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head bolt torque specs on modified engine .

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  • head bolt torque specs on modified engine .

    what are people with modified engine torqueing there head bolts too ? i just recently replaced my engine and put new head gaskets in and torqued to about 47ft lbs as per the chilton manual . i have about 400 miles on the engine and anything over 15 psi of boost , i catch a whif of antifreeze . i popped the radiator cap off and it looks like there is a bit of an oily type of shine to it ., kind of like a drop of oil in a puddle . the only thing i could come up with is under boost i have alittle combustion creeping past a head gasket ring and into the cooling system.


    boost. does a body good!

  • #2
    I would say that a compromised gasket is a compromised gasket.

    I trust that you used an actual Nissan gasket in there, correct?

    When putting mine together, we went +10 on the head bolts....
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports

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    • #3
      Yeah, usually once a seal ring blows out and starts leaking, nothing will stop it. That's not to say it's blown out though. If the head bolts are torqued too low or have loosened slightly (happens on some engines) then it may leak. I had something similar randomly happen on the front half of the passenger side head, they were all torqued to stock when I put it on, but very much loose when I pulled it off.

      First, go back and check the head bolt torque. I torque mine to 54-57lb/ft ever since I had those loosen on me and have not had an issue.

      If it's oil leaking into a water passage that would be somewhat starange... did you prep both surfaces well before installing the gasket and head last time you did it?

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      • #4
        that reminds me.

        I used these on every surface that I could ;D They're wonderful for taking gasket surfaces down to bare, clean metal.

        http://store.summitracing.com/partdetai ... toview=sku
        vg33et -blew some chunks outta it, then gave it all away.
        2009 370z touring/nav/sports

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        • #5
          of coarse i used a felblow gasket set . thats just more reason to worry now that i know thats the nick name everyone gave them. its not oil thats in the antifreeze it's just a very and i meen very light rainbow looking film on the top of the water which i kind of thought would come for combustion gases making it's way into the system. and before i installed the heads everything was spotless.


          boost. does a body good!

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          • #6
            Maybe you're smelling it because it's pushing out into the overflow tank?


            have a compression tester?
            Attached Files
            vg33et -blew some chunks outta it, then gave it all away.
            2009 370z touring/nav/sports

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            • #7
              the tank has very little fluid in, it's just below the max line which means there alot more room for antifreeze to go. the level never changes and i also put a new 16 lb rad cap on to see if pressure was just bypassing the cap . i don't have a good compresion tester but that is my next step after torqueing the heads to about 57 ft lbs to see if that changes anything . i doubt it will but it's worth a shot before i tear the motor out .


              boost. does a body good!

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              • #8
                Does your tq wrench test 'take-off' torque too?

                I'd set it a few lbs below where they should be, and see if it clicks... just to see if they've loosened.

                Other than that, yeah, try another 10..
                vg33et -blew some chunks outta it, then gave it all away.
                2009 370z touring/nav/sports

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                • #9
                  jjewell wrote: of coarse i used a felblow gasket set . thats just more reason to worry now that i know thats the nick name everyone gave them. its not oil thats in the antifreeze it's just a very and i meen very light rainbow looking film on the top of the water which i kind of thought would come for combustion gases making it's way into the system. and before i installed the heads everything was spotless.
                  The guy I bought my 87T off of replaced the head gaskets on the 38K mile engine he put in with felblow. One was blown within like two months, he tore it down and then lost motivation, so I guess I have felblow to thank for getting me such a hella-deal on that car

                  Then again, the other side blew on the trip back home after I had replaced the blown one and re-assembled the engine. GRRRRRRRR.

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                  • #10
                    you know, someone gave me an entire "felblow" engine gasket set for free. guess i know why now. good thing I havent used them yet.
                    1984 300zx Ae Turbo(under repair...)
                    1989 240sx rb20(daily driver)

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                    • #11
                      yeah, i heard not so great things about those

                      Terrible idea putting those wheels on...

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