Replacing Head gasket -inspecting, cleaning valve stems

Discussion in 'Gen 3 Prius Main Forum' started by degreesNORTH, Apr 21, 2022.

  1. degreesNORTH

    degreesNORTH New Member

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    Question- I'm replacing the head gasket in my 2010 Prius. As I clean and inspect the head I am wondering if I need to bother with removing and cleaning the valve stems? They look well seated. If I do remove, do I need to replace the Valve stems seals. I wasn't consuming any oil prior, just the head gasket coolant issue. Once I noticed the engine vibration I stopped on start I parked it until now to replace the gasket. I took time off from work and don't want to wait for shipping on the seals and I don't want to spend the $350 for a machinist. -Thanks.
     

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  2. JC91006

    JC91006 Senior Member

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    Not sure the answer to your question, but looking at your picture, it doesn't look like any coolant was leaking in.
     
  3. Mendel Leisk

    Mendel Leisk Underfoot

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    There's a gasket kit you can get from Toyota that has ALL the pliable bits, including head gasket, and the valve seals. Very prudent to do it all. It's listed in attached pdf. The head bolts are spec'd too: it's prudent to change them as well. They "can" be reused, if they're within specs, but...

    Take a look at the two head gasket links in my signature, in particular the "the critic" one.
     

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  4. ASRDogman

    ASRDogman Senior Member

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    Since you have the head off, replace the valve guide seals. They do get hard and leak.
    Since you are not burning out yet, replacing them would be wise.
    You can rent the spring compressor from autozone or similar place and do them yourself.
    And you could clean up the valve while your at it. Super easy to do while the head is off!

    BEFORE you do that, spray/pour some light oil into each intake and exhaust port, (?table spoon?),
    while the head is sitting with spring up. Wait 5 minutes or so and carefully lift the head and look for
    any oil seeping through where the valves seat. If you see none, you're good. If they are leaking,
    you can get some valve grinding compond and seat them in.

     
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  5. degreesNORTH

    degreesNORTH New Member

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    Thanks all. I'm an idiot and didn't realize my gasket kit came with new valve stem seals. Now the fun part of lapping those begins. :-(
     
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  6. BiomedO1

    BiomedO1 Active Member

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    The safest route is to replace them, while your head is out. You didn't mention how many miles was on it and I tend to be more conservative and don't like doing things twice - if I can avoid it.

    @ASRDogman: neat trick! haven't done that in 30 years; but you do need a put enough oil in to submerge the entire circumference of the valve. Otherwise you may miss some seepage. Obviously dump out the oil, before reinstalling head.
     
  7. Mendel Leisk

    Mendel Leisk Underfoot

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    Gasket masters use a generous shot of brake cleaner IIRC.
     
  8. PriusCamper

    PriusCamper Senior Member

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    Does anyone know of a gen3 that had it's head gasket replaced but not the valve seats that later led to valve work needing to be done? Seems like a lot of work to do all the valves and if the data shows that they continue to be good without being re-done, it's not worth the extra time, right?
     
  9. ASRDogman

    ASRDogman Senior Member

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    I "think" someone from a machine shop said if the oil is too thin, like wd40, it will seep through.
    It's been decades, I just don't remember......
     
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  10. ASRDogman

    ASRDogman Senior Member

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    You're not an idiot. You just didn't know... But now you do.
    Only lap them in IF they are leaking. Toyota does a good job with valves and they last
    a long time. Then them first.

     
  11. edthefox5

    edthefox5 Senior Member

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    I do not know... if it was me I would take it to a machine shop and let them check it. Seen a few failures after HG replace on this site.
    They may find things you had no idea.
     
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  12. rjparker

    rjparker Senior Member

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    Wrong. Lots of head issues are caught at the machine shop.
     
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  13. Classic Car Guy

    Classic Car Guy Active Member

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    I agree...

    To the OP: That's a lot of work leaving it just halfway. Atleast get it magnaflux leak check. flycut surface to minimum and get a set of Fel-Pro gasket. change the valve seals, while youre at it grind the valves even by hand..... LoL...
     
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  14. PriusCamper

    PriusCamper Senior Member

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    I found a machine shop that does engine heads for $50 thus far, but suspect they won't look too close for $50 and most people I've talked to said no need to do that unless pitted.

    What's do ya'll think going rate for entirely tested and inspected head rebuild if you're doing the head gasket part of it?
     
  15. Classic Car Guy

    Classic Car Guy Active Member

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    That's the one thing I don't joke about engines. I always keep the cooling system in tip top shape. 100,000 miles I replace everything down to the waterpump, thermostat, coolant, hoses upper and lower, clamp and clips. I replaced 3 pumps on my '07. I flushed it with distilled water. Its just a fact that the prius doesn't have a gauge for me to monitor the actual temperature. So I wont take any chances.
     
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  16. PriusCamper

    PriusCamper Senior Member

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    Sounds like a huge waste of time and money... Most cars built in last couple decades can easily go 300K miles with nothing more than oil changes and spark plugs, especially hybrid cars that use their gas engine less often than regular cars.
     
  17. Classic Car Guy

    Classic Car Guy Active Member

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    It depends. There are people like myself that are on the go and I cant afford to miss an opportunity in my life same as taking any chance being disabled in mobility.
    There are people that chooses to be behind a computer just typing away their life. and that's not what I do.
     
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  18. degreesNORTH

    degreesNORTH New Member

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    Hey All, Thanks for your input. Put the car back together, did a short prayer, started and after a few minutes she was running nicely. Put about 30 miles on her tonight and so far so good. These forums and resources are invaluable to guys like me. Thanks again!
     
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