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Who rebuilds Cummins unit injectors?

Discussion in 'Trucks' started by Wes J, Oct 20, 2018.

  1. Wes J

    Wes J Senior Member

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    Got a Cummins L10 that misses and smokes at idle when cold. I'm going to rebuild the STC valve, but I think it's time to do the injectors. It's got 450,000 miles on it.

    Who can rebuild them or exchange me decent rebuilds? These are top stop injectors, PT-D I believe.
     
  2. RZucker

    RZucker Senior Member

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    Check the shift points on the STC first. Also check that the STC tubes aren't leaking at the injector adaptor. If the STC system is not getting oil pressure they will pop and fart on a cold start. Usually the injectors are not at fault.
     
    DMiller likes this.
  3. Wes J

    Wes J Senior Member

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    I dunno. The truck has an obvious miss that brings a cloud of white smoke. It sounds like one, and sometimes two, cylinders are dropping out. The problem goes away when the engine is good and warm. Seems more like an injector issue. Runs great under a load.
     
  4. RZucker

    RZucker Senior Member

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    "Runs Great warmed Up" tells me the injectors are mostly ok, Check out the STC system first, Been there done that with 855 engines.
     
  5. Spud_Monkey

    Spud_Monkey Senior Member

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  6. Truck Shop

    Truck Shop Senior Member

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    With that mileage those top stops are worn out. But like RZ says check the STC system.

    Truck Shop
     
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  7. Wes J

    Wes J Senior Member

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    Still looking for a source. Or am I going to have to buy new?
     
  8. Howey75

    Howey75 Active Member

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    Can the injection place behind Altorfer truck shop help you?Forget the name right now but he’s been super helpful to me in the past
     
  9. thepumpguysc

    thepumpguysc Senior Member

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    Check "Reliance" diesel engine parts..
    I think Cummins has those in remans now..
     
  10. Wes J

    Wes J Senior Member

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    I'll call and find out. He got me some parts for a CAV pump a few years back.
     
  11. Hallback

    Hallback Senior Member

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    Oregon Fuel Injection in Eugene.
     
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  12. Truck Shop

    Truck Shop Senior Member

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    If you need a camshaft you will need to go to Oregon Camshaft they grind one for your locomotive or race car. lol

    Truck Shop
     
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  13. DMiller

    DMiller Senior Member

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    Don't know if the L series had the same issue as the NTs with oil filled injector push rods, when we had old NTs that missed under load the most common culprit beyond an overhead was the injector push rods filling with oil and deflecting under load RPMs.
     
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  14. Wes J

    Wes J Senior Member

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    I spent the whole day messing with this thing today. I installed a rebuild kit on the STC valve, which consists of new o-rings for the spool valve cartridge and a new spring for the spool. The valve itself is dead simple. Just a spool with fuel pressure on one side and a spring on the other. When fuel pressure reaches 23 psi, the spool opens and allows oil to flow to the injectors. I tested the shift point on the bench and it is perfect.

    I did some testing of the STC system before removing it, but it's really hard to interpret the results because the only place to check for oil pressure to the injectors is after a check valve, so the pressure goes up, but it obviously never comes down.

    In my testing I capped off the STC oil line to the injectors and it made no difference in how the truck runs. So, its kind of inconclusive at the point.

    My hunch is that either there is a blockage in the STC manifold to the injectors, or there is an issue with the injectors.

    More to come.
     
  15. RZucker

    RZucker Senior Member

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    You need to check under the rocker cover to see if you have leaks at the injector adaptors. You should have oil pressure at the STC manifold before the fuel pressure hits 23 PSI.
     
  16. Wes J

    Wes J Senior Member

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    Yep. The cover is off. On the list for tomorrow. I did put air to the STC manifold and did not hear any huge leak, but that was before pulling to cover.
     
  17. DMiller

    DMiller Senior Member

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    Hate to inform but was informed by a friend still working in STL, Cummins MO now farms out all mechanical pump/injector work from the STL location. Seems they could not get techs qualified to run the pump room so just shut it all down.
     
  18. Wes J

    Wes J Senior Member

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    I was all set to put the thing back together, but I found that the oil hose from the STC valve to the rocker cover was bad, really bad. I'll have to get one made up tomorrow. I wish I had a hose crimper...
     
  19. Wes J

    Wes J Senior Member

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    I'm not making much headway here. This is what I know:

    The STC valve is working correctly.
    Oil is making it to the injectors
    Oil pressure should be sufficient.

    I did the oil blockage test which involves putting compressed are to the STC manifold and looking for air at each injector. It should leak air around each injector link. 1-4 are fine. But I can't get air at 5 and 6. So, I pulled number 6 injector. The manifold is not blocked. But, the passage under the injector link is plugged solid.

    So, I'm back to the injectors. I went ahead and pulled the cap off the number 6 injector and had a look. Best I can tell it was not machined correctly at the factory and has never been open passage. But, I can't see how that would really hurt much other than oiling the injector link.

    Anywho, I got a quote from Area Deisel for reman injectors. $250 each. I think that's where we are headed.

    I tried Reliance, but they can't get the injectors I need.
     
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  20. petepilot

    petepilot Senior Member

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    wes heres another source for what you need ( randy simpson b&d fuel inj. ) in fredericksburg va. 540-368-1626 call him for a quote on the injectors have dealt with b&d for years` never let me down