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Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
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I have a 2004 Yamaha fx cruiser wave runner. It was stored

Customer Question

I have a 2004 Yamaha fx cruiser wave runner. It was stored on a lift with the drain plugs open to drain the hull. Unfortunately, a rainstorm hit and raised the level of the lake to the point it floated the jet ski off the lift. The jet ski did not sink but water reached almost to the top of the battery. When I tried to start it after draining the hull, the engine would not roll. It turned out the cylinders filled with oil and locked the engine up. I removed all 4 plugs and when I attempted to roll the engine, it shot oil up to the ceiling in my garage. Pretty good compression I'd say. I plan to clean the plugs and attempt to restart the engine. What could have caused the cylinders to fill with oil? Will it do it again?
Submitted: 2 years ago.
Category: Boat
Expert:  Joe replied 2 years ago.
Thank you for allowing me to assist you, my name is ***** ***** I will be happy to assist you with your concern today.
Generally this is oil sitting on water, water sits at bottom and oil floats, this means that water entered the cylinders usually via the air intake and any oil combines and thus what you saw come out, or that and the oil once in settles past the rings and goes into the crankcase, as the oil level rises due to water being added the oil floats and makes it's way up the cylinders.
At min what you need to do is drain and change the oil and filter, if water comes out you need to preform water removal process and then change the oil and filter a 2nd time as well. All water needs to be removed from the crankcase or it will cause rust, rust can form in as little as mins/hours on these bare metal internal components, in days/week you can have rusted parts preventing the engine from turning over.
Disable fuel and spark/ignition system and change oil and filter, removing spark plugs and cranking to remove water from cylinders then re-enable fuel and spark and also preforming water removal from engine, run and change oil and filter again.
Thank you!
- Joe
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Customer: replied 2 years ago.
I don't think that was the problem. I believe the wave runner I have has a dry sump. I don't believe oil sits in the crankcase. It sits in a tank mounted even with the valve cover and at the rear of the engine. What came out of the engine was pure oil. The tank was doubt to the add level mark. I'm not sure how much that is but I'm sure it's at least a quart. Is there anything else that would have caused this?
Expert:  Joe replied 2 years ago.
Could have been related to the angle at some point of the hull. It's honestly hard to say without it continuing the problem, if it were to do it again after you cleaned out and refilled then there would be further testing, otherwise it's sort of like trying to find an intermittent problem that is not currently creating the problem per say.
At that point drain out the cylinders and clean them out with a little carb cleaner cranking over to spray it out (rag over the spark plug holes), install new plugs and re-engage fuel and ignition system, should be good to go again.
Customer: replied 2 years ago.
Is there any gasket or seal that could have leaked oil into the engine? When the ski was I the water the stern was low and the bow high due to the water collecting at the back end of the boat. I'm certain the water level never rose to the point where it could enter via the intake.
Customer: replied 2 years ago.
Is there anything else that cold cause oil to accumulate in the cylinder with the engine off? The oil that locked up the engine was clean motor oil-no evidence of water in it or the cylinders. What could have cased this? I'm worried that a restart could lock up the engine and possibly bend something. I know it's not likely and the engine would smoke like crazy if it started burning oil. Just the same, I'd like to at least have a clue as to how that oil got in there and locked up the engine.
Expert:  Joe replied 2 years ago.
By the way, I forgot to mention that the crankcase does have oil in it. The reservoir is just that, when you preform oil changes you cannot get all the oil out as you cannot get all the way to the pan, this is also why there is an oil filter on the engine as oil is in it. It could be that the pwc rolled possibly and thus the oil in the cylinders. Start by changing the oil and filter and make sure there is no water in the crankcase which you can also see by once starting the engine if the oil looks like a milkshake and foamy.
Also check air intake system for oil.
Customer: replied 2 years ago.
Sorry Joe, I'm not trying to be difficult, but the PWC did not ever roll. I have the air cleaner off and can see clearly into the air intakes. There is no evidence of water there. There is no milky oil that was sprayed out of the cylinders or in the reservoir. I'm looking for a better answer than I've gotten so far. COuld the reservoir have been pressurized and forced oil into the engine after it was turned off? Maybe a pressure relief valve that sticks.
Expert:  Joe replied 2 years ago.
The oil reservoir just holds more oil than the crankcase, there is still oil in the engine crankcase. It's possible like I first stated that the pwc suffered being at a certain angle which allowed the oil into the cylinders, be it rolling completely over and back up again or just at an extreme angle. Again, as I explained which I do understand given the circumstance is hard to understand, the best idea right now is to change the oil, flush out the cylinders and get her running again. Then see if it happens again, if so then you can see where during that time or know that it was due to possibly an angle the hull was at.
Customer: replied 2 years ago.
If the oil flowed into the cylinder if the hull was at a bad angle, why didn't it flow back out when the hull was at the correct angle. I don't believe the piston rings seal that tightly that they would prevent oil flow.
Customer: replied 2 years ago.
I will dry the plugs out, dry the engine out, restart and see of the problem recurs. I was hoping an expert could tell me how it got in there in the first place.
Expert:  Joe replied 2 years ago.
Good morning,
To your first reply, that is the exact same answer in either direction you ask, what I mean is that no matter how the oil got in there it can sit on top of the pistons.
I explained various ways it could have got into the cylinders.