Head Gasket Replacement - cylinder head is out - how to find a good machine shop?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Tyr, Dec 12, 2024.

  1. Tyr

    Tyr New Member

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    As both necessary and preventive, I am currently replacing the head gasket, the water pump, ignition coils, spark plugs, gaskets, etc. on my daughter's 2010 prius while she is away at school.

    The car has been sitting for 6 months before I was able to attempt this (12v is on a maintainer). I have removed everything and now I am asking for some guidance and advice.

    The only unexpected concern I see is the bottom of the cylinder head. When I removed it and looked underneath, the bottom of the third cylinder was covered in oil (see attached photo).

    Is this a result of faulty valve stem seals (and six months of sitting)? Ignorance here, but could this cause a failed ignition coil or be a result of?

    I do not have any idea what automotive machine shop I can bring it to or how to find a good one, I am guessing google is my friend?
    Do I just ask them to inspect it and tell me what is needed i.e. lapping the valves? Is there anything specific I should ask for? Do I provide any of the replacement parts?

    And as bonus question, with the head off, is this a good time to soak the pistons?

    Thank you for any help.
     

    Attached Files:

  2. Tombukt2

    Tombukt2 Senior Member

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    Soak the pistons Do you got the car down this far You might as well take the girdle off the bottom of the oil pan and push the pistons through the top take another two days of your time to tank those put in the new rings supposedly that are available for this setup and all of that. I see this is New Jersey so I'll just leave that you'll be back here in 4 months with well won't be pretty I don't think anyway good luck my friend wow
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Head gasket usually fails at the adjoining wall between cylinders one and two. It could be you’re misreading the appearance, that cylinders three and four are more the usual, while cylinders one and two have been kept clean due to coolant getting past the head gasket.

    The main reason for a machine shop intervention would be to check for and remedy warpage of the machined faces. With a machinist’s straight edge and feeler gauges you can check this yourself. In lieu of proper machinist’s straight edge, it wouldn’t hurt to try with the best you’ve got, say a near-new metal level, slotted-angle or what have you.

    the last link in my signature is the engine section from the repair manual, has the flatness specs. On a phone turn it landscape to see signatures.

    there’s also a couple of head gasket repair links in my signature; the “critic” thread in particular details using a machine shop.
     
    #3 Mendel Leisk, Dec 13, 2024
    Last edited: Dec 13, 2024
  4. ASRDogman

    ASRDogman Senior Member

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    How many miles on the engine? That's important. How often have you changed
    the oil? 5000 or 10,000 miles? It looks like it's burning oil, a lot.
    Don't let anyone fool you into believing "soaking" the pistons will help.
    The very LEAST you should do is remove the pistons, remove the rings, clean them and
    clean the piston grooves. 2nd best is to replace them with the updated versions.

    But, before this, look at the cylinder walls, is the wear even?
    If parts of the wall looks different, it's likely that the cylinders are no longer evenly round.
    You could get a 3 sided hone and do a light honing and HOPE it's enough to clean them up.
    But, it's probably time for a remanufactured engine. Hydrid Pit has them starting at $2000.

    You could get by with a short block from Toyota, about $2000.
    You can check for leaking valves, clean the head and valves, then dry the head/valves.
    Then lay it flat and spraywd40 or other light oil in each valve, intake/exhaust.
    Wait about 10 minutes. The tilt the head up and look for leaking valves. If any are leaking,
    you have to seat in the valves.
    And change the valve guide seals since you have the valves out.

    A lot depends on your finances. And what you want your daughter to have.


     
    #4 ASRDogman, Dec 13, 2024
    Last edited: Dec 13, 2024
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Toyota offers a gasket kit, has head gasket and all the seals, including valve stem seals. Attached has some part nos, that kit, and revised pistons/rings.
     

    Attached Files:

  6. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Finding good machine shops isn't that hard- ask how long they've been in business.

    Bad ones do not survive long.