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My old 582 stopped one day. It was all singing sweetly before the loud bang. After landing the prop could not be turned all the way around. Here's why.Image Insert:
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Did you check to see if anything was jammed in the water pump or disc valveRuss
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As you can see something happened to the rotary valve. All I found inside the engine were brass shavings that would fit in with the cog damage, otherwise it was pretty clean.Image Insert:
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Dave, Shouldnt the chewed up part be in the center of the gear? Was the shaft or gear somehow allowed to move away from the rotary valve?Flying the right side up in Canada
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Dave, For what its worth I would look for a back and forward pulsing action hammering to have caused that brass gear to have moved on the shaft, in an out of mesh direction towards the spring in the pic.Is that brass gear keyed to prevent it slipping on the shaft? The only cause that comes to mind at this stage is a low idle speed for long durations in time. How many hours on the motor?
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Dave, further to the above post. Had you had the air cleaners off prior to this happening? Reason the rotory valve has 2 score marks on it and so does the finished surface on the block over the 2 ports. To my eye this looks like some small partical of something has picked up between the 2 surfaces. My observations for what they are worth. Good luck, Des
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So is that spring supposed to let the gear slide towards the spring if something jams the rotary valve? Any marks on the piston tops from foriegn debris?Flying the right side up in Canada
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Daveb, the brass gear is designed to be able to float on the shaft to try to take some of the crankshaft hammering away from the shaft and the rotary valve spline. I would be inclined to agree with Des, that the engine has spent considerable time in its roughest mode (low idle), where the sliding brass gear would be at its most active. The brass gear would not be moving against the spring in normal operation, only when the engine is at its extremely roughest. The gearbox chatter is a good guide as to the idle speed of the engine. With a warm engine, bring the idle up until the gearbox chatter just disappears. If this is over 2000rpm then the engine has tune up or other problems.It is normal for the rotory valve and the housing to have scuff marks on them, as long as they are not gouges.Tim McClure
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Looks like a bit of foreign material has found its way to the top of the piston (ring, spark plug or needle bearing). Are the same witness marks on the head?Tim McClure
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Heres the head Tim:-Image Insert:
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I agree with tim (he is a preeety smart fella) looks to me like very small metorite has found its way into your carbie, either that or a small child has decided that the hole in the front of dads motor would be a good place to hide an object. Had it happen and the scars look the same!
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Dave, thats not detonation. That is a foriegn object most likely steel.One little piece can bounce around in there making thousands of little dents. Hard to tell in the picture but is that a couple of needle bearing pieces i see stuck on the piston top?Flying the right side up in Canada
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OK, needle bearing. There are meant to be 31 of these? I count 31 from one piston but only 29 in my other little bag. Don't think I lost 2 when I pulled it all apart. Here's a closeup of the piston.Image Insert:
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A wrist pin needle bearing cannot find its way into the rotary valve drive gear. These are two separate incidents. The rotary valve driven gear may have been like it for some time. Is there any evidence of the missing teeth in the rotary valve drive gear sump?Tim McClure
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