Weak hydraulic lifters?

·         Jeff Wilde

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Greetings, I have a 3300 (serial #2223) on a Kitfox 7. It has 110hrs on it now and I really like it. There are two items I would like to ask you about. One, there is a ticking coming from the engine heard at idle, especially with the cowls off. I checked the valve rockers and found 4 of them could be lifted off the head of the valve with moderate pressure on the pushrod side. I checked the day after flying the airplane. The biggest gap was .7mm. The other three were about half of that. Only one was an intake. The maintenance manual says that this is not normal. I found it odd that there were 4 of them. The tapping seems to go away above idle, possibly because of the engine and prop noise but am not sure. Can you give me advice on what to do next. Two, and it may be related to the first, I changed my landing gear over to a taildragger. The angle of the airplane and thus the engine is fairly pronounced. A little steeper than a Sonex. On takeoff it takes about 100 feet to get the tail up. At full throttle, at an angle with the oil sloshed back is it possible for the oil pickup up tube to injest some air? Or, with the oil sloshed back can the crank beat the oil into a froth? If either of these situations could be happening, could this be the reason for the weak lifters, possibly allowing a bit of air into them? Also, if air did get into a couple of lifters, wouldn't running the engine in level flight expel the air? Your thoughts on this are appreciated.

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·         Doug Smith

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Hi Jeff,
A bit of ticking from the engine isn't unusual, though it's one of those subjective things that you need to train your ears for in order to pick what's normal and what isn't. Depending on a few factors I wouldn't automatically see a big problem with the degree of lifter movement you've described. The telling factor there is how the engine performs - if you're making rpm etc. And of course your leak down results etc. So provided everything else is OK I'd just keep an eye on it.
Regarding the taildragger conversion, you should be pretty safe unless the angles are extreme. Did you re-calibrate the dipstick when you did the conversion? The dipstick is set up for the engine sitting pretty much level, so if you're using the engine in a trailsragger you need to drain the sump, then add 3 litres and make a new mark.
Regards,
Doug