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  1. #1

    Exclamation Oil at bottom of hull?!

    Hi! After 2 years of boating I recently decided to buy a jet ski. It is a 1995 Polaris sl 750. When I went to pick it up everything appeared ok except there was a layer oil at the bottom throughout the hull. Since the price was right and it sounded ok running, i bought it. A week after I bought it home, I started it and ran it a couple of minutes. Then I cleaned up the oil. The next day I looked into the compartment again and there was a layer of oil again, though not as much nor as widespread. Any ideas?

    P.S. Sorry if the answer is so obvious, but im a complete noob on jet skis (already ordered manual).

  2. #2
    ryandi2's Avatar
    Join Date
    Aug 2009
    conesus ny!
    welcome to the hulk.

    this could be a few things in my opinion, i would first check your oil tank its self to see if there is cracks but i would also check all the oil lines i bet ether one fell off the carb or they are cracked, you should not run your engine untill you figure it out, or you can mix some oil and gas and run it that way to try and find the leak.

    if you dont come up with anything check your engine block its self, but i would go threw the oil lines real good

  3. #3
    I took my '97 1050 out for the first time last weekend. The oil warning was flashing the whole time even though I had a full tank. At the end of the day I pulled the bilge plug to find an alarming amount of oil in the hull.

    Baffled, I first started to figure out what was wrong with the oil level sender. I pulled the oil tank only to find no sender at all and a big gaping hole where the sender should be! Upon further investigation, I traced the wires from the e-box and found the sender stuffed under/behind the fuel tank.

    Lesson: Sometimes the fix is really, really obvious.

    Lesson # 2: Previous owners to skis can do some really, really stupid stuff.

    It took me about 2 hours to wash all the oil out of the hull. I had to leave a couple of absorbent petroleum diapers in the bottom to catch the residual stuff.

  4. #4
    Think about removing the oil pump and going pre-mix. see

    Oil Pump

    Removing the oil pump is do-able but…. Extremely! , Extremely ! ….difficult, as you have to use a combination of mirrors to see. Be aware the Allen head bolts that hold the pump in place are Metric. Drain the tank before you remove the oil lines.

    I first tried to seal the Block-Off Plate using an O-ring, but discovered that just would not work.( Couldn’t get hands in there). I finally used thin gasket material (per call to SBT), (made a gasket) coating all sides with RTV, which sealed OK.

    I also wired in, a 33-35 ohm resistor in the oil indicator line to fool the MFD. ( I don’t know if the engine would start if the oil tank was empty or not since my MFD does not work)

    See post about replacing original fuel pump with a Mikuni 3 outlet one.
    Last edited by dorf; 04-05-2010 at 07:36 AM. Reason: added fuel pump

  5. #5
    Will Learn For Food unenergizer's Avatar
    Join Date
    Mar 2010
    Beaumont, Texas
    Welcome to the HUlK!

    Yes you need to check all your oil lines. When I picked up my SL 750 oil was EVERYWHERE in the hull. I have now concluded that a nipple broke off my carbs and the oil was exiting the broken line.

    You shouldn't run the engine at all until you find the problem. If you wan't you can turn the engine over by lightly pressing start and watch to see where oil might be coming from.

    Being that your ski is as old as mine I would suggest replacing all lines in your ski. I think i read somewhere you need about 20 ft for fuel and about the same for your oil lines. Also remember to replace the screw connectors as they are no longer good (well thats what my CLYMERS shop manual says).

    The Clymers shop manual (1992-1995) covers almost everything you need to know. What the manual doesn't cover you can find here.

    Good Luck,

  6. #6
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Welcome to the Hulk

    Click the link below, and read up on some common things to look for, and pay attention to.

    Cleaning oil out of the hull can take some time, as it can seep out from under the fuel tank and other hard to clean areas.

    One trick I have used is to pour a strong mixture of degreaser and warm water into the hull (several gallons), then take it for a ride on the trailer. The sloshing around helps loosen and disolve the oil and dirt. Let it sit for a while, then go for another short trailer ride to loosen the dirt some more.

    Then tip the trailer nose up high, and rinse the hull out well.

    I would suggest replacing all the oil lines with new. As you do so, you may find a cracked hose or leaking clamp.

    Replace the fuel lines, and filter too.

    The original hoses are now 15 years old, and no longer to be trusted.

    It is worthwhile to visually and physically check everything you can, from one end to the other, on your Polaris PWC.

    Plan to clean and rebuild the carburetors too. It is important that the fuel system all the way from tank to engine intake be 100% good.

  7. #7

    Smile thank you for the replies

    At this point I think it would be best to go premix. I went and looked to see if I could find the leak on any of the hoses coming from the oil tank but didnt see any. The oil tank itself appeared fine as well. I felt around the oil pump and it had a layer of oil on it so I suspect thats were the problems at. I couldnt adequately give it a visual inspection given its location. Anyway the consensous here and on other threads is to go premix on a jet ski this old which is what Im going to go with. Also I plan to rebuild the carbs and replace the stock fuel pump and fuel lines. Once again TY for the replies.

  8. #8
    I keep getting oil collecting in the bottom of the hull. It cant be the oil lines since I went premix and removed the oil pump, oil lines and oil tank. Its not a huge amount oil but its there. I even removed the pulse line to see if anything would drain out but nothing did. So am I looking at an engine block problem as suggested above by ryandi2? Should I pull the engine?

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Where are you seeing this oil? front or back of the ski?

  10. #10
    Quote Originally Posted by xlint89 View Post
    Where are you seeing this oil? front or back of the ski?
    Towards the back of the engine. It pools around the engine plate battery cable mount. Looking in from above the fuel tank, I can see small oil deposits on the engine plate crevices on either sides of the engine itself (under the carbs and under the starter). No oil forward.

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