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Head Gasket Tips

Discussion in 'Gen 3 Prius Main Forum' started by jumpinjivinjoe, May 14, 2020.

  1. jumpinjivinjoe

    jumpinjivinjoe Junior Member

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    At 240,000 miles, my 2010 Prius blew it's head gasket. Ever since I got the car at 190,000 miles it had an occasional rattle shake knock during startup after sitting for awhile. Sometimes I would get a cylinder misfire code. This is indicative of coolant seeping into cylinder.

    I never got a definitive confirmation of head gasket failure though. No coolant in my oil. No oil in my coolant. And nothing out of ordinary after video inspection of cylinders.

    Well one day, I started it up, got a thunk, lack of power, "check hybrid system" screen, and white smoke out the tailpipe. It was finally time to replace the head gasket. I didn't even need to get it inspected. I knew. I put it on a trailer to tow back to my house. Driving it any further in that condition will likely cause irreparable damage.

    I was able to replace the head gasket in two days.

    Here are some tips for other people...

    • Drain coolant and engine oil.
    • You will need to remove pretty much everything from the top and side of the engine. This includes windshield/wiper cowling, EGR assembly, coolant pump, air filter, intake manifold, passenger side engine mount, coolant tank, exhaust manifold, valve cover, spark plugs, passenger side wheel, timing cover, various brackets. (Not in this order).
    • Label all your fasteners.
    • Use impact gun to remove harmonic balancer bolt.
    • Set timing before removing timing chain. Gold links line up with straight marks on camshaft gear. You can lock it in place by clamping a piece of folded paper towel between the camshafts and the part that acts as the bearing/bushing and retains the camshaft with 10mm bolts.
    • Remove head bolts in star pattern starting with outside bolts first.
    • Use razer blade to scrape off most gunk. Then use a red scotch bright pad with velcro backer block to maintain flatness to recondition head and block. Avoid abrasives in coolant and oil passages. Clean with vacuum or compressed air.
    • Check head for flatness with a straight edge and feeler gauge. My understanding with Prius is usually the head remains flat. It's the gasket itself which fails.
    • Spray solvent or gasoline in the intake and exhaust ports once the head is out to look for seepage from the valves. If there is seepage then fix the valve seating issue. I'd suggest just taking to a machine shop if that is the case.
    • Using an abrasive disk, cut a slit lengthwise on one of the old head bolts to chase debris out of the threads in the block.
    • Torque new head bolts to 36 ft pounds, starting in middle head bolts and working way out in star pattern. Then 90 degrees. Then 45 degrees.
    • Use only thin layer of black rtv where needed. Avoid getting it into any oil passages.
    • Use anti-seize on EGR fasteners. Also remove the studs using a female torx socket instead of the regular nut. This is easier for removing and installing the EGR system.
    • If you haven't cleaned your EGR cooler, do it while it's out. It will likely be clogged.
    • Also consider replacing the water pump while this deep because it has been suggested these wear out without warning and can cause chronic overheat issues without driver's knowledge.
    • Change your oil and coolant within the first 200-500 miles of driving it. Sooner if you suspect junk got into it.
    • Also a cordless ratchet makes things faster. A 90 degree angled plier makes removing hose clamps easy.
    • Long handled needlenose pliers are sometimes necessary for removing the socket from spark plug because sometimes the socket gets stuck on the spark plug. down the spark plug tube.
     
    #1 jumpinjivinjoe, May 14, 2020
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  2. jumpinjivinjoe

    jumpinjivinjoe Junior Member

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    Oh and one other thing.

    The unusual tool to get is a 12mm triple square bit for the head bolts. It was challenging to get locally.
     
    #2 jumpinjivinjoe, May 14, 2020
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    I'd respectfully counter with 10 mm double hex. Virtually the same, but a better fit and Toyota recommendation. Same number of points, Very slightly less protruberance, and the kosher 60 degree corners (not 90 deg). FWIW gasket masters uses your bit style, it works.

    I'd second the anti seize on EGR Fasteners. The one on the underside cooler bracket: just leave it off, both the nut and stud.

    Thanks for the post, will read thru it carefully.
     
    #3 Mendel Leisk, May 14, 2020
    Last edited: May 14, 2020
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    A little EGR fastener torque info.

    With clean/dry threads:

    Studs: 84 inch/pounds
    Nuts: 15 foot/pounds

    With anti-seize applied reduce torque by 25%.
     
    #4 Mendel Leisk, May 14, 2020
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  5. Raytheeagle

    Raytheeagle Senior Member

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    Leave off the stud :whistle:?

    Leave the stud as it will brace the cooler a bit:).

    While everything Is secure without the stud there, the stud doesn't offer much resistance to remove;).

    Move onto the gen4 and leave the inverter in place of you want a challenge(y).
     
    #5 Raytheeagle, May 15, 2020
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    I took that lower bracket stud out. Ridiculously tough to turn, all the way out, and with all the cables (even pulled out of the way as much as possible), could only get 3~4 clicks on the ratchet. Didn't want to strip the torx head, so went slow and careful, at least 15 minutes patient work.

    No way I'll reinstall it lol.
     
    #6 Mendel Leisk, May 15, 2020
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  7. Raytheeagle

    Raytheeagle Senior Member

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    Well if you take it out, then no wonder you don't put it back:p.

    Over achiever:ROFLMAO::LOL::ROFLMAO::LOL:.
     
    #7 Raytheeagle, May 15, 2020
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    The other one, that goes through the valve, plus the simple bolt on the top of cooler bracket, are plenty methinks. Those I backed out and applied thin layer of anti seize.

    The disimilar metals at play I think, are causing the resistance.
     
    #8 Mendel Leisk, May 15, 2020
    Last edited: May 15, 2020
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  9. John A

    John A Junior Member

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    You gotta be joking me. i could leave the stud and nut off from the underside. it took me hours and trips to harbor freight trying to get that **** bolt off and torqued down:mad:
     
    #9 John A, Jul 21, 2020
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  10. John A

    John A Junior Member

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    theres 4 studs and 1 nut correct?
     
    #10 John A, Jul 21, 2020
  11. Raytheeagle

    Raytheeagle Senior Member

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    The underside nut is the one I collect;).

    I have about a dozen now:).

    Keep the stud on there for alignment but save the nut the next time you do the job(y).
     
    #11 Raytheeagle, Jul 21, 2020
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    There's this:

    upload_2020-7-21_16-39-58.png

    I'd call it four studs, four nuts (on those studs), and one bolt, up at the top.

    Again, with that hard to reach lower one, I've left the nut off, then went back and removed the stud as well*. Suspect having the latter off might make it easier to disconnect from from the exhaust manifold, next time around, those two back studs can be left alone??

    I removed that stud with everything still in place, and was really stressing that I was going to strip the Torx pattern on the tip. I took it real slow, and it complained till it was practically off.
     

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    #12 Mendel Leisk, Jul 21, 2020
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  13. John A

    John A Junior Member

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    The first time I put it on I was super double guessing myself because everyone said bolts and I only tightened one bolt to 21 or 16lbs. everything else I was like should I tighten it harder
     
    #13 John A, Jul 21, 2020
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  14. John A

    John A Junior Member

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    :p
     
    #14 John A, Jul 21, 2020
  15. johnnychimpo

    johnnychimpo Active Member

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    I shaved the metal around the egr now I can use regular box wrench
     
    #15 johnnychimpo, Jan 11, 2021
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  16. tvpierce

    tvpierce Senior Member

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    I did the same thing. I forgot to put it on when I reassembled everything, then noticed I had this one nut left. There was no way I was going to take the whole thing apart again. So, out came the Dremel, and cut a piece off the flange so I could get at it.(y)
     
    #16 tvpierce, Jan 12, 2021
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  17. machinemanX-S.A.

    machinemanX-S.A. Junior Member

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    Help! Left over skinny 70mm M7 bolt.
    I started a gen 3 head gasket replacement a mon th ago, but had to leave the stae . Now I am back, and whilst putting on the timing cover, I have a cup marked "timing cover" bolts and I can't figure out where this M7x70 goes. I think it is a 10mm head. It is raining now (argh!) so this being Florida, had to pack up and wonder if any of you smart chaps can remember where it goes. To compound matters, I was trying to teach my son some skills, and let him take it off, so was not concentrating. I do not have a manual. Tried to download the one stored on this thread, but have never been successful-Just keeps a little darn wheel turning all night long. Be a pity to put the entire job together only to have to take it apart again. In fact, suicidal lol. Like a monsoon out there. 'Tween this and the mosquitoes, yeech!
    Please give a suggestions if you think of one.
     
    #17 machinemanX-S.A., Jul 19, 2021
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