDude
Joined: 15 Jan 2006 Posts: 926 Location: Auburn, CA
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Posted: Sun Jul 13, 2008 5:29 pm Post subject: Fuel Tank Update |
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I took some pictures of the fuel tank when it was finished. I didn't take any 'Before' pics. Apparently I can make a QuickTime movie with iPhoto. So, I made a movie. I'm not sure where the music came from. I didn't add it. If you want to see the pics, let me know.
OK, so, the next step was to put the wing on and finish the annual. The first step was a compression test. Both cylinders #1 and #3 showed leaking out of the exhaust valve. Since the fuel tank cost the owner about $5000 to fix, I was a little reluctant to call the owner and tell him he had leaking exhaust valves on his 800 hr factory reman engine (reman in 1995).
Ordered two new cylinders. Removed the leaky cylinders. My normal routine is to remove the lifter assemblies and clean them up so I can check dry tappet clearances. Then, coat the cam and lifters with assembly lube. Imagine my surprise when one of the lifter faces felt rough. Flashlight in hand, I found a bad cam lobe and two bad lifters. I mean, really bad. Funny, nothing in the oil filter every time I checked.
I went back through my inspection checklist notes and found my comments on oil changes. Prior to coming to me, the average was an oil change every 50 to 60 hours (there was a maximum of 93 hours at one oil change) using Phillips 20-50 . . . for 7 years. The longest p eriod of time between oil changes was 13 months; at annual. Now, if I'm not mistaken, the Phillips oil does not contain the anti-scuff additive recommended by Lycoming.
Tomorrow, I order another reman from Lycoming.
1. Oil additives wear out.
Technically, oil does not wear out. However, extended use causes an oil’s additives to wear out or become depleted. For example, an ashless dispersant aviation oil is designed to suspend dirt and metal particles picked up from an aircraft engine. Eventually the oil will become "over-suspended." The principal reason oil is changed at regular intervals is to rid the engine of these suspended impurities. Old oil, with a high degree of contaminants, can cause bearing corrosion and deposit buildup. It can also get to the point where it will not suspend the additional particles created during engine operation. This produces particle buildup or sludge. Overworked oil will also result in the depletion of its other additives. The result is that it will be unable to perform with the benefits the additives were designed to provide.
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_________________ Gary
AuCountry Aviation
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