All of my brand new bolts stretched

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Higgins909, Jul 8, 2026 at 12:02 AM.

  1. Higgins909

    Higgins909 Member

    Joined:
    Apr 15, 2018
    287
    71
    2
    Location:
    Texas
    Vehicle:
    2010 Prius
    Model:
    III
    Well, my new cam assembly bolts came in. I'm pretty sure every single one but maybe 3 stretched.

    I made sure I was reading my torque wrench right this time and didn't have any problems with the timing cover bolts.

    It's the 17 "gold bolts" for the cam assembly. 90105-08455 is what I bought as a replacement. Turns out it's 16 of those and 1 is a short bolt. It's 20ft lbs, right? I don't understand what I'm doing wrong.

    I worked them snug, because there is the valve springs pushing the assembly up. Then I did the bolt pattern to 10#, I noticed it was a bit off. I assumed it was the RTV squshing. Then I worked in 20#, same thing. It would click and I'd go to click it again and it would turn 1/8-1/4 turn more before clicking. I couldn't get a solid stiff click from the majority of the bolts. One started to keep going without clicking, so I took it out.

    Picture, left to right. Old good bolt, old stretched bolt, new stretched bolt. The other picture shows the stretched to the brand new. From under the bolt head, they measured, 2.750", 2.853", 2.806".

    I don't understand what I'm doing wrong.

    2010 Gen3, 223k miles.

    gWGPZB4T.jpg CrV1_BED.jpg
     
    #1 Higgins909, Jul 8, 2026 at 12:02 AM
  2. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    10,979
    6,885
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    My guess is your torque wrench is not calibrated anymore. Do you reset it to zero before storing it?

    Not sure I would worry about on the cam assembly. However the head bolts are another story.
     

    Attached Files:

    #2 rjparker, Jul 8, 2026 at 12:18 AM
    Mendel Leisk likes this.
  3. Higgins909

    Higgins909 Member

    Joined:
    Apr 15, 2018
    287
    71
    2
    Location:
    Texas
    Vehicle:
    2010 Prius
    Model:
    III
    I always zero it out. I had no problem doing the timing cover bolts/water pump afterwards. Nice firm, repeatable clicks at the torque. 19#, 38#. I also redid the exhaust manifold nuts. 15# iirc.
     
    #3 Higgins909, Jul 8, 2026 at 12:22 AM
  4. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    8,025
    4,072
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    Are you certain you have FT lbs? And the correct torque?
    Perhaps it's INCH lbs and not FT lbs?
    I honestly don't remember which it is. I know they are not very tight.
    Also, make sure you are NOT reading "NM".
    Because 1.1 NM, is 10ftbs. So 20NM, would be about 220 ftlb's. image0.jpeg


    image1.jpeg

    I don't believe the cam bolts are stretch bolts. The head bolts are.

    Tighten them down by hand, or hand held socket. Follow the sequence pattern.
    You can push down on the section of the cam that the spring is holding up.
    After they are hand tight, the cam caps should be flat against the head. I would say maybe
    1/2 turn is all the bolt would move with the correct torque.
     
    #4 ASRDogman, Jul 8, 2026 at 7:25 AM
  5. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    10,979
    6,885
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    The spec is Torque: 27 N·m (275 kgf·cm, 20ft·lbf)

    1 NM is 0.7376 ftlbs
    20 NM IS 14.75 ftlbs which is reduced torque.

    Use of oil on the threads can cause stretching even though the torque wrench indicates 20 ftlbs. Most Toyota torque specs are for clean and dry threads except for the head bolts where a specific lubricant is recommended.
     

    Attached Files:

    #5 rjparker, Jul 8, 2026 at 8:23 AM
  6. Higgins909

    Higgins909 Member

    Joined:
    Apr 15, 2018
    287
    71
    2
    Location:
    Texas
    Vehicle:
    2010 Prius
    Model:
    III
    I’ll have to look at my old ones and pull a couple of the new ones out. See if they’re dirty. The new one in the pic has what I think is RTV around the middle of the thread.

    Is that’s causing the stretch? What can I do about this? How do I prevent RTV from getting in, in the first place?

    But still had zero issue with the timing cover. Half the bolts were slathered in old RTV.
     
    #6 Higgins909, Jul 8, 2026 at 9:25 AM
  7. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    8,025
    4,072
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    See Post #4....

     
    #7 ASRDogman, Jul 8, 2026 at 9:42 AM
  8. CR94

    CR94 Senior Member

    Joined:
    Dec 2, 2014
    2,815
    1,235
    0
    Location:
    Northwestern S.C.
    Vehicle:
    2011 Prius
    Model:
    Two
    1.1 NM = about 10 INCH-pounds.
     
    #8 CR94, Jul 8, 2026 at 10:45 AM
(You must log in or sign up to post here.)