Piston slap...if you have grooves in the upper part of your cylinders then you may have some slapping going on. Over time, cylinder walls develop a taper to them. If it gets pronounced then the pistons literally start slapping around in them.
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02:05 PM
1fatcat Member
Posts: 1519 From: Zimmerman, Mn Registered: Dec 2010
I haven't seen this personally, but a seasoned tech that I used to work with told me the iron duke liked to take out the front piston first. He said it was due to the cooling system cooling the first cylinder more than the other three. The piston would heat up, but the cylinder stayed cooler for a while longer and caused the piston to cylinder wall clearance to diminish (causing scuffing). After running long enough, the cylinder would heat up to opperating temp and the clearance would return.
A compression test should show a loose piston, but it sounds like the engine is too far apart to do any proper testing right now. Other than a complete tear down and inspection, I don't know what to suggest? To do any testing, you would have to reassemble everything...just to take it back apart after finding test results. At this point, I say tear it down and inspect everything.
