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O.S. 46 LA Question

Old 09-09-2002, 11:26 PM
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Default O.S. 46 LA Question

My question is, I'd like to know roughly how long an O.S. 46 LA should last. I understand they are bushing engines, and would depend on fuel, and the care it's given as far as it's life expectancy goes. I run mine with 10%, and I always run out the fuel at the end of the day in order to run the after-run oil in it. I'm looking for number of flights, or hours, or trips to the field. Just a round about number using whatever you want as a measurment.
If it's not too much trouble, I'd also like to know if anyone has had any trouble with the 46 LA within the first few months of owning one that was broken in per the manual, and never crashed. I can't really describe the noise I've been getting lately, but I'm concerned. It's almost as if there's a nut rattling around in the muffler. It's a constant noise with RPM, and seems to maybe get a little louder when throttling down. I've got plenty of power. The same as I've always had from the begining, but this noise really bothers me. I've got it apart right now, and except for the normal discoloration on the head and piston top there is absolutely no sign of wear on this engine, and no sign of metal crumbs, chips, ect.. anywhere. Any help would be appreciated.
Old 09-10-2002, 05:29 PM
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Default O.S. 46 LA Question


The clattering noise you are hearing is normal for a bushing engine. With bushing engines, the crankshaft 'floats' in the bushing. When the engine is under high power, the propeller pulls the crankshaft forward in the bushing. When the engine is at less than full power, the crank can move fore and aft a bit.

What you hear is the crank tapping the crankcase as it floats around.

In a bushing engine, this cannot be avoided. If the crank was shimmed so that it did not have that movement, then it would wind up seizing to the crankcase and you'd have a ruined engine. The noise is just something that has to be lived with in bushing engines.

A more complete explanation of this can be found at:

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