Broke A Rod!!

Discussion in 'Mechanic and Repair' started by hotrodsnapper, Sep 25, 2006.

  1. hotrodsnapper

    hotrodsnapper LawnSite Member
    Posts: 85

    Hey ya'll:
    I forgot to get the model # this morning, I'll post it up tomorrow. I think I let my B&S 15.5 OHV single with pressure lube run out of oil. The rod broke at the fat end and disintegrated, also chewing up the rod journal on the crank.

    I stuck another old engine on the mower, so I'm up and running, but I'd like to try and rebuild this motor as a wintertime project. I have the bottom end opened up, with the crank and rod removed. I did not unseat the rings. Other than having pieces of rod everywhere, the rest of the engine is fine.

    My question is this, should I look at buying a new crankshaft ($$$$ I'm sure), or can I buy a rod with an undersized journal so I could have the existing crank turned? Or is this even worth the effort?

    By the way, this is the first time I opened up a B&S with the spin on filter. There is no "pressure lubrication" that I can tell. The oil pump picks up from the oil pan, and oil is returned to the sump. Nothing even close to the way cars, motorcycles, etc handle oil. I'm not pointing a finger, this is my fault and the best lube system in the world is useless without oil, but I wonder how many folks realize that the pressure lube is nothing more than an oil cleaning system. I wonder if honda, kawi, and kohler are the same.
     
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    if you have to buy a new crank then you'll be better off with a short block. Have you tried cleaning the journal with some emery cloth? Sometimes the journal will take on some aluminum and look wasted only to look new after some polishing.
     
  3. hotrodsnapper

    hotrodsnapper LawnSite Member
    Posts: 85

    I'll take a closer look at it tonight, but I think it was pretty chewed up. I seem to remember that the shiny steel was deeply gouged-leading me to believe that turning would be necessary.
     
  4. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    without the numbers it's a guess but it should have the Briggs "lube power" pump that runs off a gear in the sump. i'll bet the crank will clean up.
     
  5. hotrodsnapper

    hotrodsnapper LawnSite Member
    Posts: 85

    I think I found the model #, it's 28N707-1036 or 28N707-0162. Should I use emory cloth dry or use some kind of rubbing compound. I'm not familiar with its use.
     
  6. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    emery cloth comes in rolls around 1.5 inches wide and maybe 120 grit also called abrasive cloth. it is very aggresive so just use it enough to get the aluminum off the journal. then buy some 400 grit wet dry sand paper and with a little water polish up the journal.
     
  7. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    you do have an oil pump on that unit. Maybe Restrorob will post a picture or go to www.briggsandstratton.com find your parts manual and look at part #1024a
     
  8. hotrodsnapper

    hotrodsnapper LawnSite Member
    Posts: 85

    Yeah, there's an oil pump; I can't see that it does anything other than move the oil through the filter!

    Assuming I can polish the journal, should I replace the rod with a standard size or a .020 undersize rod? Correct me if I'm wrong, I think the journal daimeter is specified at 1.2485 - 1.2493". Here's where that came from:

    http://www.smallenginesuppliers.com...n_specs_single_cylinder_engines_not_intek.pdf


    I'll take a micrometer to the journal after polishing, what's a good minimum diameter to use with the standard size rod?

    Sorry about all the questions, but thanks a lot for the help.
     
  9. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    buy a standard rod. it would take forever to sand it down evenly .020
    yes its a splash lube unit but the oil does get filtered. as long as you clean up the journal the standard rod will work fine. make sure you tear that engine apart to clean all the trash out of it before going back together. let us know how the journal cleans up.
     
  10. hotrodsnapper

    hotrodsnapper LawnSite Member
    Posts: 85

    Will start cleaning the journal tonight, will have to dig through my collection of treasures (my wife calls it all my useless crap) and find some fine sandpaper, or go buy some emory cloth. I'll let you know how it goes.
     

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