EGR cooler residue

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by xliderider, Sep 2, 2021.

  1. xliderider

    xliderider Senior Member

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    Anyone else have a white buildup inside the coolant passages of their EGR cooler?

    I suspect it's dried up coolant from when it was removed from a high mileage car that wasn't flushed out with water. It comes out as a white, flaky, papery, film that will crumble to white powder. But it is adhered to the inlet/outlet inner walls pretty good.

    In the picture showing the deeper view into the cooler, the residue is the darker gray color against the shiny silver surface of the stainless steel.

    I tried rinsing/soaking it with hot, almost boiling water, after plugging the inlets/outlets. That rinsed out some, then I poured some white vinegar (mild acid) in and let it sit for a bit, then followed up with hot water flushes. I still see it coating the deeper surfaces.

    Followed up the rinses with a heat gun on low setting to try and dry it out. The hot air current is blowing out bits of this stuff out, I guess as the water dries out and releases the stuff that's been loosened.

    Should I be concerned about this, or will the little bit of this residue not be a problem when I put in new coolant after the EGR cooler swap? 20210902_103305.jpeg 20210902_104642.jpeg

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  2. jzchen

    jzchen Senior Member

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    Phosphate from coolant maybe?
     
  3. xliderider

    xliderider Senior Member

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    That would be my guess as well, or whatever remains after SLLC coolant dries.

    I'm probably over thinking this. The inner surfaces of the entire cooling system in my car is probably coated in some kind of slimy coolant residue by now anyway.

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  4. jzchen

    jzchen Senior Member

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    General Chemistry was not really my forte... Trying to dig up a good solvent for phosphate/antifreeze.
     
  5. xliderider

    xliderider Senior Member

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    I'm sure I could just get a big disposable aluminum baking or roasting pan and boil the entire EGR cooler in a water bath on my propane turkey fryer.

    Whatever the residue is, it should get softened and dissolve in water, the universal solvent.

    It's a good thing that the EGR cooler is made out of pretty robust stuff, namely stainless steel.

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  6. Raytheeagle

    Raytheeagle Senior Member

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    I've seen that on every cooler I've cleaned (which is around a dozen);).

    So not uncommon :).

    Definitely as temperatures in the system rise, one of the components is salting out:cool:.

    If you wanted to get data, do a pre sample then after x thousands of miles, do a metals analysis and see what is lower:whistle:.

    Or just swap out the coolant and save your pennies for something else(y).
     
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  7. xliderider

    xliderider Senior Member

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    OK, good to know it's common, and probably nothing to be concerned about.

    I'll just leave it.

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  8. jzchen

    jzchen Senior Member

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    #8 jzchen, Sep 3, 2021
    Last edited: Sep 3, 2021
  9. StarCaller

    StarCaller Senior Member

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    not much of an inside difference to the original toyota egr-cooler (not even really cheaper) /

    [​IMG]
     
    #9 StarCaller, Sep 3, 2021
    Last edited: Sep 3, 2021
  10. ChapmanF

    ChapmanF Senior Member

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    Wasn't the whole thrust of that sell sheet that the original is a fin-and-tube design (as seen in the photo above) and the Dorman uses larger spiral tubes less prone to clogging?

    Or is that a photo of what Dorman sells for Gen 3?

    Edit: yeah, it looks like for some makes and models, the cooler they sell is in their "OE FIX" line, and uses the spiral tubes for reduced clogging.

    But not the one they sell for Gen 3 Prius.
     
    #10 ChapmanF, Sep 3, 2021
    Last edited: Sep 3, 2021
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  11. jzchen

    jzchen Senior Member

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    That's borderline false advertising it is the sell sheet on the same page as the one they list for 2012 hatchback and v. How did you figure it is not the design of the listed part?
     
  12. ChapmanF

    ChapmanF Senior Member

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    Recognized that the photo posted by StarCaller in #9 is the photo from Dorman's page for that part, and on that page, it is not described as "OE FIX".

    Compared to, for example, this EGR cooler for a Ford, where you do see their "OE FIX" logo.

    [​IMG]
     
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  13. xliderider

    xliderider Senior Member

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    Both coolant and exhaust flow through the EGR cooler, in separate circuits.

    Similar to an air to liquid intercooler on turbocharged vehicles.

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  14. xliderider

    xliderider Senior Member

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    The EGR cooler is stainless steel, I'm sure of it, because I've put in HD degeaser, drain cleaner, Oxy-Clean, and near boiling water. Sometimes plugged on one end and soaked for days with straight drain cleaner.

    Through it all, no rust or damage, except for the nuts welded on the very end of the cooler, which have a light coating of rust now.

    However, while I was using my handy, indispensable magnetic pick-up tool to keep nuts and gaskets from falling down while trying to reach around hoses to grab them, I noticed that the EGR cooler body is strongly attracted to the magnet.

    I always thought that stainless steel was non-ferrous and didn't attract magnets. It must have iron in it but get its stainless quality from other high level metals like nickel and chromium.

    Found this information on the web:

    Magnetic Properties of 304 & 316 Stainless Steel



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  15. Paul E. Highway

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  16. StarCaller

    StarCaller Senior Member

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    hmm, to me it looks like it has the same square cooling canals like the original from Toyota /
    (cropped image is the dorman cooler)

    [​IMG]
     
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  17. xliderider

    xliderider Senior Member

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    I wonder if a wire could be pushed through a spiralized cooler though, that is the most effective way I've found to loosen crud built up in the cooler.
     
    #17 xliderider, Sep 7, 2021
    Last edited: Sep 7, 2021
  18. jzchen

    jzchen Senior Member

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    Have you tried rinsing with a non-phosphate containing coolant/antifreeze?
     
  19. xliderider

    xliderider Senior Member

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    I'm not worried about the coolant side of the EGR cooler anymore, since its been stated that it is common and nothing to worry about.

    I'm referring to the inside, exhaust exposed cooling fins and tubes. I would think that a straight through design like the OEM one is easier to clean than a "spiralized design".

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  20. jzchen

    jzchen Senior Member

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    I'm lost. Are we trying to clean the coolant side or exhaust gas side right now?

    EDIT-. Long day, reread your post I get what you're saying now. I think the temperature profile graph on the OE Fix means since it's more consistent through operating temperature range, less drop out as deposit formation...
     
    #20 jzchen, Sep 8, 2021
    Last edited: Sep 8, 2021
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