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Hot!31c707 0154e1 engine

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Red Beard
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2020/11/08 16:58:58 (permalink)
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31c707 0154e1 engine

Craftsman yt 3000

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    Red Beard
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    Re: 31c707 0154e1 engine 2020/11/08 17:03:11 (permalink)
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    I’m having significant oil blow out the exhaust. Head gasket was fine. Replaced the head gasket and intake valve rod seal a year ago. It seems the cylinder rings are the culprit but what’s odd is had no smoke when I used it last and then next start it smoked like crazy and idled really rough. The quick difference made me think it was a gasket but there is quite a bit of oil in the cylinder, maybe a 1/2 a teaspoon. No gouges or really and marks in the sleeve either. 🤷‍♂️
    Red Beard
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    Re: 31c707 0154e1 engine 2020/11/08 17:05:12 (permalink)
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    Again the gasket shows no sign of blow out, last time (1 yr ago) I did the dirty and put permeated on the gasket and it seemed to work. Thoughts on what else could cause the smoking?
    AVB
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    Re: 31c707 0154e1 engine 2020/11/08 17:37:05 (permalink)
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    Wish you did a leak down test before pulling the head. Also have you checked the oil level?
    Red Beard
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    Re: 31c707 0154e1 engine 2020/11/08 20:09:13 (permalink)
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    Haven’t heard of that test, bummer. Going off of my 76 year old neighbor knowledge. Oil level was a lil high when it happened but I had changed it a week before and had mowed half of my 2 acres w no issue.
    Red Beard
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    Re: 31c707 0154e1 engine 2020/11/08 20:21:00 (permalink)
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    So the full story is this. Changed the oil a week ago and mowed my front lawn.Did 2 laps around the back and my transmission front mount bracket (torque strap) broke and bc of life w 4 kids and issues w parts being delivered, the lawn mower sat out there for 1 1/2 weeks. Rained a couple of days in there. Got the part, pushed the lawn mower into the garage and replaced it w no issues. Started it up w no smoke or issues and parked it in the shed. I pulled it out to clean out the shed and parked it. Went to put it back in but wouldn’t start, seemed the battery was dead so I put the trickle charger on it over night. Now my lawn mower has this refurbished engine in it and the guy who did it put in an inline fuel shut off bc the carb float didn’t work I guess. So ended up it wasn’t the battery, I had left the shut off in the on position and gas gravity fed down and flooded the cylinder which then locked it up from turning over( it’s happened like 5x in the 3yrs I’ve had it) so it had gas sitting in there for a day. Figured that out, pulled the plug, cranked it to blow out the gas, reinstalled the plug(which also looked great). Started right up but had the thick oil smoke immediately, let it run like that thinking it just had some residual gas/oil to burn off. It got a little better but still spewing smoke and sounded really rough. Btw w the piston head about 1/2” back from tdc I was able to rock the piston head back forth a little bit, seemed like way too much play in the rings but I have little knowledge on clearances on these small engines.
    Sorry for the lengthy story, thanks for your patience!
    Red Beard
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    Re: 31c707 0154e1 engine 2020/11/08 20:22:10 (permalink)
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    Again absolutely no smoke before starting up that last time, and the head gasket I’m sure was not the issue.
    Roy
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    Re: 31c707 0154e1 engine 2020/11/08 21:48:42 (permalink)
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    With the cylinder flooded the crankcase will be as well. Change the oil.
    AVB
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    Re: 31c707 0154e1 engine 2020/11/09 08:15:21 (permalink)
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    Lets see there is three different possible carburetors on that engine. Now if it is the Nikki they do develop fuel leakage over time as the o-rings shrink and harden.The other two does develop leaks to over time just as quick as the Nikki. Pressure testing the carburetor inverted is how to test for this problem as they all must must hold 5 psi to 10 psi without any leakage for at least 30 minutes.
     
    Putting an inline fuel doesn't fix the problem; just masks it. An automatic fuel valve is a lot better than those manual types as operator doesn't forget to turn it off. The problem is most techs don't know about them.
     
    As for the standard cylinder specs. IF hone to .020" (.5 mm) over add .020" (.5 mm)to the following:
    Bore Diameter 3.563 in. (90.50 mm) Reject 3.567 in. (90.60 mm)
    except the following is the same for either.
    Bore Out-Of-Round Reject .0015 in. (.04 mm)
     
    Piston rings end gap and piston landings specs:
    Ring End Gap (Top) .006-.009 in. (.15-.23 mm) Reject .030 in. (.76 mm)
    Ring End Gap (Middle) .014-.018 in. (.35-.45 mm) Reject .030 in. (.76 mm)
    Ring End Gap (Oil Control) .006-.010 in. (.15-.25 mm) Reject .030 in. (.76 mm)
    Ring Land Clearance (Top) .002-.005 in. (.05-.12 mm) Reject .007 in. (.18 mm)
    Ring Land Clearance (Middle) .002-.005 in. (.05-.12 mm) Reject .007 in. (.18 mm)
    Ring Land Clearance (Oil Control) .002-.005 in. (.05-.12 mm) Reject .007 in. (.18 mm)
     
    These must measured with the piston out of the cylinder. Rings are measured inserted at half down the stroke.
     
     
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