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Still P0401 after cleaning egr !! should we drive it?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ozmatt, Mar 27, 2021.

  1. ozmatt

    ozmatt Active Member

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    Hey Mendel, it's a little cheaper on eBay mate, I have messaged a couple eBay members that are selling good used valves really cheap to ask if they will send to AU but no reply yet lol! Theres a ton of good used valves getting about on there just not in Australia, surely I can source one somewhere, maybe someone will chime in over the easter period if I'm really lucky

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  2. Rocky Mountain Priusman

    Rocky Mountain Priusman Active Member

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    Any theories on why your plastic mechanical stop got so chewed up?
     
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  3. ozmatt

    ozmatt Active Member

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    My thoughts are the plastic thread in rotor gets flogged, so the rotor starts to run unevenly until it's so bad the dimple can glide over top of the plastic stop

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  4. ChapmanF

    ChapmanF Senior Member

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    I don't know, I might be cautiously optimistic. In your picture of the stem threads, I'm not sure I see the floggage you're referring to. I'm also pretty sure the plastic rotor is softer than the stem threads. [edit: sorry, I misread, I see you were talking about the rotor threads getting flogged.]

    My threads look kind of like this:

    nibd.jpg nibl.jpg

    They remind me a bit of the 'Acme'-style threads often used on actuator kinds of things (which this is).

    The uneven distribution of grease can maybe make them look uneven at a casual glance.

    I notice the stop nib there is no mere dimple. It is wide and stout, and has a definite genuine flat face to contact the ski jump. (It's genuinely not a dimple: there's no corresponding 'innie' on the underside of that disc.)

    The rotor has all kinds of slop as you are threading it onto the stem. It can swing side to side by a lot, and it has play up and down on the threads of about .029" (.74 mm).

    endp.jpg

    But that's kind of a "who cares?" I think. When it's all assembled, there is a snug bearing at either end, so that rotor isn't going anywhere sideways. The stouter of the two springs is there to hold the rotor always at the upper limit of its bearing end play. The smaller spring wants to make sure the valve stem itself is always at the upper limit of its play in the rotor threads. I could see an exception to that if the stem has gone sticky and the valve is trying to close; the rotor might then have to pull on it some. That could mean the nib comes .74 mm closer to missing the ski jump. (I just tried that with this one, though, and it still felt like a positive stop.)

    Does your nib look wide and flat like this one?

    I think a built-back-up ski jump might last a good long time. As you're threading the rotor by hand onto the stem, it should stop with a nice positive tok when it touches. If it feels a little scrape-y before the tok, it's built up a little too high. A person might deliberately build it up to the point of scrape-iness and then sand it down just a touch.

    And yes, when you let go of the rotor, the stout spring will send it a revolution or two back up. I've mentioned before that's kind of a nice thing, as in means once you have the stator all buttoned back on, you can look at the valve face and see the pintle is a few mm open. It should be an easy push back in with a thumb, and you feel and hear the rotor spinning inside as you do, which kind of confirms you haven't got anything cockeyed or jammed.

    You could compare your rotor up-and-down play on the threads to the .74 mm I got, maybe see how flogged those threads really are. (This is a used valve, I don't know the mileage, so I don't know what the play in a new one would be.)

    Looked at very closely, there is a slightly raised bump developing at the end of my ski jump. Kind of the opposite of being dug out, but possibly the very start of the process that does it.

    I'm sure once it starts to get dug out, it just goes and goes from there.
     
    #64 ChapmanF, Apr 1, 2021
    Last edited: Apr 1, 2021
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  5. ozmatt

    ozmatt Active Member

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    Thanks very much ChapmanF, this is extremely informative information for myself and priceless for the people that come after me chasing this very same problem on their prius, corolla or lexus ct200h which could possibly suffer from the same fate if lucky enough to get the mileage up!, my car has approx 450,000k km but it had a replacement engine around 80k km/ 3 years ago (@370k) I can not confirm if the replacement engine came with a cooler and valve assembly or the egr parts have been transferred over from the original engine! I'm leaning towards the later as I know most wreckers here in AU do not send out engines with any bolt ons whatsoever, so there is a very good chance this is the original valve from my car.


    When I took everything off to clean it, it wasn't very plugged, I would guess the cooler, egr valve and pipe got cleaned when the engine was installed 3 years ago

    Trying to think how could I measure my rotors endplay, all I have is a set of digital calipers which doesn't really work, but I will say from eye it would be very similar, a tad less or around about 1mm ..

    Here is a picture of my dimple, or whatever it's called.. btw no I don't normally get around posting pics of my dimple on the interwebs :)




    IMG_20210402_101255_533.jpeg IMG_20210402_101212_832.jpeg

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  6. ChapmanF

    ChapmanF Senior Member

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    I guess another possible cause I could imagine for a dug-out ski jump could be an overzealous valve reassembler....

    I think it could work ... just use the depth-gauge end, twice.

    Or are you saying the set of digital calipers actually doesn't work?
     
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Dial indicator with magnetic base are around $50 USD, at least in North America. Pays for itself every time you check brake rotors against spec.
     
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  8. ozmatt

    ozmatt Active Member

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    i was quite gentle with it, only screwed it down until i noticed slight resistance to suggest it was at its lowest point, definitely did not push the point or wrench it down, i have to think because my system was never plugged to begin with, this was actually the reason for my P0401 all along, i did not take my egr system apart to clean it for no reason, i got P0401 but when i took everything apart to clean was surprised to see it not that dirty

    they work, just not really the best tool for the job but i will try when i get near the car later tonight or tomorrow


    Mendel here in AU we use calipers for measuring brake rotors, i actually figured that would be world standard?

    Trying to get a few pictures of the inner thread in this rotor, it looks cone shaped to me and kind of flat threaded /flogged at the top, struggle to get a decent photo with this $100 phone (yeah im cheap) and im no photographer, that's for sure lol
     
    #68 ozmatt, Apr 1, 2021
    Last edited: Apr 1, 2021
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  9. ozmatt

    ozmatt Active Member

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    Also noticed there is probably nearly 1mm freeplay where the top bearing seats on rotor, could pack a shim under it to force rotor down near 1mm
    IMG_20210402_113356_182.jpeg IMG_20210402_113231_982.jpeg IMG_20210402_113229_168.jpeg IMG_20210402_113409_692.jpeg

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  10. ChapmanF

    ChapmanF Senior Member

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    Are you the person you think might have worked on it three years ago?

    That's what the stout spring's there for.
     
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  11. ozmatt

    ozmatt Active Member

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    no mate lol, i only purchased the car 11 months ago, i had the opportunity to buy it about 2 years ago from the original fleet owner but i didn't buy it at that stage, then the exact same car was for sale again last year with a bad hybrid battery for half the price it was the year earlier so i snapped it up straight away
     
  12. ChapmanF

    ChapmanF Senior Member

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    So if you think there's a possibility the previous owner had the EGR apart at some point, and you don't know how lovingly gentle they were ...
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    You took excellent pics, well focused and exposed. (y)
     
  14. ozmatt

    ozmatt Active Member

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    well, maybe.. this is all speculation but i doubt they would have taken the valve apart, more likely they would clean the cooler quickly and throw it back on new engine.. not really sure though.

    BTW honestly If i thought i had made a mistake or wrenched it down too hard, i would admit .. im not at all precious like that, im not a mechanic just familiar with basic jobs and tools and do my best where i can

    The service manager that i know from the original fleet and quite often speak with services so many cars and changes so many engines its impossible for him to remember the exact details of the job,hes always under the pump! told me it had an engine swap at 370k and they rarely get any accessories with engines,..

    when i first took it apart and seen the cooler gasket misfit at the exhaust manifold that to me verified either the engine had been out or the cooler had been cleaned, or both..

    did you happen to notice the pictures i most recently posted of the thread in rotor, tried to focus on the top portion of thread but its just near impossible
     
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  15. ozmatt

    ozmatt Active Member

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    Why thanks Mendel, i am only using a cheap Umidigi A7 phone lol, it cost like $106 does the job think its like a 16mp camera, 4gb ram /64 storage / android 10 . i do not buy expensive phones as A: im cheap - B: quite often drop it
     
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  16. ChapmanF

    ChapmanF Senior Member

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    I'm not convinced the threads really extend that far. It may look like they aren't well defined there because they aren't.
     
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  17. ozmatt

    ozmatt Active Member

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    Correct ChapmanF. just cleaned inside the rotor threads with some alcohol and what originally looked like flat or flogged thread was only grease, that top portion of the rotor is actually supposed to be flat, there is only three maybe four winds of thread in there total and they visually seem okay so i just don't know what to think

    also the groove in plastic stop on rotor does not match with the width of the metal stop on the valve, the grove in plastic stop is only maybe half as wide as the metal stop! if the metal stop caused this grove which i can only presume it did, it must have been contacting on one edge of the metal stop and not the full surface, if you get my lingo
     
  18. ChapmanF

    ChapmanF Senior Member

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    The nib looks kind of tapered. I'd rather it were not.
     
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  19. ozmatt

    ozmatt Active Member

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    when you say nib are you referring to the plastic stop piece inside rotor, sorry i don't even know what to call these nibs and knobs lol
     
  20. ozmatt

    ozmatt Active Member

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    Slightly better shot inside of rotor, after cleaning..

    Strange it's only got that little scrape through the centre of plastic nib when the two contact points are very similar sizes to each other

    IMG_20210402_143409_462.jpeg

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