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Do I need injectors/IP?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Quadrunner91, Aug 18, 2019.

  1. Quadrunner91

    Quadrunner91 Registered User

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    The truck is at 280,000mi and has had multiple IPs and injectors over its life time, according to the PO. When I got it it had a bad misfire and smoked like crazy. I replaced the bad injector (Napa) and although better, its still not right. Do I need to invest in Injectors/IP from type4 or am I missing something?

    Both of these videos were taken after a 15-20min warm-up drive. It blows white/blue smoke like crazy above 1500rpm.


     
  2. franklin2

    franklin2 Full Access Member

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    Does it make a weird air noise at the exhaust? Does it use a lot of oil? These engines are notorious for valve guide wear. So bad that the valves will start to not seat causing a miss. Plus lots of oil usage and a hissing noise at the exhaust from the compression leaking by the valves.
     
  3. Macrobb

    Macrobb Full Access Member

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    IP timing is very retarded; the cam likes to stick in the retarded position.
    I tend to get around this by advancing the IP quite a ways - 6 degrees is what it usually takes to get it decent again, which happens to be one IP gear tooth - I'll just pry up the IP gear cover(with everything marked so I know where it was) and then jump the IP gear one tooth clockwise(when looking from the front of the engine). This advances 'base timing' by about 6 degrees, and gets things back into the 'workable' range.

    Replacing the IP is the 'correct' solution; I've just never had the funding to do that handy.

    Also, I disagree on valve guide wear being the problem - I have had an engine with over 1/8" of valve guide wear(due to piston/valve interference) - she still sealed well enough, ran on all 8 cylinders, and didn't produce any smoke despite oil having a fairly large path downwards.

    Also I've had an engine with half the rings cracked, used a quart of oil every 50 miles, .02" of bore taper... it didn't make a ton of power off idle, but ran cleanly(because the timing was correct).
     
  4. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    if you got the cash, do both at the same time!
    turns the truck into a whole different beast.
    ask @morgankshaw
     
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  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Advance the timing a dimes width first and see how it does, but like mentioned previously youre probably due for a replacement pump and injectors. I rebuild and upgrade the pumps to last much longer than the original design by addressing some problematic points such as the advance bore getting accelerated wear from our modern diesel, check it out: https://classicdieseldesigns.com/
     
  6. Quadrunner91

    Quadrunner91 Registered User

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    Okay, thanks guys. I don't have a hissing sound at the exaust, so I guess it's time for injectors and a pump. I appreciate all the info! If anybody has experience with these upgraded injection pumps, I'd love to know the increase in lifespan.
     
  7. renjaminfrankln

    renjaminfrankln Supporting Member Supporting Member

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    you could try injectors first, then IP if that does not clean it up.

    Also worth trying the ATF trick. From what i've read it takes about 100k for a pump to actually wear stuff out. But only a few months of sitting to gum things up.
     
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  8. Quadrunner91

    Quadrunner91 Registered User

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    What's the ATF trick? This truck was sitting for about 6years before I started working on it.
     
  9. renjaminfrankln

    renjaminfrankln Supporting Member Supporting Member

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    Pull the fuel filter and dump out the diesel (better yet start with a new filter).

    Fill it up with ATF. Run the engine for about 2 minutes to allow the ATF to make it into the pump/lines/injectors. Let it sit overnight.

    The ATF will dissolve a lot of gunk and might unstick whatever is stuck.
     
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  10. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    As mentioned before, your timing is very retarded, this usually is caused by two things, advance piston sticking, and the advance bore wearing prematurely due to our really dry modern diesel. You can see if your advance piston is stuck by depressing the arm on the lower driver side of the pump with the engine running. You should hear an audible change in the engine if the timing changes with arm movement. If it doesn’t, your advance piston is stuck, and the atf trick could very well unstick it.

    If it does change the tone of the engine, likely your transfer pressure is just very out of spec, the transfer pressure is what feeds the plungers and controls the hydraulic advance curve in a db2 pump. Transfer pressure drops over time when the pump wears, but the component that affects it the most is the tolerance of the advance piston to the advance piston bore. The piston is a hardened stainless steel slug that slides back and forth in an aluminum bore. This was a solid design back when Diesel was packed full of lubricants and had a high cetane rating when these pumps where design, but with our modern dry diesel these pumps tend to wear out this bore quickly since the stainless piston eats up the aluminum bore without having the necessary lubricant it was originally designed to have. When this bore wears out, transfer pressure is allowed to bypass into the housing of the pump and out the return, instead of pushing fuel into the plungers, and rotating the cam ring to have a proper hydraulic timing curve.

    My solution with all my pumps is to bore out and insert a ceramic sleeve and machine fit it to a new stanadyne (not a chinesium knock off piston) standard sized advance piston. With this ceramic sleeve, I see almost no wear at all after 100k miles, even with our poor quality modern fuels, and have seen much more stable transfer pressures with my customers who run wmo, wvo and biodiesel, even on hot rod pumps making triple stock fuel displacement. It’s not a cheap modification, and it’s reflected in the cost of my pumps, but it’s the only way I have found that these older pumps can truly hold up to modern diesel. I have a customer who is a hot shotter here in Texas, making big power with over 150k miles on his CDD 110cc pump and still no issues, haven’t even had to touch the timing.
     
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