7.3 IDI Turbo Knock -> Engine Pull and Rebuild

Discussion in '6.9L IH & 7.3L IDI Diesels' started by MICHAEL MICHAUD, Aug 11, 2018.

  1. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    I bought this truck, the blow by was normal, all the fluids were clean and normal, the truck ran and drove without issues. I used it to tow my car on a uhaul trailer5 hours home and about half way through the trip I could hear the engine knocking. Using a stethoscope I listened to each cylinder and I can hear the knocking distinctly from the #7 and slightly from the #5 cylinder. When I crack the #7 injector line the knock goes away.

    So I bought new injectors and a new injector pump from typ4. Installed everything, new fuel filter and glow plugs. Got it running and the knock is still there. I advanced and retarded the timing a few degrees several times with no noticeable difference in the knock.

    I noticed when removing the old glow plug from the #7 cylinder it was kind of difficult to remove (like sliding in and out) and then putting the new one in it was tricky to slide in and get down to the threads. Could there be a bunch of carbon build up on the head messing with the glow plug and the spray pattern?

    For shits and giggles I checked my coolant reservoir today and I know it was perfectly clean when I purchased the truck and now there is black liquid in the bottom.... The blow by is still the same and the oil is still black and not milky (I also changed the oil when I got home no milkyness when it was drained) The only time I drove the truck was the test drive and the drive home.

    Here is a video of the knock and me cracking the injector line.



    Im ready to rebuild this motor if I have to but it needs to be done soon, i only have the remainder of this month and October while I work full time and to do the rebuild. I just need a reliable vehicle I have to tow a trailer loaded with 9000 lbs nearly 800 miles on November 1st when I move home from the military. Obviously since its an IDI I have to sleeve the cylinders and since its a turbo get the turbo piston rings. Rod, main and cam bearings and fel pro gaskets. What else am I in for?
     
    Last edited: Aug 11, 2018
  2. gandalf

    gandalf Senior Member

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    Good morning, Michael. I'll hit, very briefly, on each of the two problems.

    Oil in the coolant---I'd look carefully at the oil cooler, located near the oil filter. It might need rebuilding. That's one of the more common places for oil and water to mix.

    You did not actually time the engine when you changed out the IP? That is a "must do" unless you're very lucky. Simply placing the timing marks the same doesn't work. Each IP can be different. Those were originally put on at the factory as an approximation of where to start the timing process. If you got the new IP from @typ4 we can rest assured that the IP itself is good. However, you must time it.

    You might want to consider cleaning the injector bore on #7. When you removed to old injectors are you sure all copper washers came out with the old injectors? Two washers down the bore can mess things up. Clean it out with a brush from your 12ga shotgun. Make sure the ridge at the bottom is clean.

    That's as far as I can take you. I'm sure others will also offer suggestions.
     
  3. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    Gandalf, I was sure to remove all of the copper washers before installing each injector, the number 7 injector was especially dirty in the bore so I sprayed some compressed air down there. like i said i also noticed installing the #7 glow plug was a bit tricky and I had to persuade the tip with more force than just gravity into the hole before the threads would catch. I think maybe this is just bad luck and bad timing(not of the engine), maybe he hadnt changed the oil recent enough but it was at the full mark when the engine was warm and maybe I could have been more gentle on the truck on the highway? I am by no means a speed demon but I was going about 65 mph with ~5500 lbs behind me. Performance of the truck didnt change noticably between when i purchased it and when it started knocking but again it all happened my first (and last :frustrate) time driving it.

    I did not clean the injector bore though I suppose its worth a shot. Im only skeptical of the dirty bore being an issue because I can say for certain the engine was not knocking before I started my journey home. Should i put a camera into the #7 Cylinder through the glow plug to see if its a cracked piston?

    I have not actually timed the engine with the new pump, that is correct. However, I did make several adjustments(+- 16th of an inch) in both directions, in 1/32 increments from the mark where it was before I pulled it but the knock is extremely persistent. I figured I would jus tchange out the pump while I was doing the injectors but now it seems like ive spent an addtional $1000 that maybe I didnt need to. Once everything is running smooth at least I can rest easy for a while. I dont even have the injector pulse machine to do the timing I was planning on doing at a diesel performance place if the knock went away. Same cylinder same knock. The new injectors and pump didnt change anything and like you said we know that the injectors and IP are reliably good.

    Thank you for the oil cooler suggestion, I guess if I pull the engine it would be a good time to take care of the oil cooler.

    Luckily I have a 2006 VW Jetta TDI to tote me around everywhere. I only bought this truck to move home with and then use as a work truck when needed. These things arent cheap in NC either. A non running truck sells for 2500.
     
    Last edited: Aug 11, 2018
  4. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    You won't see into the cylinder itself through the glow plug or injector holes. You'll just be able to look into the precup in the head. Instead of pulling the engine, why don't you try cracking the injector lines one at a time to see if you can isolate which cylinder it's knocking on? You can pull the oil cooler with the engine still in the truck although it helps to remove the two nuts off of the bottom of the driver's side motor mount and raise that side of the engine to gain a little bit of clearance. This is messy, but it's still easier than pulling the engine to do it.
     
  5. Macrobb

    Macrobb Full Access Member

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    Removing the oil cooler is easy to do in the truck. Just remove the steering shaft(one bolt holding it to the steering box, one bolt on the top end holding it to the column). This gives you a nice work area to pull it up and out.
     
  6. saburai

    saburai Full Access Member

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    Hi Michael, thanks for your detailed and well written posts. I've got nothing to add. I'll let the IDI Wizards continue their diagnosis. I just wanted to make sure that everyone read the post where you posted the video and that they did indeed watch the video. Good luck!
     
  7. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    I have cracked all the injectors and it only stops with the #7 cracked. Same issue i was having before I replaced the injectors and injector pump..

    UPDATE: I just went out there to triple check all the injectors. It is in fact the #7 cylinder knocking. When I crack the injector the knock appears to go away but when I take the stethoscope to it I can still hear the knock internally and only in that cylinder. Every other cylinder has a beautiful repeating diesel glurg, except for poor #5 because its getting a little residual knock noise from #7. Im expecting there to be a little something wild with the precup when i pull the heads but we shall see.

    I am going to pull the engine and rebuild it. See if I can get a reliable machinist somewhere within 3 hours to sleeve the block using the nitrogen process. If not ill take it to a local guy ive used on other heads and have him magnaflux and check the crank and bores and probably clean up the valves, and i will take my lucky chances with a flex hone tool or have the machine shop do it. After reading about @hesutton overboring .020 on a 7.3 it makes me feel marginally better.

    Im going to get a cam from type4, put in the the comp 910 springs. switch to the electric lift pump and rebuild the oil cooler. Cross my fingers everything is still good its just a rod bearing that I caught early. Hopefully all before September 2nd haha!

    My truck did run out of fuel during diagnostics lol the past 2 days I had to start it up with a little gas pedal. Last time shut it off she wouldnt start and the front tank is on way low E. The indicator barely works anyhow. Guy before me says he never used the rear tank and he had the truck for about a year so I dont want to do any troubleshooting using that tank although it is tempting because i did put about 5 gallons in there on the way home and some diesel kleen fuel tank cleaner... Or I could fill up the front tank install the electric pump and see if for some reason that removes the knock. The truck never had issues revving or running or getting started so I dont think the fuel pump is an issue and my driveway is a steep uphill that its been sittting on (chalked) for weeks. I think its time to face the music.

    Thank you guys for all of the information and input. Glad to be a member here.

    EDIT: Northern Autoparts kits are acceptable from a few posts I have seen but can any of you more experienced guys confirm this?
     
    Last edited: Aug 12, 2018
  8. 79jasper

    79jasper Chickenhawk

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    You've obviously done your research, that's great.
    Typically it's not that common to see a cracked piston, but it does happen. The one I saw was missing the skirt.
    Could also be in the valvetrain. Maybe pull the valvecover.

    Sent from my SAMSUNG-SM-G920A using Tapatalk
     
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  9. Macrobb

    Macrobb Full Access Member

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    Btw, my one rebuilt motor (7.3)was overbored by .030". It snapped a rod a year later(all bearings were fine) but it never had any cylinder wall or coolant issues.
     
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  10. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    Thanks for sharing. Thats reshing to hear.
     
  11. typ4

    typ4 Supporting Member Supporting Member

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    You likely have a rod bearing bad or broken piston. Don't run it anymore
     
  12. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    I am going to pull the passenger valve cover and if everything looks normal shes coming out. Just got a 1 ton engine stand for $40. The stars are aligning.
     
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  13. Fred Hemer

    Fred Hemer Full Access Member

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    Did you pull the glow plug to see if there was a tip missing???!
     
  14. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    Yes. In my first post I mentioned installing new glow plugs, the old ones were motorcrafts and they all had strong full tips.:Thumbs Up
     
    Last edited: Aug 13, 2018
  15. MICHAEL MICHAUD

    MICHAEL MICHAUD Registered User

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    Update: The oil pan is hollow so there are no cylinder pieces down there. A better view of the valvetrain reveals no damage whatsoever.

    Pulling this engine was a pain in my ass and nearly ripped off the passenger side rear ground strap haha but she is out. I had to pull the clip and the core support because my truck has a 3 inch lift and is on a hill but i did not need to remove the hood. I left the transmission in. I should have disconnected the pressure plate and clutch and left it on the spline it would have made it very easy so ill probably install it that way.

    Note to future pullers: Lift up the engine till you see the mounts come up. Check the back of the engine where it meets the bell housing. If there is a gap the just gently but abruptly lift/ shake from the harmonic balancer and she will free herself easily from the trans. Also before the oil pan could lift up to clear the support I looked into the trans and a finger from the pressure plate was holding onto the spline. Put my jack handle in there to press the finger in so it would come off the spline and it was a breeze from there. I also had a jack under the trans to move it up or down as necessary as well as support the front of it.



    engine pull.png

    Now for disassembly of the engine. Hopefully it doesn't take so long I forget how to put the front end back together, or all of those engine connects....o_O
     
    Last edited: Aug 17, 2018 at 8:19 PM

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