pinerunner Posted December 25, 2013 Report Posted December 25, 2013 MB made a telling observation in one of his vids. If you browse Trade a Plane there are lots of ads with both a SMOH listed and also a recent "since top overhaul" as well. A lot of valve problems? What's the experience you guys have been having, or observing in others. Especially with our Lycoming 4-bangers. Does LOP seem to cure, Camguard, just fly it a lot? Is there any worst thing that seems to lead to needing a top overhaul soon? I've only had mine two years so I haven't got there yet. But even though it has a factory new IO-360 with 1300 hours, the logbook shows that at 800 hours it was torn down and so much done that they might as well have gone on and done a major.
aaronk25 Posted December 25, 2013 Report Posted December 25, 2013 This is interesting to me as I operate LOP and run camguard but have been slowly overhauling cylinders because valve guides have been wearing and it hasn't resulted in any "morning sickness" just all off a sudden increased oil consumption. I'm at 1,600 hours on the cylinders and the last issue was the #2 intake valve guide which seemed weird that it would need attention as that is my coolest running cylinder at 310-330 degrees but according to popular grove engine shop the issue wasn't operated induced but actually a manufacturing flaw as the rocker arm was misaligned and side loaded the valve guide at the top which accelerated the wear and drove up oil consumption up from a quart in 7 hours to a quart in 2.5hours. So with that issue fixed oil consumption went back to norm, but lately it's been creating towards a quart in 4 hours up and my borescope is showing a ring of oil around the #4 exhaust valve guide. So I'm not burning valves but I am wearing out valve guides. But I REFUSE to pull off a cylinder that is making full rated power just because a valve guide is passing some oil. I know what I got and the unknown variables such as incorrect installation or putting a new untested cylinder assembly on concerns me more than adding a few more quarts of oil between oil changes. Besides as soon as I replace a cylinder I start wearing out the new parts!
Steve65E-NC Posted December 25, 2013 Report Posted December 25, 2013 Many of the top overhauls out there came out of the Chermichrome fiasco. I had my engine rebuilt in about 92 with a pricy port and balance cylinder overhaul. The first Chermichrome cylinder failed badly on compression within about 400 hours. All had been replaced with Cherminil (yes ECI helped a little on price of parts) by 800 hours. Of course extra money for Port and Balance was wasted. Now at ninteen hundred since overhaul and now Eleven hundred hours since last cylinder replacement, I have had no particular problems with the Cherminil. Many claim that the IOs automatically need a top around 1000 hours and that may be so, but if Chermichrome was involved that alone will explain the top overhaul history.
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