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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...

    5,790
    245
    Nov 15, 2009
    AZ
    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 Well-Known Member

    9,831
    109
    Feb 7, 2009
    alaska
    A sheet of glass and some really fine wet or dry will do it.
     
  3. bison

    bison Well-Known Member

    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 Well-Known Member

    7,390
    128
    May 5, 2008
    Castor, AB.
  5. midniteplowboyy

    midniteplowboyy Recruit

    368
    0
    May 5, 2008
    NE, Texas
    What he said.
     
  6. 3500GMC

    3500GMC Stand Your Ground

    4,933
    39
    Jun 7, 2009
    Nashport, Ohio
    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

    2,548
    3
    Nov 26, 2008
    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

    3,212
    2
    May 6, 2008
    Brooklyn, NY USA
    Never heard of that kind of "lapping"..........learn something new everyday!
     
  9. bison

    bison Well-Known Member

    Stick around;)
     
  10. 3500GMC

    3500GMC Stand Your Ground

    4,933
    39
    Jun 7, 2009
    Nashport, Ohio
    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

    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

    2,548
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    Nov 26, 2008
    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

    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

    2,548
    3
    Nov 26, 2008
    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

    4,933
    39
    Jun 7, 2009
    Nashport, Ohio
    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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