Oil pressure

zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
I have twin 4.3 mercs.
i had the engines running at the dock yesterday and noticed something weird.
cold start at idle oil shows 40 on port and star Gages.
if I increase the Rpms on the star engine oil jumps to 55 - 60 and stays there never falling to 40. If I keep giving it throttle it does move from 55 to higher reading and then back to 55.
if I shut the engine down and restart it still shows higher then port. Only on cold starts it reads identical 
bad gage or sending unit?
i might check the wires to make sure there are not loose.
all other readings are indebtic all to each other and idle and sync is spot on

Comments

  • LaReaLaRea Member, Moderator Posts: 7,756 mod
    Look for loose ground wires on the gauges.  Have you tried the old Faria "tap the face of the gauge with your finger" trick?  
  • Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Yup. Grounds are #1. 

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
  • zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
    I did lol
    i will start checking 
  • buggyjdavbuggyjdav Member Posts: 134 ✭✭
    I have the exact same issue, same port engine although I have the 5.0 Horizons
  • zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
    edited June 2016
    Ye I will look into it tomorrow or this weekend.
    during original startup Gages read 40 at idle 
    star engine jumps to 55 or 60 at rev but then never really falls. If you restart sometimes it goes back to 40 or reads high.
    could be the wiring or pressure switch or gage lol.
  • 212rowboat212rowboat Member Posts: 2,593 ✭✭✭✭✭
    so..... I'd swap filters... 

    the sensor is just beyond the filter... flow doesn't create pressure, pressure can be a measurement of flow, though.... your filter may be compromised and your pressure off.  it may be bypassing the filter altogether.  
  • zaverin1zaverin1 Member Posts: 1,672 ✭✭✭
    I will check my filter
    i know I have remote filters and I replaced them this year.
    i will check the wire on top and bottom sensors
  • Michael TMichael T Member Posts: 7,227 ✭✭✭✭✭

    If you used mercruiser high efficiency filters they are very well constructed and likely to have similar tolerances. I replaced them a number of times on twin engines with Vessel View systems. Oil pressures were always very similar although they can change a bit between engines and even between engines after an oil and filter change.

    But, IMO wild swings look like wiring (ground always the first culprit to look for) then the oil pressure sender.

    As far as gauges, if you have Faria gauges well.......

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