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150 Mariner - burning too much oil

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  • 150 Mariner - burning too much oil

    I have a 1996 150 Mariner (2.0) that is burning too much oil and having trouble cold starting. I think I may have caused it myself by putting a new fuel line on in reverse (real smart huh!). I primed the bulb several times which ended up sucking TCW3 through the pump and 2psi check valve. Then realized my stupid move and switched the hose around. To make matters worse, one of my equally absent minded fishing partners had knocked the arm off of the oil pump which meant that the outboard was being run with the oil pump maxed out for the next couple of fishing trips.Since then, my engine has failed to cold start on several trips. The plugs are always fouled with wet oil when I have trouble cold starting. I can get it running by cleaning the plugs or using ether (I know, bad move) but find that it is pushing plenty of smoke and plenty of unburned oil is hitting the water.Do any of you think that I've damaged the oil pump or the 2psi valve or both??? Or is the "wrong oil pump end plate" problem that ODDD1 has mentioned in the past a contributing factor?Please help?!

  • #2
    Re: 150 Mariner - burning too much oil

    Pawpaw1, thank ODDD1 I am checking out oil pump end plate problem and the 2 psi. check valve in the spring. Boat in storage now. Go to your local Mercury Dealer only and have them run your serial number through Mercury Marine. That is what I did and I might have thje wrong oil end plate. But still open for other ideas. Have a Merry Chritmas


    • #3
      Re: 150 Mariner - burning too much oil

      Ok, both you guys...the end plate prob was SPECIFIC to the 40 hp 4 cyl...never a v-6 prob....2 check valves you need to check, the oil output check valve [2 psi], of which i have replaced alot of, or the check valve that pressurises the remote oil tank with crankcase air...the air pressure valve is easy to check, after several minutes with the engine running, turn motor off and WAIT 4/5 minutes..unscrew the remote oil tank cap and listen for escaping air pressure...any air pressure found doing this means the valve is bad....if this one is OK, you can assume the oil output valve is bad and replace.......


      • #4
        Re: 150 Mariner - burning too much oil

        ODDD1: One more question on the 2 psi oil output check valve. Clymer's said that this valve is in place to prevent gasoine from being forced into the oil line. Is this valve also in place to limit the amount of oil that can enter the fuel line when the motor sits up for a few days?I disconnected my fuel line this weekend and found that 100% oil was in the line. This is obviously why I can't cold start. Also, I thought the check vavle that uses crankcase air to pressurize the remote tank was one way. Should the pressure go down when the motor is not running? I can't remember my remote tank ever not being pressurized in the six years that I've owned the boat. If I remove the cap a month after the boat has been run, it still has plenty of pressure. I have noticed that the remote tank does look kind of bloated these days. Have I had a problem all this time without knowing it?Thanks


        • #5
          Re: 150 Mariner - burning too much oil

          0pawpaw, that output check valve is in the line for another reason besides just separating the gas and oil...those mikuni oil pumps are calibrated to mix correctly against a 2 psi head pressure...if it is not there, they will pump too much oil....as far as your air press valve is concerned, it is bad...it should bleed off pressure when motor is off....in the old days [late 80's] merc didn't put the pressure bleed off on the check valves, and they changed them precisely for this problem.......


          • #6
            Re: 150 Mariner - burning too much oil

            ODDD1: Thanks for the info. Hopefully I'll get this worked out. One more ruined fishing trip and I'm going to pitch the whole oil injection system.