valve stem seal DIY

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Mola, Apr 6, 2018.

  1. ChapmanF

    ChapmanF Senior Member

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    I think we keep doing that because Figster tagged onto a thread in the Gen 3 forum rather than starting one in the Gen 2 forum.

    The 1NZ engine has a bunch of boldface notes in the manual about (a) never rotating the crankshaft if the timing chain is out of position, and (b) never rotating a camshaft with the chain out of position, unless the crankshaft has first been turned 40° CCW from TDC. (Which is a little amusing as b contradicts a slightly, but you see what they mean: at 40° away from TDC, all of the piston faces are far enough lowered that it won't matter what the valves do.)

    Of course reinstalling the cams, laying them down on top of the valves and then tightening the bearing caps, which will push down against the springs, is effectively the same as 'rotating' the cams to whatever position they happen to be in as you begin to tighten the caps.

    Then it's important to make sure both cams are at their #1 TDC marked positions, before rotating the crank those 40° CW back to its #1 TDC position.
     
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  2. douglasjre

    douglasjre Active Member

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    I'm getting the same part number for these years....
    3/4th gen have same valve guide seals. But these are diff from 2nd gen. Do 2015, 2016+ also burn oil?
     

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    #82 douglasjre, Mar 29, 2020
    Last edited: Mar 29, 2020
  3. douglasjre

    douglasjre Active Member

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    Also, what do your seals look like prior to prying them out?
     
  4. douglasjre

    douglasjre Active Member

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    BTW: Judging by how much oil on the intake valves I believe you are onto something....
    Anybody here have pix of clogged oil scraper piston/ring combinations?
     
  5. Figster10

    Figster10 Member

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    I'll be trying that out tonight hopefully it works. I'm pretty sure that could be what's missing since it wont even turn at all with everything TDC.
    Posted via the PriusChat mobile app.
     
  6. ChapmanF

    ChapmanF Senior Member

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    I have some concern that, if that was the explanation, all might not be made well again just by saying "oops, didn't mean to do that" and trying it the other way.
     
  7. Figster10

    Figster10 Member

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    In mechanic terms please.... we are just trying to figure out a timing chain situation
    Posted via the PriusChat mobile app.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Well, if the difficulty turning the crankshaft so far turns out to have resulted from cranking cam bearings down while valves were mispositioned with respect to pistons below them, it is possible that anything bent or damaged during that experience might not magically become unbent and undamaged just by backing up and trying again the right way.

    I'm not saying that as a certainty, only as a possible disappointment to be prepared for.
     
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  9. Figster10

    Figster10 Member

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    I am prepared to remove the head as a worse case scenario. I am aware of the 40 degree turn which is something I didnt try so if that doesnt work then I will proceed to removing head even though I'm hoping that is not the case
    Posted via the PriusChat mobile app.
     
  10. telmo744

    telmo744 HSD fanatic

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    This is a very very interesting thread. Any news on this subject? (y)
     
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  11. ASRDogman

    ASRDogman Senior Member

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    Any update on fixing your problem????
     
  12. douglasjre

    douglasjre Active Member

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    If you wanna replace guide seals w/o pullin ghead hook up compression tester hose to air compressor tank....
     
  13. douglasjre

    douglasjre Active Member

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    You gotta spend money on tools, and lots o them. To work on someone's o/b boat motor I told him to buy the dealer computer and cables. He balked about the $59 price. I asked how he felt about replacing the ign sw and fuel pump with the wrong parts and paying $120 to get the wrong parts only to have to bring it to me and pay me to put it all back together...and still need the computer. You decide. Buy tools my friends and lots of them. I have at least two of everything at this point. One compression set has a 1/4" fitting. I reserve it just for what you're doing right now
     
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  14. telmo744

    telmo744 HSD fanatic

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    So the rope option is no good? With compressed air we don't have to rotate the crankshaft?
     
  15. douglasjre

    douglasjre Active Member

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    U won't bend valves cus w both cams removed all valves will b closed....b sure to time motor b4 installing cams

    I've never done rope. As a mechanic I used the technique I spoke of here. Did it on a boxer Moto w valves that greet the piston head on. Maybe it was a Kohler twin....used to rebuild those w new piston and rings and reply crankshafts while motor still installed In unit
     
    #95 douglasjre, May 30, 2020
    Last edited: May 30, 2020
  16. douglasjre

    douglasjre Active Member

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    This is your first time cracking open a valve train huh
     
  17. telmo744

    telmo744 HSD fanatic

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    I've never done it, just thinking of doing it in a '93 Toyota Carina 4A-FE. And curious if it is a pratical solution to perform in a 2ZR-FXE.
     
    #97 telmo744, Jun 1, 2020
    Last edited: Jun 1, 2020
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  18. T1 Terry

    T1 Terry Active Member

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    The major problem is stopping the crankshaft from turning. If the cyl you pressurise has the piston at the bottom of the stroke then the crankshaft won't move, but a few degrees either side is enough to cause the crankshaft to turn because the piston is being forced down.
    The tricky part when using compressed air is testing the valve guide wear once the spring and seal has been removed. Drop the air pressure off and push the valve down a bit so it is no longer on the valve seat, but don't let it fall all the way through so you don't have enough valve stem available to pull the valve back against the seat while you reconnect the air pressure. I always slipped a slightly smaller diameter "o" ring over the valve stem so it wouldn't allow the valve to fall all the way through if some clown disconnected the air line at the wall or turned the compressor off because it was annoying them or they can't hear on the phone ..... yes, worked with both these types of morons .....
    The rope trick is much slower and a bit more of a pain to get the valve to stay all the way up while you get the valve collets back in place, but less chance of the valve dropping through the valve guide resulting in the head removal after all.

    I still have my doubts about the valve stem seals being an issue unless the engine was over heated to the extreme, the head would be warped then anyway, or the oil was rarely changed. There is a lot of oil splashed around the cam lobes and therefore on the valve stem and seal cooling them while lubricating them.
    My '08 ex taxi Prius has close to 730,000km on the clock now, you would expect the valve seals to be disintegrated by now if hardening of the rubber did occur, yet it uses less oil than my '06 Prius with much lower mileage on the clock.

    T1 Terry

    T1 Terry
     
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  19. ASRDogman

    ASRDogman Senior Member

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    If you put the piston at top of the stroke, the valve cannot fall into the cylinder.
    No compressor or rope needed.
    Valve guild seals do get hard and allow oil to be sucked into the cylinder. Every engine is
    different so some will allow more oil to pass than others.
    With a 4 cylinder engine, once you put the piston at the top, you'll have another piston at
    the top. You do those seals first. Then rotate the crankshaft until the other two are at the top.
    Then put the #1 piston at the top, align the timing mark and then the put the cams back and install the chain.
     
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  20. SFO

    SFO Senior Member

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    Any updates?
     
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