Timing chain slipped with cover off, how do I safely align?

Discussion in 'Gen 3 Prius Main Forum' started by taupehat, Jul 5, 2021.

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  1. taupehat

    taupehat Junior Member

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    Was nearly buttoned up, found a 12mm bolt, thought perhaps it might be the timing chain guide. It wasn't but that's not currently important. I went to double-check the timing and the damn left hand guide popped off and the chain jumped and I think one of the camshafts may have turned.

    Below are the positions of all three sprockets. How can I safely get this back into alignment from here?
    [​IMG]
    [​IMG]
    [​IMG]
     
    #1 taupehat, Jul 5, 2021
  2. PriusCamper

    PriusCamper Senior Member

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    I don't have much experience with this stuff, but I'm not seeing evidence that timing marks are no longer lined up? Maybe someone else will come along to comment/clarify.
     
    #2 PriusCamper, Jul 5, 2021
  3. taupehat

    taupehat Junior Member

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    I had the idea of taking the chain off and using the paint marks to see if the cams were at least in alignment, but they were not.

    I'm guessing the next step is let the cam bearings up, rotate them and the motor to TDC, and then bring the cams back down. Tricky figuring out what TDC is supposed to be but I can get a close approximation from the painted links on the chain maybe? All help welcome - this job just went totally pear-shaped on me.
     
    #3 taupehat, Jul 5, 2021
  4. PriusCamper

    PriusCamper Senior Member

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    yeah, definitely spend lots of time checking and re-checking before you address. If it's off its only slightly off and the less you adjust it the more likely you'll be successful.
     
    #4 PriusCamper, Jul 5, 2021
  5. ASRDogman

    ASRDogman Senior Member

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    Take the chains off, plugs are out, right?
    Then rotate the engine slowly until the pistons are away from tdc. Then rotate the cams
    to the respected places. Then rotate the crank to TDC for #1 piston.
    Install the chains. Though I don't think it matters where the chain for the oil pump goes.
    I am not certain about that, I've never seen anyone write about it.
     
    #5 ASRDogman, Jul 6, 2021
  6. ChapmanF

    ChapmanF Senior Member

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    It's the keyway on the crankshaft itself that you want to rely on for knowing where TDC is, given that you don't necessarily trust the chain position.

    I've made jokes before about why the oil pump drive would also have timing marks, but I don't really know. I've read about other engines, like the Mitsubishi ones with balance shafts, where that chain also kept the balance shafts properly timed to the crank. But as far as I know, this engine just has a little oil pump in front, and I don't think those affect balance much. But what do I know, it's got timing marks, and the manual even specifically mentions them, so maybe there really is some reason.
     
    #6 ChapmanF, Jul 6, 2021
  7. taupehat

    taupehat Junior Member

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    Looking at it closely I realized there was no real need for panic - the valves and crankshaft were all very close to TDC, so I used the painted links on the chain to get the valves aligned, then about a quarter turn on the crankshaft and Bob's your uncle. Engine is looking much better now :)
    [​IMG]
     
    #7 taupehat, Jul 6, 2021
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  8. ASRDogman

    ASRDogman Senior Member

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    Glad it was simple for you! Have you started it???

     
    #8 ASRDogman, Jul 7, 2021
  9. privilege

    privilege Active Member

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    does it run now?
     
    #9 privilege, Jul 7, 2021
  10. taupehat

    taupehat Junior Member

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    I'll find out today. Was waiting for the Permatex to dry and also ran out of light before I could get the dust cover and splash guard buttoned up. Fingers crossed.
     
    #10 taupehat, Jul 7, 2021
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  11. taupehat

    taupehat Junior Member

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    Started, runs, drove around a tiny bit with no issues (need to top up oil and coolant as expected). No codes so far. Phew!
     
    #11 taupehat, Jul 7, 2021
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  12. ASRDogman

    ASRDogman Senior Member

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    That's great!
     
    #12 ASRDogman, Jul 7, 2021
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