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  1. #1
    Join Date
    Oct 2007
    Location
    Myrtle Beach, SC, USA
    Posts
    4

    Default Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    I purchased a new boat and drove it about 20 hours. I stopped to get fuel and could not get the engine to start back up. It was hard to turn over (as if starter was failed or low battery). I checked the oil and found it was WAY too full and thinned. Drained about 4 gallons of oil/gas out of engine.
    I have pulled plugs. No water in cylinders or drained oil. Engine will not turn over with plugs in, but will turn over with plugs out. I waited 24 hours, same result. I have cranked engine over for about 3-4 seconds with plugs out. No globs of oil expelled. Replaced plugs same result, slow crank, no start. I have added new oil to "low" end of dipstick range. I have replaced starter with new & battery with new, fully charged and checked all power leads & connections.
    What could the problem be? Hydraulic lifters? Valves? Any suggestions on tests to run? I'm thinking a compression check on compression & exhaust stroke may offer insight. But, I don't know what these numbers should be.
    2nd engine seems to be developing similar issues but will still start. I intend to replace/rebuild both carburetors (Quadrajets).
    Engines are Crusader Model 350 (454s), SN#51764 & 51767, 1985 Marinette 39' Double Cabin.

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,760

    Default Re: Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    OK - it's a "new to you" boat thats really 30+ years old.....

    If the engines are original, how many hours are on them?

    How did you check "all power leads"?

    Not sure what you are getting at with the compression test thought....the revised basic GM procedure compression check is now done cold, grounded/disabled ignition and throttle wide open....100 PSI minimum and min value within 30% of max value (based on memory).

    Running 20 hours with gasoline laden oil surely didn't due the bearing surfaces any good. I'd say an oil analysis would be beneficial but with fresh oil won't tell you too much - any chance the old oil filters are still around?

    how's the oil level condition on the functioning engine? finally do you have any maintenance records?

  3. #3
    Join Date
    Mar 2015
    Location
    Deale, Md.
    Posts
    19

    Default Re: Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    I'd be very concerned and careful if I had gallons of gas in my oil pan.
    Check your fuel pump.

  4. #4
    Join Date
    Oct 2007
    Location
    Myrtle Beach, SC, USA
    Posts
    4

    Default Re: Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    Quote Originally Posted by old bird View Post
    I'd be very concerned and careful if I had gallons of gas in my oil pan.
    Check your fuel pump.
    I don't understand how a fuel pump would keep an engine from crankimg over.

    On the other front, I don't have any idea how many hours, and have no maintenance records. Power leads inspected visually for corrosion on new starter install.
    I am far from a mechanic, but am wondering if hydraulic lifters are not opening valves on exhaust stroke.
    How would engine hours affect tha ability of an engine to turn over?

  5. #5
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,760

    Default Re: Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    If the fuel pump diaphragm fails, excess fuel is supposed to be routed to the carb via the sight tube. the engine will run very rough and the exhaust will be rich. if the pump is not designated for marine use (an auto pump) and the diaphragm fails, the leaking fuel usually gets dumped into the crankcase....so, a leaking pump wont prohibit cranking but could be a contributor to the cause of the cranking issue.....

    No maintenance records mean you don't know what has or hasn't been done....Visually inspecting high current carrying wires is really meaningless....a voltage drop measurement is really needed.

    Your lifter theory means the exhaust lobes on the cam are wiped....if they are and it occurred recently, then the intake lobes should be in the same boat - and I'd suspect the diluted oil being a contributor.

    The engine hours give you a decent gauge of where the engine is in its finite lifespan.

  6. #6
    Join Date
    Oct 2007
    Location
    Myrtle Beach, SC, USA
    Posts
    4

    Default Re: Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    I'm back where I have a computer to respond. After your first post makomark it occurred to me exactly what you said in your second post was very true. Visual inspection not a reliable study. I did run checks on the voltage and traced low voltage from the Perko main battery switch. While I have not resolved the issue entirely (I may have to replace all old switches), I have found that bypassing the whole "christmas tree" by running from battery to starter with 4' of wire fixes the problem. Thanks for the input. Additionally, I appreciate the input on dumping of fuel into crankcase if the fuel pump is not marine rated. That is stellar information I did not have. I will replace the fuel pump. I have found A LOT of non-marine-compliant handywork on this vessel.
    Last edited by bryandavis; 07-24-2017 at 09:42 PM.

  7. #7
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,760

    Default Re: Gas in oil, engine hard to turn over with spark plugs in, turns over with plugs out

    glad you understand what's going on.....FWIW, insist on HIGH QUALITY electrical products and WORKMANSHIP. for wiring, use tinned, stranded wire with a recognized insulation and properly executed terminations (more than one way to do these).

    The "marine rated" labels on all the potential spark producing electrical items are mandated for many reasons - the biggest one is your safety. Sadly, I know of more than one instance where liability for a mishap was due to using a non-marine-rated part.....and insurance usually wont cover these situations....

    Finally, assuming the fuel pump is not rated, and you replace it with a marine rated one, make you you complete the installation correctly....

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