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2011 Prius sounds horrible after cleaning EGR cooler

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by GeekPriest, Jun 30, 2021.

  1. GeekPriest

    GeekPriest Junior Member

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    I recently removed the EGR cooler assembly from my 2011 to clean it. (It was 100% clogged.) I've put everything back together (except for the cowl and wipers), connected the coolant hoses, EGR valve circuit connector, and MAF circuit connector, and refilled the coolant (expecting it to need further topping off as it sucks in the new coolant and bleeds out the air).

    Car starts, but sounds like total junk. Clattering and vibration everywhere. No misfire counts on the scanner, which was my first thought.

    So now I'm wondering whether something happened to the synergy drive (MG1/MG2). There's a coolant splash shield over it (it looks like), so I simply used a pan under the car to catch the coolant when I pulled the hoses off the EGR cooler. But now I'm wondering if something got into it.

    Any pointers on how to figure this out? The noise is awful enough that I don't want to run it very long at all.
     
  2. Peter123

    Peter123 Active Member

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    How much oil do you have in it? If you have a normal amount, does the noise go away after a minute of running the engine at idle?
     
  3. tankyuong

    tankyuong Senior Member

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    Normal yo run rough after cleaning
     
  4. PriusCamper

    PriusCamper Senior Member

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    Try disconnecting the 12v battery so all the engine settings are reset. I think your current engine settings are left over from before you did all the work.
     
  5. GeekPriest

    GeekPriest Junior Member

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    I have disconnected the 12V battery overnight. Will see if starting with un-adapted engine parameters helps. If not, I'll pursue checking the EGR valve's function. I noticed the motor end of the valve was rather warm after running the engine for just 30s. Here's hoping I can work a wrench in there to get the valve off without removing the entire cooler again.

    Will report back.
     
  6. GeekPriest

    GeekPriest Junior Member

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    Reconnected 12V power. When the ICE started, it sounded normal for about 2-3 seconds then started the terrible noise again.
     
  7. GeekPriest

    GeekPriest Junior Member

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    I'll try pulling the EGR valve later to see if it responds.
     
  8. gromittoo

    gromittoo Active Member

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    Were you able to get the EGR extracted without the cooler? Just curious, cause I had a reason to remove only the EGR.
     
  9. Otium

    Otium New Member

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    Delete. Posted in wrong thread erroneously.
     
  10. GeekPriest

    GeekPriest Junior Member

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    Yes, although it's still a bit involved. I removed the air box and front EGR tube (between the valve and intake manifold along with the wiring harness bracket attached to the EGR valve. I then removed the nuts, studs, and gasket connecting the EGR cooler to the exhaust manifold tube. I loosened the bottom nut (behind the lower coolant hose going to the EGR cooler) and then rotated the EGR assembly forward enough to get a socket on the upper rear-facing nut.

    If there's a time savings, it's in not having to disconnect coolant lines (with a possible refill) and not having to replace that difficult lower nut by the coolant hose.

    Conceivably, a really thin 12mm offset wrench might be able to deal with the upper EGR valve bolt without this effort, but nothing I had worked.
     
  11. gromittoo

    gromittoo Active Member

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    OK it is about a difficult as I thought it might be.

    To save the hassle of pinching the cooling hoses, I just drain enough coolant into a clean pan, with the intent of pouring it back in.

    Yes that bottom nut is a b%^&ch. The tool gods demanded a sacrifice, and I lost a 12mm socket and my last 3 inch extension to that nut.

    I was tempted to spot weld a deep 12mm socket to the nut. That way I could thread the nut on by hand , and finish it with a more accessible ratchet. The socket would remain in the engine for the next time it has to come off. I don't have a spot welder, however.

    I then had the thought that the nut should have been made from a piece of 12mm hex stock about 3.5 inches long. There would be an internal thread to match the original nut. Again, that way, you could start the nut by hand, and finish it with a more accessible ratchet. Such a fastener would be easy to fabricate in bulk. I have 2 Prius V's, so it might be worth the trouble. to make a bunch of these, and sell them in the Prius Shop.
     
  12. privilege

    privilege Active Member

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    upload a video ?
     
  13. ASRDogman

    ASRDogman Senior Member

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    Just leave that nut off. I personally had not problem removing it or installing it.
    But decided to leave it off the 2nd time. Because I dropped one of the nuts for the cooler
    where it attaches to the exhaust at the bottom, so I used that nut instead because it had fallen
    into the frame somewhere and I couldn't find it. :whistle:
    But after that, I hear a rattle from time to time in the engine. Something I've lived with.

     
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  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Yes just leave the coolers bottom nut off. For extra marks back out it’s stud as well. And pinching hoses is a fool’s mission: drain 2 qts before disconnecting any coolant hoses, into a clean container; add it to the reservoir when done, with the vent screw (2010/2011 model year) open while filling, till coolant flows out, then close. Later model years are missing the vent screw, but you can just pull off the coolant hose right there, achieve the same venting function.

    more info:

    Bad Flywheel | PriusChat
     
  15. gromittoo

    gromittoo Active Member

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    My thinking is this: If you want to put a nut on that stud, it would be nice to use a nut that you can grab with your fingers in that tight space.

    There is a part called a Hex Nut Coupler. Another name would be a Hex Threaded Standoff. I am not sure what the thread size is on the bottom bolt, but it is either M8 x 1.25 or the M6 x 1.0. The part would need to be Stainless.

    What I found on Amazon is a Stainless Hex Nut Coupler in M8 x1.25 but was was only 40mm long (or about 1.5 inches). To truly be useful, the coupler needs to be a bit longer like 80mm. The one I found on Amazon was 13mm hex stock, but to make this really difficult nut more manageable, I can tolerate using an odd size socket.
    Coupler.JPG


    The $10 price is for 2 pieces. The same seller has a listing for M6 x 1.0 x 30mm long.
     
  16. ASRDogman

    ASRDogman Senior Member

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    ORRRR,,,,,, you could leave it off.
    You still have to remove the stud.
    SOOOO,,,,,, you could use a bolt.
    ORRRR,,,,,, you could leave it off.
     
  17. Raytheeagle

    Raytheeagle Senior Member

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    Start a collection(y).:

    1A3F4E71-5D66-4AEF-91A9-38098A864D4D.jpeg
     
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  18. Mendel Leisk

    Mendel Leisk Senior Member

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    Remove the stud too. Life goes on. (y)
     
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  19. GeekPriest

    GeekPriest Junior Member

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    A quick summary of where I am: EGR is working much better, but there's a persistent misfire on cylinder 4 on deceleration after being at speed AND with EGR connected (plugged in).

    What has been done:
    1. EGR cooler cleaned and reinstalled. (It's clear end to end.)
    2. EGR valve replaced. The old one (probably factory) was sticking. I considered cleaning it, but decided to replace it just to get on with it.
    3. New coolant in the engine. (Why not?)

    What I observe:
    1. The original problem before the EGR service was that the engine would vibrate and stutter on deceleration with EGR connected. I disconnected the EGR wiring harness to get around the problem until I could clean the EGR as above.

    2. NOW, after a bit of driving at speed, varying it up and down to mix acceleration and deceleration, the engine is not stuttering nearly as badly as it was. I credit this to better EGR flow and the re-learning of EGR valve positions after the variable driving test.

    3. NOW, however, cylinder 4 also has a consistent, heavy misfire on deceleration, which causes the stuttering effect I observed before. It's not as bad as before the EGR service, but it's still noticeable and concerning.
    • It HAPPENS when decelerating (but not coasting), with the EGR counts dropping from a high of 75 or so down to something like 25. Thus, exhaust gases are still being introduced into the intake.
    • It DOES NOT HAPPEN under hard acceleration (or any acceleration, for that matter).
    • It DOES NOT HAPPEN when coasting, with the engine spinning 1000-1100 rpm.
    • It DOES NOT HAPPEN when I disconnect the EGR valve again. The misfire counts stay at 0 across the board in this case.
    It is this last point that I think holds a clue. I'm trying to figure out what would be different in cylinder 4 (which I assume is closest to the EGR pipe going into the intake) with versus without EGR to cause a misfire. I can check ignition coils, but I'd expect an ignition coil misfire to occur regardless of EGR. The plugs are all fairly new NGKs installed about six months ago. This leads me to think it's a misfire dependent on air or fuel.

    I did not clean the intake during all of this, so that's a possibility, but I'm really at a loss to explain how the intake would affect things UNLESS it's simply because cylinder 4's intake passage, being closer to the EGR pipe, has carbon buildup sufficient to mess with the air/fuel induction.

    Any thoughts here?
     
  20. Grit

    Grit Senior Member

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    o_O
     
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