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Taking care of your on-board oil injection system

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  • Taking care of your on-board oil injection system

    In my latest SML report I shared that I'd had a low oil pressure alert during practice and again on TX day. This is something that has plagued me for almost the entire time I've owned this boat. I'm thrilled to report that big motor is fine - no damage, no issues. I did learn a few valuable lessons from the diagnosis and resolution processes. Sharing those here in the hope it'll help y'all avoid this problem in the future.

    1) First of all, the technician was quick to chastise me for not fishing enough (in jest, of course). I've had this sled for almost 2 years and I just passed the 50-hour mark while on SML this past weekend. Outboards don't like to sit. They like to be run. 2) Most germane to this story, the oil in the reservoir doesn't like to sit. It likes to be cycled thru the motor. When it sits the residual moisture in settles to the bottom and over time forms a sludge. That sludge gets sucked up into the oil lines and the rest of the injection system. Instant loss of oil pressure. That was the case on my sled. Additionally, the oil rez was filled with bulk product when the boys in the shop set it up for delivery. My plans for the new sled didn't include letting it sit for ~7 months while I rehabbed from shoulder surgery. The combination of moisture-rich oil and an extended period of no running likely contributed to my problem. 3) Not all oil 2-stroke oil is created equal. More importantly, not all 2-stroke oil ages or stores equally. Bulk products tend to accumulate moisture over time. If they're not turned (mixed thoroughly) regularly that moisture settles at the bottom of the barrel. When the lads at the marine store fill up your oil jug the pump in that barrel most likely draws from the bottom - where the moisture is. We all love the price break that comes with buying bulk oil. If the store we're buying it from isn't keeping (turning) the bulk oil properly the money we save could be going into a significant engine service or repair. The easy option is to buy off-the-shelf sealed jugs. Even then there's still a chance you'll have some residual moisture. The longer term solution is to let that oil rez get low (but not dangerously low!) before you refill it. That's a simple way of minimizing the potential for sludge build-up.

    My comments on getting to know and trust your on-board gauges and warning tones (plz see my SML report for 27-29 FEB) ring true here. The SmartCraft gauges were telling me early on I had a systemic issue. Had I pressed on with running the big motor after hearing the high temp alert I could've done some serious damage. Yeah, the safeguard is designed to kick in well in advance of engine damage or failure. You can bank on that and take your chances. Or you can err on the side of safety and shut'er down. A new 150 is about $15-20K. A new 250 is ~twice that. The math is pretty simple for me.

    So, ol' Airborne will be back in action this weekend (SoHo).


  • #2
    Originally posted by 31Airborne View Post
    The longer term solution is to let that oil rez get low (but not dangerously low!) before you refill it. That's a simple way of minimizing the potential for sludge build-up.

    An empty tank (fuel or oil) can be more likely to develop condensation when temperature changes causes humidity in the air inside of the tank to condense on the inside of the tank. If the tank is full, there is less air in the tank that contains humidity.

    The best cure is to keep the sled in a heated space (not likely to happen) or fish more so there is less time for moisture to build up from repeated temperature cycles.


    • #3
      What he said.
      2013 Frog Only Tournament Winner
      2010 Tie for VA-Outdoors Angler of the Year
      2009 Caroline County Rotary Club Tournament Winner
      2007 Tuesday Night Classic Champions
      "Many men go fishing all of their lives without knowing that it is not fish they are after."



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