Fluctuating oil pressure guage

Discussion in 'Sport Cruisers' started by Calmseas, Aug 13, 2018.

  1. Calmseas

    Calmseas New Member

    2
    Aug 11, 2018
    04 Searay Sundancer
    Mercruiser 6.2 mine horizon
    Elbow failure on the port engine caused water to enter the oil. After replacing the elbows and multiple flushing and oil changes, the engine runs perfectly except now the oil pressure fluctuates between 27 psi and 50 psi at 2700 rpm. A quick throttle up from 1000 psi to 2000 psi, the oil pressure drops to zero and the low oil alarm sounds. New oil, filter and level is correct! No noisy lifters and engine runs smoothly. Should I direct my attention to the oil sending unit? Since it's a one way in, could it be clogged with that thick sticky mess? Can you tell me where on the port engine the sending unit is located? 2004 Mercruiser 6.2L MIE Horizon
     
  2. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    PA
    Various
    Various
    You have a sender and a sensor - both are located by the "stock" oil filter mounting location... aft, port side. Follow your remote oil filter lines and you will find them. The sender controls your gauge, the sensor controls the alarm.
     
    Mac-Daddy-Minnesota likes this.
  3. Calmseas

    Calmseas New Member

    2
    Aug 11, 2018
    04 Searay Sundancer
    Mercruiser 6.2 mine horizon
    Help! Changed the oil pressure sending unit with an OEM one. Changed oil ( 25/40) and filter again. Oil level correct on the dip stick and the stick is correct in the tube. Engine has 600 hrs and ran perfectly before elbow failure. No lifter or bearing noise before or after.
    My next options are, try a mechanical oil pressure guage to eliminate an oil pump problem.
    Jump the port sensor to the starboard sensor to eliminate a faulty oil pressure guage. Am I going in the right direction?? Could the heat exchanger be clogged. Oil cooler or trans cooler??
     
  4. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Your going in the right direction. Forget the exchanger and the coolers
     
  5. Thornton69

    Thornton69 Active Member

    307
    Sep 15, 2014
    Northern BC
    1980 245 SDC
    1984 18' Valco sled
    5.7 260 Merc/ Bravo 2
    Evanrude 115/80 jet
    Confirm oil pressure with a mechanical gauge. No top end noise is promising. If you had ran the engine fore any period of time with water in oil, then it is possible the oil pump has been compromised. Almost sounds like it could be a cavitation issue with the pump.
     
  6. Capt.G

    Capt.G Member

    40
    Apr 14, 2018
    2005 Sundancer 300
    5.0 mercs bravo 3
    With a mechanical gauge still fluctuate?
    Sounds like pressure spring in oil pump or relief valve. Try taking the distributor out and get a drill with a oil pump rod and turn it in reverse direction and then forward to see if that loosens and thing that might be stuck. I would try that first before taking out the motor to change pump
     
  7. Shane Pikor

    Shane Pikor New Member

    1
    Sep 21, 2018
    2003 280 Sundancer, Raymarine 215 vhf
    5.0 Mercruisers w/bravo III drives
    Having trouble finding the oil pressure sender unit on my 5.0 MPI anyone have a good description of where i can find it
     
  8. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    PA
    Various
    Various
    See the second post in this thread.
     
    Jbielec likes this.

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