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Strange noise under full boost

Discussion in '4 Cylinder' started by US Marine, Mar 3, 2018.

  1. Mar 3, 2018 at 12:57 AM
    #1
    US Marine

    US Marine [OP] Semper Fi

    Joined:
    Mar 24, 2016
    Member:
    #182227
    Messages:
    14,023
    Gender:
    Male
    First Name:
    Chuck
    SoCal High Desert
    Vehicle:
    02 Pre Runner supercharged 4cyl
    TRD supercharger , Doug Thorley header , K&N CAI 265/75-16 Toyo open country mud terrain , 15x8 Method Racing wheels , Rancho 3" lift , 4.88 gears , Detroit Locker
    My 02 Tacoma is running a TRD Black case low boost 4.5psi supercharger which is a Eaton M68 model

    The engine only has 65k miles and the supercharger has about 40k on it . A couple weeks ago I started hearing a groaning sound under full boost only and can be heard inside the truck with windows rolled up . I had the serpentine belts replaced last year with maybe 3k miles on them

    Noticed the belts looked slightly glazed and some abnormal wear on them so today had them changed again along with the tensioner and idler pullies . The mechanic said the belt was slipping because of both pullies not keeping tension on the belt and both pullies were in need of replacement

    On the drive home I had no issues with the belts or pullies and was feeling good that the problem was solved . I then head up a steep hill and while under boost the groaning sound reappeared . once I crested the hill the noise stopped


    So what is making this noise ?? , I've checked the supercharger with a engine stethoscope at idle and no abnormal sounds can be heard
     
    Last edited: Mar 3, 2018
  2. Mar 3, 2018 at 1:38 AM
    #2
    US Marine

    US Marine [OP] Semper Fi

    Joined:
    Mar 24, 2016
    Member:
    #182227
    Messages:
    14,023
    Gender:
    Male
    First Name:
    Chuck
    SoCal High Desert
    Vehicle:
    02 Pre Runner supercharged 4cyl
    TRD supercharger , Doug Thorley header , K&N CAI 265/75-16 Toyo open country mud terrain , 15x8 Method Racing wheels , Rancho 3" lift , 4.88 gears , Detroit Locker
    Doing more research , could I have a bad bypass valve ??
     

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