Trying to diagnose an alarming knock

Discussion in '6.9L IH & 7.3L IDI Diesels' started by grizzlyjosh, Aug 8, 2018.

  1. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    You appear to have an intake valve issue then, as in one that's not sealing right. If it's loudest there, then that's probably the source of your noise. This would also explain how it can still make the noise with the key off. Sorry for the bad news.
    Maybe in November.
     
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  2. Thewespaul

    Thewespaul Supporting Member Supporting Member

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    I’ll make sure you know my flavor ahead of time;)

    I agree with the intake valve being the issue. As far as what to look for, you may have some guide issues that caused the wear, so you may see soot/carbon buildup around the valve with issues, but you may not.

    Personally I would not run it if you can avoid it.
     
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  3. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    IF you pressed the tube onto a hard surface on the injectors (like the top of the flange of the 1inch part that you put the socket on) or the glow plugs and heard/know the knock was happening but you could not hear it distinctly through the stethoscope then your cylinders are good and it is not an injector knock and most likely if it was rod knock you could hear it there as well. I could hear my injector knock clear as day through the scope once I got to the offending cylinder's injector and the one adjacent to it but could not on any other cylinders.

    Im not very familiar with any of the valve train issues or noises. Youll have to trust these guys on this one if you cant narrow it any further. At least see if you can determine exactly which valve it is and what side its on.
     
    Last edited: Aug 9, 2018
  4. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    i had this problem not so long ago... a week and a half ago infact.
    ended up being a busted rod.
    eliminate fuel.
    eliminate valve train.
    then if its still there, pull the engine

    3F11A7B7-49B9-4FEE-8633-4DF00F5F5E6C.jpeg
     
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  5. grizzlyjosh

    grizzlyjosh Registered User

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    I think that its not an injector/fuel problem because a. the knock continues when I turn off the key in gear while rolling and b. all the injectors sounded about the same with the stethoscope touching the nut part of the injector.
    So valve train...is there a way to 'check' valves without pulling the heads off?
    And is it normal to have condensed water/grey sludge on the inside of the valve covers? Is this a sign of head gasket failure?
     
  6. hesutton

    hesutton The Anti-Anderson Supporting Member

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    You could pull the rockers and may see an issue a little easier, but personally, I'd pull it out and start an autopsy.

    You have grey oil on the dipstick? When you changed the oil last, were there signs of water contamination? Used oil analysis (I've used Blackstone lab) will give a lot of information.

    Heath
     
  7. Knuckledragger

    Knuckledragger blowing chunks

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    This is going to sound nuts, but check your oil level. I had that odd sounding knock when my level was 2+ quarts down. The difference was that it went away off idle.

    I am leaning toward valve problems, but I don't have to do the work to find out. Maybe a failed lifter? Unlike the others, I say drive it till the noise goes away, you get used to it, or the engine quits. Then you will know for sure what it was.
     
  8. nostrokes

    nostrokes Full Access Member

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    You'll have to pull the heads to check the valves... Sorry but that's the way it is.. After you pull the heads you'll be able to check the guides and the valve seats by pulling each valve.

    I have to agree with Wes, if this is your daily or needing to use it for work you need to stop running it until you find the issue. It will get very expensive very quickly if something let's go..
     
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  9. grizzlyjosh

    grizzlyjosh Registered User

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    The oil level is normal and hasn't changed. I just changed the oil a couple of hundred miles ago and didn't notice it being grey or foamy. And it looks normal on the dipstick.
    It is my daily work truck but I have stopped driving it until I figure this out, though I'm running it some to try to diagnose the problem.
    Speaking of, I pulled the turbo off because that was where I could hear the knock most strongly and now when it runs, the knock is less like a knock and sounds almost more like a mini-backfire coming out of the exhaust where the turbo was attached. And I can't hear the knock at all with the stethoscope. The turbo wheel had a bunch of play, by the way.
    So, any thoughts on this? An exhaust caused knock? I'm feeling a little hopeful that the problem might not be too deep but also confused...
     
  10. snicklas

    snicklas 6.0 and Loving It!! Staff Member

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    That sounds like you are describing a chuff. Time to pull the heads, find a GOOD machine shop and have them gone through. Replace valve guides, have them checked for cracks......

    But the most important thing is, since this sounds like it's a chuff. DO NOT RUN THE ENGINE until it's repaired. With it chuffing, it WILL drop valve, so instead of a valve job and the associated seals/gaskets, you more than likely will be replacing the engine.......
     
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  11. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I agree with this one, but have to add that your valve probably isn't going to immediately drop the next time your engine starts. If you need to run it a little bit to get it to some place to pull the engine, you should be ok. Just don't plan on a coast to coast run. The less you run it, the less chance of something catastrophic happening.
     
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  12. grizzlyjosh

    grizzlyjosh Registered User

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    So, I ran it for a while with the passenger side valve cover was off. The rockers and stuff looked normal but there seemed to be blowby coming from...I'm not sure, around the valves? That seems like a bad sign huh? There was also condensation on the undersides of the valve covers...
     
  13. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    the only time i had condensation under the valve covers is when i had a coolant leak inside of the engine
     
  14. lotzagoodstuff

    lotzagoodstuff Supporting Member Supporting Member

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    +1 on the chuff diagnosis.

    Nice job on digging down deep to diagnose the issue.

    There was a really nice video a while back that showed what this condition looks like on a removed head. The valve guide was so warn that the valve could move enough axially around the seat of the valve that you could see it with your eyes.

    If it's a valve moving around that much on the seat, it's only a matter of time before you lose that valve and make a valve job into long block swap.

    Good luck
     
  15. riotwarrior

    riotwarrior Supporting Member Supporting Member

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    Chuff...= Badda boom if u no careful...do not ask me how i know.
     
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