Perkins M20

Discussion in 'Diesel Engines' started by chowdan, Jan 15, 2016.

  1. chowdan
    Joined: Jul 2008
    Posts: 102
    Likes: 3, Points: 18, Legacy Rep: 10
    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    Hi everyone,

    I'm in the process of rebuilding my Perkins M20 aboard my '76 Bristol 27. The engine was seized and the pistons are completely frozen solid. I've got the cylinders soaking with ATF/Acetone mixture currently.

    I was wondering if anyone had any tips/insights on how they would pull the engine using the boom and if anyone has any spare parts for this engine they'd be willing to sell?

  2. whitepointer23

    whitepointer23 Previous Member

    I am pulling my perkins out with the boom tomorrow. Will post some pics.
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    When you get it out take the pan off and the crank out.

    The ATF / acetone soak may have done the job well enough that light tapping will free the pistons.

    With luck you can have the cylinders honed , right there on the dock, and simply clean the pistons and install new rings.
  4. whitepointer23

    whitepointer23 Previous Member

    Hello chowdown. I pulled my perkins out today . I have never used the boom as a crane before so i stripped as much as possible off to keep the weight down. But i wouldn't worry again .i will just pull the whole engine and box out together. The short engine didn't even make the boat lean when i swung it out over my runabout. Definitely use a block and tackle though because it gives so much control over the lift. I work on my own so i have to use it anyway. Sorry the pics are sideways. I don't know how to fix it.

    Attached Files:

  5. Lepke
    Joined: Sep 2015
    Posts: 87
    Likes: 6, Points: 8, Legacy Rep: 10
    Location: Oregon to Alaska

    Lepke Junior Member

    Since you have to rebuild the engine anyway... get some acid used for soldering at the hardware store. Put enough in the cylinders to dissolve the rust. If it can get thru the ATF it will foam, eat the rust and pass thru each ring on the way down.
    To break loose the pistons, get a square block of wood and a sledge hammer. Put the block on each piston in turn until it breaks. Make sure the piston isn't at TDC or BDC. I've done this several times. Once with a Volvo gas engine that I put the head back on and ran it for 20 more years.
    The bores could be usable, but may smoke and go thru rings. I don't think your engine is a sleeved engine, so it will have to be bored and either oversize pistons put in or a sleeve. If money is tight and the pistons mic ok and the wrist pins are ok, you could use the originals if you have the sleeve sized to fit the pistons.
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