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2010 Prius EGR Cooler Leak

Discussion in 'Gen 3 Prius Technical Discussion' started by Eugene Kurtz, Dec 24, 2022.

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  1. Eugene Kurtz

    Eugene Kurtz New Member

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    After replacing the head gasket in my 2010 Prius, I have a coolant leak where the EGR cooler bolts up to the exhaust. There is a fast drip of coolant at the flange at the back of the cooler. I assume there shouldn’t be any coolant here so the EGR cooler must have an internal leak? Anyone else run into this issue?

    upload_2022-12-24_16-29-56.png
     
    #1 Eugene Kurtz, Dec 24, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    Sounds like an internal leak all right.

    Was the cooler ever subjected to an especially violent cleaning?
     
    #2 ChapmanF, Dec 24, 2022
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  3. Eugene Kurtz

    Eugene Kurtz New Member

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    No cleaning, just unbolted and reinstalled as part of the head gasket replacement. The car has ~250k miles and the EGR valve was replaced at 150k. As far as I know the cooler is original but not sure if it was cleaned when the valve was replaced.
    I didn’t notice any external leaks before doing the head gasket and was surprised to see coolant leaking from the flange. Thought I missed a hose clamp.
     
    #3 Eugene Kurtz, Dec 24, 2022
    Last edited: Dec 24, 2022
  4. xliderider

    xliderider Senior Member

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    I'd suspect that one of the hoses has a bad/loose connection before looking for an internal leak in the EGR cooler coolant system.

    Perhaps one of the hose connections is leaking, and it just looks like it's coming from that back area of the cooler?

    Posted via the PriusChat mobile app.
     
    #4 xliderider, Dec 24, 2022
  5. Eugene Kurtz

    Eugene Kurtz New Member

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    I was pretty sure it was from the flange but that’s definitely worth double checking. Thanks for the input.
     
    #5 Eugene Kurtz, Dec 24, 2022
  6. CR94

    CR94 Senior Member

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    Check to be sure coolant isn't leaking from the top hose connection and running down the back side.

    A true internal leak of coolant into the EGR stream could be disastrous.
     
    #6 CR94, Dec 24, 2022
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  7. Eugene Kurtz

    Eugene Kurtz New Member

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    You guys were right, it was the hose connection! Thank you!!!

    upload_2022-12-25_9-42-34.png
     
    #7 Eugene Kurtz, Dec 25, 2022
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  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    How recently was the head gasket replaced?

    If the EGR components (including intake manifold) are still uncleaned you definitely want to do that, ASAP.

    In the course of cleaning you’ll be able to pressure test the cooler’s coolant passages easy enough. if it doesn’t hold pressure you’ll need to replace.
     
    #8 Mendel Leisk, Dec 25, 2022
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Good to know. (y) Now clean them EGR components, don't slack off.
     
    #9 Mendel Leisk, Dec 25, 2022
    Last edited: Dec 25, 2022
  10. Eugene Kurtz

    Eugene Kurtz New Member

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    I just replaced the head gasket this week. The intake EGR ports looked reasonably clean so I just blew out the ports to make sure they weren’t clogged before reinstalling. The pipe from the EGR valve also looked good so I decided to leave that alone for now. Aside from the coolant leak (now fixed by adjusting the hose clamp) things went back together well and the engine is running smooth (no more shakes and rattles on start up). I’m thinking to drive it for a while then maybe consider in the future.

    Is there any downside to waiting for symptoms before cleaning?

    Thanks for all the links, a lot of great info here!
     
    #10 Eugene Kurtz, Dec 25, 2022
  11. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Yes.
     
    #11 Mendel Leisk, Dec 26, 2022
  12. ColoPriusV

    ColoPriusV Member

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    Surprised no one has advised installing an oil catch can yet. OP lives in PA and the amount of oil/water/gas vapor an OCC eliminates from the intake during winter months is astonishing, and especially on an engine with 250K miles, a prior blown head gasket - and quite possibly worn piston rings.
     
    #12 ColoPriusV, Jan 8, 2023
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