dented pistons

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  • wedgie


    Replies: 1041
    Topics: 78
    #3511

    Hi all

    Picked up a seized QD 18 today. I looked through the plug holes and noticed both pistons were dented by a p/o trying to free it up by pounding on them with a blunt instrument. Well, I pulled the head (only broke one bolt) and managed to free it up by liberal use of some seafoam deep creep and a 2×2 piece of wood for a drift. My question is: does the damage to the piston necessitate replacing them ? They are not broken through, but are dented about a 16th of an inch. will the dents create hot /cold spots ?


    Anonymous

    Replies: 67
    Topics: 0
    #31015

    I would just smooth the sharp edges so as not to have a hot spot.


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #31030

    Use ’em. But how is the rest of the powerhed–rings, bearings, etc?


    billw

    US Member - 2 Years
    Replies: 2071
    Topics: 66
    #31032

    Me too. The fate of the world doesn’t usually depend on our motors. Not usually a life and death situation. The pistons will probably be fine for a few runs, now and then, by a hobbiest. However, my experience with stuck QDs and FDs has often shown that you’ll also have rust damage on the crank. Have you seen it yet? To me, that would be more worrisome than the pistons….

    Long live American manufacturing!


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #31036

    Hmmmm.
    How about the wrist pins, are they sloppy? I am guessing this is why the pistons are dented.
    Oh, OK, just reread the post.
    The previous owner dented the pistons with a punch trying to free them up, correct?
    If so, I wouldn’t worry about it, maybe just try to smooth the ridges down with some emery.
    But, you still want to check for sloppy wrist pins.


    wedgie


    Replies: 1041
    Topics: 78
    #31037

    I haven’t opened it up yet, but there was a small amount of rust apparent in the cylinders. There is some slop too, but I’ve seen worse. I will clean up the head and gasket and put it back on to see what kind of compression there is. If it’s no good, that’s ok ’cause there are lots of good usable parts including a really nice cowl and emblem,a good prop that I need for another QD hanging on the rack . I haven’t checked the gearcase yet , but it spins freely and looks good on the outside with no breakage. Got it cheap too 🙂 !


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #31043

    Good plan, I’m sure it will clean up and have decent compression, and run great too. Remember, those QDs don’t have a lot of compression…


    wedgie


    Replies: 1041
    Topics: 78
    #31050

    Compression is low, under 50 psi on both, and as was suspected there is rust in the crankcase. No big surprise as I have seen that a few times on the QD’s as well. I will pull it apart completely tomorrow to see just how bad it is, but for now, a view into the intake:


    chris-p


    Replies: 2456
    Topics: 153
    #31058

    Ewwww, you can see why the motor was stuck. That one will have to be opened up.


    Mumbles


    Replies: 5764
    Topics: 298
    #31078

    Need a crank? I think I have a few usable ones.

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