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Intake valves .001" too tight - worth adjusting?

Discussion in 'Gen 2 Prius Technical Discussion' started by jeremy3s, Aug 17, 2019.

  1. jeremy3s

    jeremy3s Junior Member

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    I pulled the valve cover off my 2nd gen to replace the gasket since oil was leaking in the spark plug holes. While I was in there, I decided to check valve clearance. I found 4 of the intake measurements to be tighter than spec. Each of the 4 measured 0.006" while spec is .007-.009".

    Is .001" too tight worth the time and effort to adjust them into the proper range?
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    How many miles? And was it stone-cold?

    Here's some repair manual excerpts. I haven't really looked close; if there's more you need let me know, I could look some more:
     

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    #2 Mendel Leisk, Aug 17, 2019
    Last edited: Aug 17, 2019
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  3. TMR-JWAP

    TMR-JWAP Senior Member

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    You could probably have 10 people check clearance and you would get 7 different answers. For situations like this, a good friend once told me....

    IIWW, LITFA

    If It Was Working, Leave It The Xxxx Alone..............
     
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  4. bisco

    bisco cookie crumbler

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    hey, if you're already in there, why not?
     
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  5. TMR-JWAP

    TMR-JWAP Senior Member

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    Yeah....kind of like, since I have the refrigerator door open to get a drink, I may as well make a sandwich. Just maybe a thousand times harder....and a single stupid (or unlucky) move could put the car OOC for a week or more......:whistle:
     
  6. bisco

    bisco cookie crumbler

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    true but it is out by .001. that's nothing to sneer at. and what's wrong with a sandwich?
     
  7. ChapmanF

    ChapmanF Senior Member

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    Gen 2 has the 1NZ engine. Here's a post to give you an idea of the process for adjusting 1NZ valve clearance.

    You can replace the engine with a lower-mileage one in a fraction of the time and effort.
     
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  8. bisco

    bisco cookie crumbler

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    but what a great learning opportunity
     
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    It's a far-cry from the screw and lock nut adjusters on Hondas, pretty much a top-end tear-down.
     
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  10. bisco

    bisco cookie crumbler

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    i spent a lot of time adjusting my '74 fiat valves. it's an experience of a lifetime
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Simple adjusting screws?

    With our old Accords, the valve cover was very accesible: take off it's hold-down bolts, disconnect a hose or two, pry a bit, and you're there.

    Then get out eh Shop Manual, and put a ratchet and socket on the crankshaft, through the wheel well.

    With the screw and lock-nut adjusters, 2~3 hours is all it would take.
     
  12. bisco

    bisco cookie crumbler

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    lock nuts iirc, it's been 40 years :oops:
     
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  13. sam spade 2

    sam spade 2 Senior Member

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    Well actually it probably IS nothing worth worrying about.

    Being a hair too tight indicates that the valves are seated .001 farther down in the seat than the minimum spec.
    They could have been that way for a LONG time......maybe even since the engine was built.
    It is fairly common for them to tighten up a bit with age......since the valve face and seat usually wears more than the cam lobes and valve stem.

    I vote for leaving them alone.....and checking again in another 50K miles or so.

    Edit: And given what has been said in the last few posts about the procedure necessary, I wouldn't have checked them in the first place.
     
  14. jeremy3s

    jeremy3s Junior Member

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    I decided to go ahead and do the job over the weekend. There was a set of old lifters from a warped head laying around in the garage. Using those, I was able to get all the 4 intake valves in spec. This was my first time doing a valve adjustment on one of these, so I did have to pull the cams a second time to get everything right. In the end i think it was worth it.

    The engine has 292k miles on it, so should be good to go for at least another 100k.
     
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  15. TMR-JWAP

    TMR-JWAP Senior Member

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    IDK what to even say..............I'll make sure to look you up for advice next time I want to make my life 100x more difficult than it needs to be....... ;)

    But...well done..you have my respect for being willing to tackle that job
     
  16. Skibob

    Skibob Senior Member

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    How long did it take you?
     
  17. jeremy3s

    jeremy3s Junior Member

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    I have a habit of making things harder than they have to be. But, I'd say I only made it 10x harder than it had to be. lol
     
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  18. jeremy3s

    jeremy3s Junior Member

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    I'd estimate I spent 10-12 hours working on it. But, I double and triple checked things. This included 2x of pulling and installing the valve cover, the cams, and making sure the timing was right. I also drew pictures, and took a lot of measurements. If it's your first time and you want to start the job on a Saturday and absolutely need the car on Monday, I wouldn't recommend it. If you don't have a set of used lifters available you'll be ordering those on Monday. And even if you do have a set, there's no guarantee you'll be able to get everything in spec with them.
     
  19. bisco

    bisco cookie crumbler

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    i'm not sure, but you may be the first!(y)
     
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  20. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah that's commendable.