Thread: Low Oil Warning

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  1. #1
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    Low Oil Warning

    Put in at a local lake yesterday, and upon launching, I was moving my boat to the curtsey dock. About the time I reached the dock, and alarm went off, Vessel View showed it was a low oil warning. I checked the tank in the bilge area and it was low, but still about 1/3 full, ( I know, I know I shouldn't have let it get that low). Since I didn't have any oil in the truck, i went ahead and loaded back up and headed home. At home I filled the reservoir, put muffs on the motor, and cranked it up and the low oil warning started blaring again. I removed the cowling, and noticed that the engine connected oil tank was about 3/4 full. I researched and saw a video which said to bleed the system by opening the small oil tank screw tab on top and running the engine, the tank would refill itself. So I tried bleeding the system, and let the engine run for approximately 5 minutes and no oil moved into the engine tank and there was also no drop in the level of oil in the tank. The engine is a 2018 Mercury Pro XS 200.

    First any ideas of what may be causing the issue. And also where do I start trying to find the problem and fix the issue, or would I be better off taking it to a mechanic to fix the issue.


    Serial number: 2B529269

    I'm sure there's suppose to be another hose connected here, but I've had this boat since 2019 and it has always been like this, and never had any problems until now.
    Oil Cap.jpegI
    Last edited by Fishahaulic; 03-25-2023 at 08:02 PM. Reason: Added Serial Number
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  2. Member
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    #2
    You will be asked for your serial number but I can give you some idea where to start. There is a poppet valve on the side of your engine block that uses pressurizes your big tank and pushes oil up to the engine tank. Make absolutely sure that your caps on the big tank are tight. If they are leaking there will be no pressurization and no oil will be pushed to the small engine tank. If you run the engine and crack open the big tank cap and feel pressure then check the screen on the bottom of the oil pickup tube on the big tank. Most likely it will be the poppet valve on the side of the block that will be the issue. Check everything else first.
    Old age and treachery will overcome youth and skill

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    #3
    Yes, please provide us with a serial number. Most of the experts on here will not answer the question until you provide your serial number. There could be many reasons why you're not getting oil to the engine tank:

    -faulty crank case check valve
    -kink or damaged oil and air line hoses
    -severely clogged oil filter
    -oil tank leaking - cap not on all the way
    -damaged o-ring or pick up tube


    You can definitely fix this yourself. I wouldn't waste my money going to a mechanic unless 1) He's the best of the best 2) You genuinely do not have the time to do it yourself.

    Good luck, keep us posted.

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    #4
    Could be above or engine oil level sensor
    Ron Fears
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  5. Member lpugh's Avatar
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    #5
    Quote Originally Posted by Fishahaulic View Post
    Put in at a local lake yesterday, and upon launching, I was moving my boat to the curtsey dock. About the time I reached the dock, and alarm went off, Vessel View showed it was a low oil warning. I checked the tank in the bilge area and it was low, but still about 1/3 full, ( I know, I know I shouldn't have let it get that low). Since I didn't have any oil in the truck, i went ahead and loaded back up and headed home. At home I filled the reservoir, put muffs on the motor, and cranked it up and the low oil warning started blaring again. I removed the cowling, and noticed that the engine connected oil tank was about 3/4 full. I researched and saw a video which said to bleed the system by opening the small oil tank screw tab on top and running the engine, the tank would refill itself. So I tried bleeding the system, and let the engine run for approximately 5 minutes and no oil moved into the engine tank and there was also no drop in the level of oil in the tank. The engine is a 2018 Mercury Pro XS 200.

    First any ideas of what may be causing the issue. And also where do I start trying to find the problem and fix the issue, or would I be better off taking it to a mechanic to fix the issue.


    Serial number: 2B529269

    I'm sure there's suppose to be another hose connected here, but I've had this boat since 2019 and it has always been like this, and never had any problems until now.
    Oil Cap.jpegI
    motor mounted tank will never fill with that hose off as it provides the crankcase pressure to operate the system. follow the blue striped hose and you find the black one paired to it. Reattach and retest.
    1/3 of a tank in the bilge reservoir is ok for on trip out unless you are covering 50 miles or more.
    Use radius head zip ties only.
    Thank You Leon Pugh

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    #6
    Blue stripe is pressure isn’t it? If that hose has been off, should be one heck of a mess and also engine is in danger
    Ron Fears
    Stroker/300XS
    1E003823

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    #7
    Quote Originally Posted by lpugh View Post
    motor mounted tank will never fill with that hose off as it provides the crankcase pressure to operate the system. follow the blue striped hose and you find the black one paired to it. Reattach and retest.
    1/3 of a tank in the bilge reservoir is ok for on trip out unless you are covering 50 miles or more.
    Use radius head zip ties only.


    That hose is connected to a port connected to the oil fill hose, and there is no cable tie holding it in place, as shown in the attached pic. When I disconnect this hose from the fill hose, and shine a light into is, I can see the light just under the oil fill cap. I'm pretty sure if I disconnect this hose the oil take will not pressurize. Also I've cut all cable ties holding hoses and wires together and there are no hoses not already connected to something. I am truly confused here.
    Connected Hose.jpg
    Last edited by Fishahaulic; 03-26-2023 at 09:00 AM.
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  8. Member lpugh's Avatar
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    #8
    follow that blue striped hose, the black hose is married to it, the black goes to a check valve in crankcase to #6 cylinder, starboard side below the starter motor. You will need to pull the lower cowls off to gain access.
    Thank You Leon Pugh

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    #9
    Your set up is using pressure to the fill cap. In this case you need to put a cap on the boat tank exposed fitting.
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    #10
    Quote Originally Posted by bass.man65 View Post
    Your set up is using pressure to the fill cap. In this case you need to put a cap on the boat tank exposed fitting.
    Thank you. That's what I was thinking also. What kind of cap and where would I get it from?
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  11. Member lpugh's Avatar
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    #11
    Quote Originally Posted by bass.man65 View Post
    Your set up is using pressure to the fill cap. In this case you need to put a cap on the boat tank exposed fitting.
    No cap, the pressure connects to that fitting, no line = no pressure unless a remote fill has been installed and the has been relocated to filler neck, got to find that hose first and formost
    Last edited by lpugh; 03-27-2023 at 04:35 PM.
    Thank You Leon Pugh

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    #12
    Quote Originally Posted by lpugh View Post
    No cap, the pressure connects to that fitting, no line = no pressure unless a remote fill has been installed and the has been relocated to filler neck, got to find that hose first and formost
    I've found the hose. The hose which is married to the hose with the blue stripe is connected to a port on the oil fill tube. Its also the same hose that is connected to the check valve in the crankcase. Why it's connected to a port on the oil fill tube, I'm not sure. I can easily move it back to the oil cap beside the blue line hose, but I'm still left with a open port at the top of the oil fill tube. Like I said in the original post, it's been like this since I purchased the boat in 2019. Never had a problem with it until this past Friday. Other than changing the lower unit oil, no work has been done by me or anyone else.
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    #13
    So it sounds like you lost the cap (plug) on the oil fill cap. If that is open to the tank then all your pressurization will just go right out that port. Look in the bilge for a rubber cap or some other plugging device. It might have not been clamped properly and popped off. Edit to add: It really doesn't matter where the tank gets pressurized but it cannot have a leak anywhere.
    Old age and treachery will overcome youth and skill

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    #14
    I just finished doing a few test, the results were both good and bad. I started the boat and had my wife plug the open port on the oil reservoir, and left the hose on the port at the oil fill hose. I then went though the steps to bleed the oil tank attached to the engine. Nothing happened. No oil was fed to the engine mounted oil tank. I then switched them, with the hose attached to the port on the oil fill hose while she used her finger to plug the port on the oil fill hose. Immediately the engine oil tank filled. But, there's always a but, it created a severe oil leak, well not really a leak, at the bottom of the oil fill hose. The leak was really a fine straight line spray directly into my wife's face. She backed away before I could turn the engine off and in doing so took her finger off the oil hose port, and when she did, the spraying oil leak got worse, and sprayed completely out of the bilge area, across the back of the boat and over the side rail and onto the ground, so that was obviously a large amount of pressure put into the reservoir. I don't know yet if the hose clamp was tight enough, yet. Still haven't finished the clean up, and that has to wait till tomorrow. How much pressure is suppose to be put into the reservoir?
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  15. Member lpugh's Avatar
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    #15
    put the hose where it was and use a radius head zip tie only to clamp it on. leave the hose on the fill tube and put a cap on the tank fitting, zip tie all connections, Due not substitute regular zip ties for this as it will lead to more problems, motor will have to run 10 minutes to start filling the upper tank if everything else is good.
    about 4 psi
    Thank You Leon Pugh

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    #16
    Quote Originally Posted by lpugh View Post
    put the hose where it was and use a radius head zip tie only to clamp it on. leave the hose on the fill tube and put a cap on the tank fitting, zip tie all connections, Due not substitute regular zip ties for this as it will lead to more problems, motor will have to run 10 minutes to start filling the upper tank if everything else is good.
    about 4 psi
    Thanks, Radius head zip ties have been ordered and should be here tomorrow. After the clean up is finished I'll try to find a cap that fits the tank fitting. Again, thanks
    USAF Retired 1981-2004
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