2012 Head Gasket Replacement - Timing Chain Tensioner won't insert

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Chase B, Apr 9, 2026 at 9:33 PM.

  1. Chase B

    Chase B Junior Member

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    2012, 249k miles, attempting to do a head gasket replacement on my own. Things have gone...mostly OK, but I am at the point where I am trying to re-insert the timing chain tensioner and it will not insert. When putting my fingers through the hole it feels like there is not enough room for the locked in place tensioner to insert, and I'm wondering if the plastic chain guide is blocking it, as I can certainly feel the chain guide with my finger when inserting into the hole. I'm more than a little worried the tensioner guide is not seated correctly. Has anyone had this issue, and if the chain guide isn't seated correctly is there any other option other than taking apart the timing chain cover and starting over from that point? I'm confident the chain guide was inserted into the hole at the bottom, but there were times when it would shift to the left (although I didn't think it did before I put the cover on).

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    #1 Chase B, Apr 9, 2026 at 9:33 PM
    Last edited by a moderator: Apr 10, 2026 at 1:41 PM
  2. CR94

    CR94 Senior Member

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    Is there a chance that's due only to tension on that side of the chain, which you could relieve by pushing on it or by rotating the crankshaft forward slightly?
     
    #2 CR94, Apr 10, 2026 at 8:36 PM
  3. NutzAboutBolts

    NutzAboutBolts Senior Member

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    When the timing cover is mounted back up, the chain slipper hugs tight enough on the chain and you can insert the chain tensioner back in. The slipper doesn’t have any room to obstruct the chain tensioner being inserted once the timing cover is back in.

    if you still can’t fit the chain tensioner back in. Remove the timing cover and redo the rtv/fipg seal but this time, use mechanic wires to hold the slipper and chain in place against the top of the chain so it doesn’t slip to the left.
     
    #3 NutzAboutBolts, Apr 10, 2026 at 11:33 PM
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