Oil pressure & turbo boost

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by Ron Sillaman, Apr 7, 2021.

  1. Ron Sillaman

    Ron Sillaman New Member

    5
    Aug 31, 2020
    Annapolis, MD
    2007 40 Sundancer
    Cummins QSB 5.9 380 hp
    Took possession of a 2007 Sundancer 40 with QSB 5.9 380 hp in December. Engine survey was excellent. Launched boat in March. First few times out engines performed perfect. Last time out the port engine oil pressure read 6 or 7 psi less than starboard engine. Turbo boost also was reading less. Any suggestions? Boat ran fine. Analog readings on dash and vessel view numbers matched
     
  2. Shaps

    Shaps Well-Known Member GOLD Sponsor

    966
    Nov 4, 2019
    Long Island,NY
    2010 Sundancer 500
    2015 Brig Falcon 330T
    Twin Cummins QSC550 DTS w Zeus
    FWIW,
    i always have between 6-8 psi difference between my engines.
    It was explained to me that is caused by the extra hosing required to relocate the oil filter on one of the engines.
    As long as it remains consistent i think you are ok.
     
    TNT8808 likes this.
  3. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    12" Axiom and 9" Axiom+ MFD
    Cat 3126 V-Drives
    How far off was your turbo boost? A psi or two could be guage error, or a conversion error if reading g digital, or a combination of the two.
     
  4. LG111

    LG111 Active Member

    644
    Jan 4, 2015
    NW
    44 Sedan Bridge - 07
    Black Hull
    QSC500’s
    Try this, sometimes the system glitches. Turn the keys or switchs to ignition but not starting. Pause for 15 seconds or at least until the computer is fully up and running. Then start the starboard first then Port. See if boost matches. Oil pressure will always very between engines.
     
  5. Ron Sillaman

    Ron Sillaman New Member

    5
    Aug 31, 2020
    Annapolis, MD
    2007 40 Sundancer
    Cummins QSB 5.9 380 hp
    Followed your advice. Readings were opposite. Starboard engine was showing lower oil pressure and lower turbo boost.. How do you fix?
     
  6. LG111

    LG111 Active Member

    644
    Jan 4, 2015
    NW
    44 Sedan Bridge - 07
    Black Hull
    QSC500’s
    How much lower between turbos? My oil difference is around 56 and 48 at cruise always been that way.
     
  7. LG111

    LG111 Active Member

    644
    Jan 4, 2015
    NW
    44 Sedan Bridge - 07
    Black Hull
    QSC500’s
    If pressure is a wide gap between boost, then look into the waste gate.

    A wastegate is a valve that controls the flow of exhaust gases to the turbine wheel in a turbocharged engine system. ... The primary function of the wastegate is to regulate the maximum boost pressure in turbocharger systems, to protect the engine and the turbocharger.
     
  8. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    12" Axiom and 9" Axiom+ MFD
    Cat 3126 V-Drives
    If your boost is off, you will notice other problems. Likely lower power, and black smoke coming from lower boost engine. Any other symptoms?

    The easiest way to confirm is get a good set of mechanical gauges on the engines and measure the boost. You can determine if it’s in spec, and also confirm if it’s gauge error.

    While your down there inspect and hoses, pipes and clamps from the turbo outlet to the manifold.
     

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