High oil consumption on one engine

Discussion in 'General Maintenance/Repair Questions' started by YeOldeStonecat, Aug 26, 2019.

  1. cfd95

    cfd95 Member

    Nov 5, 2013
    Northport Long Island
    2002 310 Sundancer
    350 Horizons
    V Drives
    I would check the transmission coolers also.
    When they fail you will see an oil sheen in the water.
  2. DWABoat

    DWABoat Active Member

    Aug 13, 2019
    S Louisiana
    2001 280 Sundancer
    1989 220CC Cuddy Cabin
    Twin 4.3 w/Alpha Ones
    5.7 Mercruiser Alpha One
    Wow! $10K will buy a lot a oil!
    My first two cars burned and leaked oil but ran for many years. As long as it cranks, runs reliably, and your not polluting a sheen behind you, run it!!!
    That’s just me though.
  3. douglee25

    douglee25 Well-Known Member

    Jan 13, 2008
    Dallas, TX
    Cruisers 3575
    Twin 7.4l
    There is a fuel/oil treatment by Schaeffers called Neutra Fuel Stabilizer 131. You can run this in your fuel but also in your oil to help break down carbon deposits. IF if it's a stuck ring or valve, this could help free it up. Read online. The stuff works.
  4. BillK2632

    BillK2632 Well-Known Member GOLD Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    You didn't say what the actual oil usage was after you replaced the PCV valves. Even though one cylinder is lower than the others, it is still within spec (within 70% of the others). You need to do another compression test with a leakdown test to determine where that cylinder is loosing compression. Reworking the heads is a lot cheaper than a long block. So it's using some oil - the engines are 23yrs old - nothing at all wrong with running it while you figure this out. And personally I would think twice before I put any significant $$ in a 23yr old boat - if you like the boat and intend to keep it then do it, but don't think you will ever get the $$ out of. For the $10k you mechanic is talking, you could buy a complete reman.
  5. YeOldeStonecat

    YeOldeStonecat Active Member

    Jun 10, 2018
    Waterford, CT
    '97 300 DA "Me-Shell"
    Twin 5.7 V-Drive
    Same....replacement of PCVs didn't impact the oil consumption.

    Realistic about not getting the money back on sale of the boat. It's like spending 85 grand putting in an all new kitchen or roof on your house before selling it...doesn't mean the price of the house went up 85k. But it can help sell the house if the whole price is right.

    While we dream of upgrading to a 37-40....that's not for a couple of years..so we'll have this boat at least another 2-3.
    Last edited: Dec 10, 2019
  6. BillK2632

    BillK2632 Well-Known Member GOLD Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    So my next step would be to find out what is really wrong - could be you just need the heads reworked, if so that is not too bad. If you are getting into the bottom of the motor, I would really look at a complete reman like a Michigan Motorz. By the way, the older 300's with v-drives are nice boats, worth investing the $$ in to keep in my opinion.
  7. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    5.7's are plentifull and cheap. Buy a long block for around 2k and bolt all your stuff to it.
  8. bahamabreisus

    bahamabreisus Well-Known Member

    Oct 25, 2007
    Hampstead NC
    500 dancer, previous 420,390,300 dancers
    detriot 8v92
    Lucas makes some really good additives. I have seen them work miracles in many car engines, transmission and steering. Lucas used to be for the big truck industry years ago.

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