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Old 06-01-2011, 10:23 PM
jusjofok jusjofok is offline
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Join Date: May 2011
Location: Kansas
Posts: 13
Default 127 Knock after rebuild

Hello guys, new to the forum here. I have a 127 with 42" mower, tiller, front blade and back blade. Have owned it for a few months now.

When I first got this mower I noticed the engine made a rattling noise and it progressively got worse. This not being my first rodeo with Kohler engines I figured it was the balance gears if they were still installed. I tear the engine (K301) down and find the balance gears both about to let go, the snap rings were about 3/4 worn through and they wobbled like a 40 year old push mower wheel. While I was there I noticed the piston had quite a bit of play and the rod had some galling in it. I had the crank turned .010 and the cylinder bored to .030 over (it had a .020 piston in it) by a reputable machine shop. I purchased a new piston and rod from Stens as I have had good luck with their parts in the past and threw it back together. Cranked it up and it was quiet as a mouse. I started to mow my yard with it and about 15 minutes into it I started noticing a knock again. It doesn't do it under heavy load but when you back off the throttle from revving it, it rattles down to an idle (just like I have always heard a bad rod sound). This is the first one I have put back together without checking all clearances on the machined parts first. Changing timing doesn't help this thing and I can hear the knock with a screwdriver all over the engine.
Will the PTO basket make a noise that sounds identical to a rod knock or is that just my wishful thinking? Cam play was about .023 when I took it apart and I shimmed it down to .005. Valve clearances are good and there is very little play in the guides, no bubbles through WD-40 with a blow gun on the port side.
Another thing, it had quite a bit of blowby even after 45 minutes of pulling and was extremely hot, I couldn't touch the points cover for over a second. Any ideas what is going on?
Justin