Have to tear the motor down for rebuild..

  • grahfz
    grahfz
    Senior Member
    • 310

    Have to tear the motor down for rebuild..

    I've lost ~30psi compression (some worse, some less) across all six… still acceptable compression, but in the little bit of mileage I've put on this motor between tests, not acceptable.

    It's getting lots of blow-by. Smoke coming out of the valve-covers and blowing the dipstick out. I can feel the engine pulsing through the covers as well.

    Burns oil as soon as you start it as well… fouling out the plugs too.

    And it's also developed a rod-knock. pretty badly too.

    All of this is pointing at something in the oiling system, to me.


    so, 15k miles on this engine, and it's down for a rebuild.
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports
  • t70
    t70
    Senior Member
    • 104

    #2
    OUCH!!! That's awfully depressing.. I didn't replace the oil pump in the vg30 when i built it -- hope it doesn't bite me in the ass. I would have replaced it but my poor buddy who owns the car was expecting to spend much much less than he has so far.
    8.5 custom arias pistons (.020 over)
    eagle rods
    t70 turbo (man was that a squeeze)
    38 mm external wastegate
    mild port/polish
    3 angle valve job
    custom intercooler piping
    twin external intakes with z32 maf
    rad moved back
    3" exhaust with only a resonator
    romulator
    420cc injectors
    custom body work, homemade oil lines and fittings..
    walbro 255lph in-line fuel pump.... and lots of headaches… lol
  • G-E
    G-E
    Junior Member
    • 6320

    #3
    how was oil pressure? aside from oiling problems like sludge or blocked passages, was everything cleaned/flushed before?

    there's first of all no way 15k should wear out rings so much to have blowby.... but having excessive blowby does cause a bit of oil cooking, especially where there isn't that much

    also I'd really like to know if you you were running hot/lean
  • grahfz
    grahfz
    Senior Member
    • 310

    #4
    I put a HP/HV pump in it when we built it.

    Oh, I'm adding it up, and I'm going to have another 2-3k in it by the time that I'm done.
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports
  • grahfz
    grahfz
    Senior Member
    • 310

    #5
    G-E wrote: how was oil pressure? aside from oiling problems like sludge or blocked passages, was everything cleaned/flushed before?

    there's first of all no way 15k should wear out rings so much to have blowby.... but having excessive blowby does cause a bit of oil cooking, especially where there isn't that much

    also I'd really like to know if you you were running hot/lean
    not running hot/lean at all. Only 4-6psi of boost w/ a walbro. shouldn't have been a problem, plus I was watching the LM-1.

    Oil pressure, is still well above FSM specs.

    the whole engine was pretty much new.. but yeah, we tore it down and had it cleaned.

    *edit* as an addition.. the compression tester was coming back with good amount of oil on it from some cylinders.
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports
  • BLOZ UP
    BLOZ UP
    Senior Member
    • 2971

    #6
    rings may not have seated right…
    BLOZ UP.com
    It is not recommended to confirm proper installation by driving into walls or other barriers as this could cause personal injury or damage to the vehicle.
  • MrwassmanNA2T
    MrwassmanNA2T
    Senior Member
    • 2319

    #7
    BLOZ UP wrote: rings may not have seated right…
    unfortunatly, sounds like it

    Terrible idea putting those wheels on…
  • grahfz
    grahfz
    Senior Member
    • 310

    #8
    motor was perfect until the upgraded turbo. Hell, during that whole ordeal, I tested compression, averaged ~181psi
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports
  • G-E
    G-E
    Junior Member
    • 6320

    #9
    try nissan rings this time? heh
  • grahfz
    grahfz
    Senior Member
    • 310

    #10
    heh, they were nissan rings.
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports
  • G-E
    G-E
    Junior Member
    • 6320

    #11
    then all I can think is you didn't break it in properly
  • j30_vg33et
    j30_vg33et
    Member
    • 62

    #12
    I've got some spare Total seal rings laying around here for sale… Didn't use them cuz file to fit was just tooooo much of a PITA.
    It's RWD in reverse.
  • t70
    t70
    Senior Member
    • 104

    #13
    it's not that difficult.. i just use a ring file… takes about an hour to do all the rings perfectly. Less time if you've done it before… took me an hour to file fit and assemble the bottom end of a 4g63.
    8.5 custom arias pistons (.020 over)
    eagle rods
    t70 turbo (man was that a squeeze)
    38 mm external wastegate
    mild port/polish
    3 angle valve job
    custom intercooler piping
    twin external intakes with z32 maf
    rad moved back
    3" exhaust with only a resonator
    romulator
    420cc injectors
    custom body work, homemade oil lines and fittings..
    walbro 255lph in-line fuel pump.... and lots of headaches… lol
  • grahfz
    grahfz
    Senior Member
    • 310

    #14
    G-E wrote: then all I can think is you didn't break it in properly
    I'd say ~15k miles is broken in.

    I've got some spare Total seal rings laying around here for sale… Didn't use them cuz file to fit was just tooooo much of a PITA.
    Thanks, but I'll get them with the pistons.
    vg33et -blew some chunks outta it, then gave it all away.
    2009 370z touring/nav/sports
  • j30_vg33et
    j30_vg33et
    Member
    • 62

    #15
    If you call Beeri at Arias he's already got a set of +0.5mm VG33ET 8.5:1 compression forged pistons designed. They use the 21mm stock rod pin diameter too, which is nice. The pins is tool steel, and narrowed for weight.

    On my set, there's never any piston clatter. Also, clearly, I had them coated at Swain, which isn't included in his price.






    It's RWD in reverse.