Engine Decarboning: Reassembling the Cylinders, part 1
WARNING: The author of this page is not a professional or certified aircraft engine mechanic. The information contained herein constitutes a description of the writer's experience only and should not be construed or interpreted by the reader as instructions or guidance for the successful completion of any repair or maintenance procedure. Use of any information contained herein is at the user's own risk. This information has not been reviewed, evaluated, or approved by the manufacturer of this engine.
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In preparation for cylinder reassembly the wrist pin needle bearings should be lightly lubricated with two-cycle oil. Not a lot, just enough to wick in between the needles.
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Likewise the bore of the cylinders should be given a light coating of oil. Again, not a lot; this oil is just to lubricate the rings as they reenter the cylinder and so the engine won't be dry when it starts up again. |
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Make sure the gasket sealing surface of the crankcase is clean and dry and install a new cylinder base gasket. Work it carefully down the cylinder bolts a little at a time keeping it flat and being careful not to crimp or tear it especially at the narrow parts. Then lower the piston on wood blocks centered under the cylinder just as you did at disasssembly.
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Ring installation is the reverse of disassembly. Make sure you've got the same rings that were on the piston you're working on. The lower ring goes on first. Check the microscopic letters or the mark you made to make sure it goes on the same side up that it originally was. If using a ring spreader, open the ring just enough to lower the ring into it's groove on the side opposite the ring gap and locating pin in the ring groove. It doesn't have to be in it's groove all the way around yet. Release the ring then carefully work the ends of the ring apart and down till the ring is in the groove and the gap is at the locator pin. |
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The top ring goes on without tools just by placing one end against the locator pin and working the ring around the piston and into it's groove. Make a final check that rings are totally free and loose. Check everything to make sure everything is where it should be (both circlips replaced?) and that you haven't left any of your surgical tools inside the patient. You're about to close it up. |