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Cleaning up a rusty old lump

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  • Cleaning up a rusty old lump

    A customer has a canal Narrow Boat with an old Bolinders semi-diesel, single cylinder direct reversing 2-stroke.
    He's had a problem with water getting into the cylinder and crankcase. Turned out to be the cylinder wall had corroded through from the outside.
    We looked into various repair methods, but decided all would be expensive and all would carry a risk of failure.
    Eventually he located a spare block. Trouble was, it had been in a fire, building burned down, 40 years ago and had been kicking around in somebody's garden ever since.
    There was a major stroke of luck, in that this block had a standard bore, 190mm or about 7.5", while his existing cylinder had been bored 1.5mm oversize and had the piston to match.
    I tried a flap wheel on the rusty bore in a couple of spots & decided we were in with a chance.
    Took it to my friendly reconditioners, they were very doubtful but gave it a go and it did in fact clean up (honed out) very nicely at the new size.
    After that it was down to me. This thing is about 170 lbs, the bore is about 19" long.



    I had turned some aluminium Pie jaws to fit the bore & hold it to the lathe spindle:-



    The tailstock end was supported with a rotary chuck. I was disappointed to find that mine wouldn't quite open big enough, so had to resort to using that chuck to hold another:-



    This also shows the sorry state of the top joint faces, the first job was to get these back to something decent:-



    More in our next...

  • #2
    That is certainly utilising all the capacity of that lathe and then some!, i think i would have been tempted to get it on a bigger machine myself lol, well done even if you have to wipe your rear end with a Q tip!
    Mark

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    • #3
      For some reason, these engines used a stepped joint, an inner ring to seal the cylinder pressures and a perforated gasket on a different level to seal the water spaces.
      The depth of the step had to be maintained, measured from the 'old' block because there was nothing to measure from on this one:-



      Then the top of the bore is chamfered, to help with fitting the piston with rings, this had to be opened out/cleaned up.

      Next there was a frost crack in the water jacket to be dealt with. Decided to have a go at stitching it myself, though maybe not by the 'approved' methods.
      I decided to use the lathe as a positioner for the rest of the jobs, copuld easily rotate it to the best position and lock it securely.

      First drilled & tapped a hole 2BA at either end of the crack, to hopefully stop it spreading. Then a series of intermediate 4BA screws, tapped & sealed with Loctite retainer, which should also add a little tensile strength:-



      These were cut off when set, and intermediate screws fitted, continuing the process until the whole crack was filled:-



      Incidentally the sole reason for using BA screws was that they were what I had, in the right sort of size, in plain mild steel.

      Then there were a series of screws and studs into the block which were not willing to come out, 40 years of rust had set them solid & they simply sheared off so had to be drilled & tapped out.

      Next a couple of coats of paint:-



      I had to check the length and compare it with the other block, it was 2mm shorter, so I've made two gaskets each 1.5mm thick to go between cylinder block and crankcase to bring the top back to roughly the right height. These are not high precision machines, but in the absence of any proper data I reckoned that it's best to keep the piston height close to what it was before.

      Now I just need to clean up the piston and reassemble the engine, then make it go again. Should be Friday's job, it's not at my place so have to travel.

      Tim
      Last edited by Timleech; 04-09-2014, 06:32 PM.

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      • #4
        Originally posted by boslab View Post
        That is certainly utilising all the capacity of that lathe and then some!, i think i would have been tempted to get it on a bigger machine myself lol, well done even if you have to wipe your rear end with a Q tip!
        Mark
        Nah, loads of room! It's a 19" lathe, that thing is no more than 14" overall (he says, without measuring it)

        Tim

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        • #5
          Timleech, thanks for the very interesting pics and posting.

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          • #6
            A video of it running would be a treat. Those old one-lungers have such a distinctive sound.

            doug

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            • #7
              Originally posted by michigan doug View Post
              A video of it running would be a treat. Those old one-lungers have such a distinctive sound.

              doug
              The owner is having fuel troubles with it, which he is hoping to resolve himself, otherwise I might be a able to oblige. It's been running, a few times, but not reliably yet.
              They have a hit-and-miss governor, whihc does give them a distinctive sound, as well as a neat reversing system, the basis of which is to spray fuel in early enough for the piston to bounce back & run the other way.

              This is the actual boat & engine, before their troubles:-
              http://youtu.be/s-4DmpLrXvM

              Here is a rather fuzzy video of the reversing mechanism on a similar engine. The main fuel pump is the horizontal one, the vertical one with the external spring is the reversing pump:-
              http://youtu.be/VZHbnUyjD4c

              Tim

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