EGR Valve sticking

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Willy Toast, Mar 4, 2021.

  1. Willy Toast

    Willy Toast Junior Member

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    I am curious why no one seems to look at the EGR valve stem? My 2012 Prius v had only 59,000 miles on it and most of the EGR system was pretty good. However when I took off the EGR valve cover and unscrewed the rotor I found the valve stem was sticking pretty badly even though there was only a thin film -- can't get thick if valve still moves at all -- on the valve stem. I scraped the stem off with a small tool through the inlet (exhaust side) port and added lithium grease while manually moving the valve stem about a 100 times. It made a real difference in how my Prius ran.
    It got rid of the nasty idle damper knock though there is still a strange rumble on light acceleration.

    Also the Canadian Toyota warranty extension W11 specifically refers to this issue.

    Question: Why is this not one of the first points of focus when looking at the EGR system faults; Especially at lower mileage? (Attn ChapmanF, Mendel Leisk, Ragingfit)
     
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  2. rjparker

    rjparker Senior Member

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    Dealers will replace the egr valve and cooler rather than cleaning them; the diy crowd just cleans them like you did. The cooler is difficult to remove, often overlooked and clogs sooner so its the star of the show.
     
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  3. Raytheeagle

    Raytheeagle Senior Member

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    No one is a big category;).

    The dozen or so egr's I've cleaned guess what I've done:whistle:.

    The screws require an impact screwdriver to remove due to the dissimilar materials of construction, but the impact screwdriver is the right tool for the job:).

    I don't know if another way to clean the seating area for the plunger, so I take the screws off and give it a thorough cleanse(y).
     
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  4. Willy Toast

    Willy Toast Junior Member

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    In my case at first I was thinking the intake manifold ports and the EGR cooler were too clean to be a problem. But then I found that the valve stem was sticking anyway. The valve is an unusual design where in the open position the part of the stem that goes into the packing is exposed to the flow.
     
  5. Willy Toast

    Willy Toast Junior Member

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    I am a bit of a valve guy. This is an odd design where in the open position the stem is fully out in the moving flow. When it shuts it pulls into the packing area bringing whatever along with it. It does not take much to stick.
     
  6. Willy Toast

    Willy Toast Junior Member

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    I wonder if the valve stem surface is as important as the plunger seat area? The plunger seat applies only when fully shut. The stem might prevent it from getting fully shut. Don't really know what that meant in terms of engine behavior and damper rattle.

    To clean the stem one must also take the valve off the EGR cooler as with your full cleaning. Then you can see all the stem that sits in the flow when it is open.
    If you remove the cap and spin off the rotor you can push most of the stem out for scaping. Mine had a coating of carbon on all the stem that you could expose buy manually opening the valve. I did not attempt to take the stem out of the valve just scraped what i could -- I used a hook for the back side -- and added grease then pressed the stem about ten times wiped off the now dirty grease and repeated adding a little fresh grease again. I did this a few times to reduce the ratio of carbon to grease in the stem packing guide area. I was careful to remove excess grease with a rag before spinning the rotor back on and reassembling.
     
  7. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Maybe recheck it before too long; see how that grease is working. They come from the factory without grease; you’re making a change. Might be for the better, but who knows.
     
  8. ASRDogman

    ASRDogman Senior Member

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    The grease will probably harden up from the heat and exhaust gas. Which will probably cause
    it to want to stick.
    I think(not sure) that the guide is like for the head, bronse. They do not need lubrication.

     
  9. Willy Toast

    Willy Toast Junior Member

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    The stem is a yellow metal, brass alloy. The grease I picked is similar in appearance to the rotor thread grease used by Toyota on the stem top. The stem bearing design does not seem suitable for carbon deposits. In 2013 they may have corrected this design.
    None the less it moved better with the grease added than with the carbon deposit alone. I no longer have the heavy start shake only a weakness rumble upon light acceleration. Otherwise very nice at highway speed.
    I did not want to try getting the stem out of the valve.
    Correction/Clarification: Access to the stem for scraping is through the port where the angle piece is; not from cooler port.
     
  10. Willy Toast

    Willy Toast Junior Member

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    I agree. I only did this as a temporary fix. I may buy a new valve as a spare about $250.00. Dealer indicated I may have a chance at warranty but I want to figure out the other problem the rumble on light acceleration before I make a dealer appointment. Does a scanner help with this?
     
  11. wheezyglider

    wheezyglider Active Member

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    In my fuzzy memory is a notion that if the valve is replaced with a newer revision then one is meant to update the ECU. (Based IIRC on the EGR Valve-related TSB, apologies for not digging up a firm reference.) I wonder if anyone has DIY'ed that using Techstream. I wouldn't worry about it until just before (or more probably just after) clicking the "buy it now" button on a new EGR valve...
     
  12. Willy Toast

    Willy Toast Junior Member

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    That right there is an update to the ECU involved. If I install the new EGR valve with the new part number I will certainly have the dealer do that work.
    I have a few other jobs to complete first. The PCV valve, check the damper area and change the transmission fluid first. Plus some general engine rumble possible causes in video research before I am ready to approach the dealer.
     
  13. wheezyglider

    wheezyglider Active Member

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    That TSB regarding the sticking EGR valve was hard enough to find that I'm putting its info here:
    T-SB-0027-16 MIL "ON" DTC P0401 and/or Rattle After Cold Soak

    [The copy I found on PC didn't have all the pages. But the one on tsbsearch.com did, including the ECU update instructions.]

    I had actually forgotten that Toyota officially linked the cold start rattle to the sticking EGR valve. (And my 2010 still rattles occasionally on start up, without coolant loss. When I cleaned the EGR circuit I wasn't able to get the valve open.)
     

    Attached Files:

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  14. ASRDogman

    ASRDogman Senior Member

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    What do they mean by cold "soak"?
    The extra fuel for a cold start???

     
  15. ChapmanF

    ChapmanF Senior Member

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    They mean sitting powered off for long enough that everything has come down to surrounding cold temperatures.

    Sort of like the more commonly-heard "heat soak", just in the other direction.
     
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  16. Willy Toast

    Willy Toast Junior Member

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    I guess I was lucky the two screws came of easily and I was able to confirm that the stem was sticking in place. Did not take much to get it moving more freely. I believe my vehicle has a worn damper plate. I have identical conditions to another posting where the damper was swapped out for a new one. The sticking EGR probably just made the worn damper condition really noisy and rattling.
     
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