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EGR clogging - is it possible to avoid it?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by mtl, May 29, 2022.

  1. mtl

    mtl Junior Member

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    First, a quick background. This is my first Toyota hybrid (Auris 2011 (E150) with Prius 3rd generation drivetrain).
    I have owned multiple petrol and diesel cars. Last five cars were VW diesels that also can have EGR clogging problems. But even though I drive spiritually on backroads I have majority (90%) of the drives on highways where I usually keep the rpms between 1.600 and 1.800, which according to the theory is ideal for clogging the EGR and other parts. But I have never had a problem with them and I had two cars with 170.000 miles on them. Current diesel car has 150.000 and until now also no signs of any problems with EGR. Everybody (including mechanics) were telling me that I will have fully clogged EGR soon for all my diesel cars.
    Well, why I did not have any problems with EGR? I think that this is because every drive that I take, when the engine oil is at operating temperature, I just floor it (full kick down) once for cca. 20-30 seconds. Now diesel cars have DPF filters, but before them I could just see a small black cloud of smoke that went out of the tailpipe. So most of the gunk was pushed through the engine and thus did not clog the EGR and all other parts. Well, at least this is my theory.

    So, now I am asking myself if this would work also on Prius 3 hybrid system. Because according to the experience of owners EGR system on this engine is even more prone to clogging. And I would think that this is because the system always tries to keep the engine in lower rpms (better fuel economy) and also majority of the Toyota hybrid drivers drive with low consumption on their mind. So, the gunk just cannot be pushed through the system and thus it slowly clogs it. What do you think of my theory?
    Anyway, I will be using my tactics also on this hybrid car and I hope it will help a little. I can easily trade in a small decreas in fuel economy for a longterm lower costs of servicing.

    PS: My just bought used Auris hybrid has 85.000 miles and I am planning to do a preventive EGR cleaning, so I can see how clogged the EGR system is.
     
    #1 mtl, May 29, 2022
    Last edited: May 29, 2022
    mjoo and bisco like this.
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    I think it's the EGR design in third gen (model year 2010~2015 in North America), which is responsible for the carbon clogging. I don't think spirited driving will prevent the clogging. Periodic cleaning, or replacement of components, is the only solution. The latter is all dealerships will offer, at absurd prices.

    When toyota introduced fourth gen (model year 2016 and onward in North America), they actually mention new design of EGR. And so far there have been no clogging reports for 4th gen.

    I also can't recall any fourth gen blown head gasket report here. There is a thread here on that subject, and I think none have been reported to date.
     
  3. CR94

    CR94 Senior Member

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    As for the thread title question, I doubt there's a legal, practical way to completely avoid soot accumulation in the EGR cooler. Clearly some examples are worse than others, and I'd bet that has a lot to do with operating conditions, the owner's habits, etc. Any circumstance that leads to burning rich fuel mixture or increases oil consumption won't help matters.

    "Flooring it" isn't going to blow soot from the cooler out the tailpipe.
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    There’s a steady feed of oil vapour from the low-on-the-block PCV circuit. So oil catch can may help. That and periodic cleaning of the EGR circuit, say every 50k. Italian tune up does squat.
     
  5. ReadyToRoll

    ReadyToRoll Junior Member

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    Related to or perhaps the same issue, how much blow by should be noticed when removing the oil filler cap while the engine is running? My Gen 3 has a great amount of air flowing there, I do not see how the PCV system could handle it if that is the same system air.
     
  6. CR94

    CR94 Senior Member

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    A "great amount of air" and other gases can flow in and out there. even if the engine is in perfect shape. The PCV valve only has to handle the net outflow (from blowby). The inside of my PCV fresh-air inlet hose (the hose connecting the air inlet duct to top of the valve cover) stays dry, so there must not be more blowby than the PCV valve can handle.