Can a member help me with lapping leaky injectors?

Discussion in 'GM 6.5 Diesel Engines' started by WarWagon, Jul 16, 2011.

  1. WarWagon

    WarWagon Well it hits on 7 of 8...

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    I don't have the tools to mess with injectors and the local shop is just costing me money without standing behind their work. I now have 2 leaking body injectors from them. They pump them up on the stand without the return lines and can't see the leak because the return fuel coats the injectors... :mad2:

    So shop recommendations or a member that can correct this by lapping them would be helpful.
     
  2. ak diesel driver

    ak diesel driver Active Member

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    A sheet of glass and some really fine wet or dry will do it.
     
  3. bison

    bison Active Member

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    I use a sheet of glass with a sheet of crocus cloth on top.use diesel as lub and swirl the parts in a figure 8 patern.
     
  4. NVW

    NVW Active Member

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  5. midniteplowboyy

    midniteplowboyy Recruit

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    What he said.
     
  6. 3500GMC

    3500GMC Stand Your Ground

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    X3.. Used wet or dry sand paper 600 to 1200 to 2000 grits. Took some time, be patient. Lap both sides of the cup washer in there too.

    The piece with the two holes- photo.

    DSC01713.jpg
     
  7. bk95td

    bk95td 6.5 nut job/addict

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    The pop tester can't produce the pressure and volume that the ip does on a running engine. The pop tester only goes to the pop pressure. The ip can be running 4000 psi or more.
    I use 1000 grit wet or dry sandpaper on a piece of glass with diesel fuel for lube.
     
  8. Brooklyn Tow

    Brooklyn Tow 9 11 Never Forget

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    Never heard of that kind of "lapping"..........learn something new everyday!
     
  9. bison

    bison Active Member

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    Stick around;)
     
  10. 3500GMC

    3500GMC Stand Your Ground

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    Post #6 said the 'the piece with the two holes'... Should have read, 'the piece with the three holes'... You know what I meant.
     
  11. buddy

    buddy New Member

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    So the injectors are actually leaking out of the threaded body part? Something is not sealing the high pressure away from this area like it normally should?
     
  12. bk95td

    bk95td 6.5 nut job/addict

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    There is no actual seal. It is metal on metal. The surfaces are ground "flat". "Flat" is a relative term. "flat" could be + or - .05 or .005. The surfaces distort over time especially with all the heat cycling. The sanding them trues the surface enough to make a seal again.
     
  13. buddy

    buddy New Member

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    Although, would fuel normally be in the area of the threads to make its way to the return nipples? Or would that normally spit out above the threads? Does fuel spill around the outisde of the nozzles normally to cool them in operation? I am just wondering if its normal to have fuel in that area, and if there is any other explanation. Should the body have some thread sealer and torqued to a specific value?
     
  14. bk95td

    bk95td 6.5 nut job/addict

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    No thread sealer. Torque spec is 65 ft. lbs. There should be no fuel get to the threads if the surfaces are lapped close enough. I would imagine that the return fuel does somewhat cool the nozzle but the fuel is really not all that cool after being pumped to a high pressure.
     
  15. 3500GMC

    3500GMC Stand Your Ground

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    Total metal on metal seal, yes. Thats why we take our time with the lapping process.

    In the pic, these are the parts that are totally responsible for sealing up FUEL inside the injector. Note the small hole in the inj TOP. This is where the main pressurized fuel flows. On up in the injector TOP there is the return passages.

    Also, using a sealer on the threads would be asking for trouble. It simply isn't needed.

    DSC02569.jpg
     

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