1997 Merc 75 HP - Oil Consumption High

[johnjsa]

My 1997 Mercury 75 hp on my boat seems to consume way too much oil & also at times idles rough maybe because of this. Is there an adjustment or anything on these motors?

 

[ufm82]

Re: 1997 Merc 75 HP - Oil Consumption High

Is this a 4 stroke? If a 2 stroke I'll assume it's an auto-mix engine? How much does it use? Do you see excessive smoke? (My 150 smokes at start up only for the most part.) How much are you using?
If it is mixing heavy yes, it could cause an idle issue, especially if it is fouling plugs or interfering with good combustion.

Need more info-

 

[Chris1956]

Re: 1997 Merc 75 HP - Oil Consumption High

I presume it is 2 cycle with oil injection? If so, look for air leaks into the gasoline side of the fuel system. Check all fuel filter connections, primer bulb and tank connection and the main strainer under the airbox, if you have one.

 

[Silvertip]

Re: 1997 Merc 75 HP - Oil Consumption High

Under normal operating conditions, it should consume the same amount of oil as if it was burning pre-mix at a ration of 50:1 or one pint in six gallons. To check this, place a mark on the oil tank and then fill the fuel tank. Now pick a time when you can make a long (one hour or more) run at about 3/4 throttle. The run doesn't have to be all at one time but if run in segments, log the time. With a moderate load, on a 17 foot boat, your engine will burn somewhere between 5 and 6 gallons of fuel per hour. At the end of that hour, check the amount of oil it takes to bring the level back up to the line you made. If it took a pint or thereabouts, oil consumption is normal.

 

[jeffersondodson561]

Re: 1997 Merc 75 HP - Oil Consumption High

If the link rod becomes broken or unattached it will retract to the full WOT position of 50:1 ratio. As for the syncronization refer to attached:

 

[Chris1956]

Re: 1997 Merc 75 HP - Oil Consumption High

John, I had a senior moment. My fix only works for Johnnyrudes. The Mercs have a different oil injection system.