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Now what? (CAM broke off)

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  • Now what? (CAM broke off)

    Just wanted to share my find last night.

    Two weeks ago I've replaced an old KA24DE in my S14 with an OEM Rebuilt one. 500 miles into a break-in, it refused to start so I did a compression test (after making sure that I had A/F/S). The results were painful to see 0 0 0 60.

    I'll let the pictures tell the rest of the story:






    And as if the car thought that breaking the CAM was not enough to ruin my night (what's missing is somewhere in my engine):



    Just sold my SR swap right in time as well

  • #2
    There's your problem!


    That sucks.. I always thought the KA timing chain setup looked like it was putting a lot of stress on the cam.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


    DefSport Koni Sleeve and Spring Perch Buy!!!
    http://www.nissanroadracing.com/showthread.php?t=5902

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    • #3


      Too much timing chain tension maybe?

      Wonder if it bent any/all of the valves? (have to put a new cam in and check it..)

      Who did the rebuild?

      I think I still have a set of OE S14 cams in the garage if you need them, but they might be a touch rusty from the Houston humidity.
      Originally posted by SoSideways
      I don't care what color they are as long as they are LONG AND HARD.
      '04 G35 Sedan 6MT- The DD
      '96 240SX- The Track Toy

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      • #4
        Originally posted by Matt93SE View Post


        Too much timing chain tension maybe?

        Wonder if it bent any/all of the valves? (have to put a new cam in and check it..)

        Who did the rebuild?

        I think I still have a set of OE S14 cams in the garage if you need them, but they might be a touch rusty from the Houston humidity.
        As in upper chain tensioner is too tight?

        About to go pick up another CAM from a friend. But thank you for the offer.

        A friend of mine rebuilt this motor. I know it's got new rings, gaskets, and bearings. Do not know what else was done during the rebuild.

        What I am going to do is pull the oil pan and front timing cover to clean everything out. Then install another CAM and hope for the best. Unfortunately I don't believe that a camshaft would just break. It's got to be either warped camshaft, warped head, or some kind of oil/heat issue. Or maybe something else I didn't think of.

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        • #5
          Was the bolt under torqued? On SR's it's like 100 ft-lb I think.
          '18 Chevrolet Volt - Electric fun hatch for DD duty!


          DefSport Koni Sleeve and Spring Perch Buy!!!
          http://www.nissanroadracing.com/showthread.php?t=5902

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          • #6
            Given the location of the break, it makes me wonder a couple things.. 1. was the cam bolt OVER torqued, causing cracking in the end of the cam.
            2. the cap at the end of the head could be off/wrong/backwards, which caused some strange loading and possibly binding on the cam. however, the wear on the inside of the cap doesn't look abnormal so I tend to think this isn't the issue...

            just random thoughts from a guy that's built 3 engines in the last 20 years. it's worth what you paid for it.
            Originally posted by SoSideways
            I don't care what color they are as long as they are LONG AND HARD.
            '04 G35 Sedan 6MT- The DD
            '96 240SX- The Track Toy

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            • #7
              Looks under torqued due to the failure happening around the root of the keyway. If I was looking at it in person I could maybe tell which part failed first due to the presence of fatigue beech-marks. The back end of it failed due to torsion tho, so definitely while it was spinning.
              '18 Chevrolet Volt - Electric fun hatch for DD duty!


              DefSport Koni Sleeve and Spring Perch Buy!!!
              http://www.nissanroadracing.com/showthread.php?t=5902

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              • #8
                I know on the SRs it is pretty common to break the camshafts by over torquing the caps. They are surprisingly low torque specs 6.7 to 8.7 ft-lbs. Also the order you torque them is important.
                Chicago Region SCCA SM # 688 http://www.scca-chicago.com
                TSSCC SM # 688 http://www.tsscc.org

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                • #9
                  To me it looks like it failed at the dowel, and then radiated back towards the oil hole... if that's the case, it's likely because the chain was going one way, and the cam tried to go the other way

                  Pull the head, tell us what you find, carnage is always awesome to look at :P
                  http://responsetype.com/shop/

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                  • #10
                    Slapped another intake CAM on and got very sad compression results: 0 80 80 15

                    Also discovered that my upper bolt on upper chain tensioner was broken off inside the head. Thankfully, I extracted the remains without too much trouble.

                    Talked to the engine builder - he will be taking partial responsibility for it. He's going to pull the engine out and do the work as long as I can figure out head situation. Tomorrow I am going to pull the head of my spare KA (unknown head condition) and hopefully have enough valves to make one good head out of the two.

                    Will update with pictures once I tear into the motor.

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                    • #11
                      Keeping the same pistons? They might be ok. If not I can probably help you out there for aftermarket.
                      '18 Chevrolet Volt - Electric fun hatch for DD duty!


                      DefSport Koni Sleeve and Spring Perch Buy!!!
                      http://www.nissanroadracing.com/showthread.php?t=5902

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                      • #12
                        Originally posted by Def View Post
                        Keeping the same pistons? They might be ok. If not I can probably help you out there for aftermarket.
                        Depends on the damage, but I am planning on keeping same pistons/rods/rings. Come up with new head/cams, clean the motor, and check bearings - is the plan for now.

                        Either that or use my 80000 miles KA out of my Kouki which is awaiting LS swap. But then I'll have to daily drive my race car until the swap is done. Decisions-decisions..

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                        • #13
                          If worst comes to worst I have several KA heads in Cali...PM me if you can't find one locally, I feel like they aren't worth shipping cross continent.
                          I am SKULLWORKS

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                          • #14
                            Originally posted by Tower240sx View Post
                            If worst comes to worst I have several KA heads in Cali...PM me if you can't find one locally, I feel like they aren't worth shipping cross continent.
                            I am moving to Cali next year, will keep you in mind

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                            • #15
                              Finally got to pulling the motor and tearing it down. My finds are shocking and contradictory considering that this is a 500 mile motor. I apologize for crappy quality pictures - phone camera is all I had at the time.

                              The valves did not look like they've hit anything, but it does look like they might have been sticking due to the build up causing low or no compression on the cold engine.

                              The chassis sat for five years until I bought it. It had about quarter of the tank when I got it. I've replaced following items: in-tank fuel lines, fuel pump, fuel filter, and of course the engine. Then, I've filled it up with good gas (Shell). Also, I've put my hand down the tank to make sure there was no solid contamination on the bottom.

                              I don't believe snapping my cam could have been caused by the build up you see in the pictures. Coincidence?

                              My plan is to take the head to the machine shop, hot tank it, pressure check, and resurface (if needed). Hopefully it's still good. Not so sure on how to prevent future build up from potentially bad gas though. Fuel cell sounds like a good option at this point to eliminate a possibility of this happening in the future.

                              What do you think NRR?

                              P.S. Photos do not give the justice to how nasty the build up really is.
                              Attached Files

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