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  1. #1

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    I need some help/advise leakdown test

    I have been performing all the preventative maintenance and testing that I can find either in the book or on G/H up until today it has been fairly smooth. The ski is a 95 SLT 750
    Today I performed a leakdown test and the results are as follows.

    #'s vacuum____ elapsed time
    9_____________ 0 sec
    8____________ 32 sec
    7_______ 1 min 05 sec
    6_______ 1 min 44 sec
    5_______ 2 min 34 sec
    4_______ 3 min 36 sec
    3_______ 5 min 11 sec
    2_______ 9 min 05 sec

    I squirted soapy water around gaskets and seals noticed nothing.
    I checked the gauge and line to the block and the hose barb on the intake that was for the auto cock.
    Plugged off the coolant line to the exhaust manifold.
    plugged off the coolant line to the coolant rail.
    Smeared grease around the rear seal.
    Checked all of the manifold bolts intake and exhaust, head bolts, cylinder bolts, oil pump bolts.
    Checked again and again after each item and same results.
    The ski starts easy, idles fine and runs good.
    Any and all opinions/advise is welcome
    Thanks


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Soapy water doesn't tell you anything unless the crank case is pressurized, not under vacuum

    To see the bubbles, there must be positive air pressure inside the engine.

  3. #3

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    That definitely makes sense to me. But the thread I read said nothing about pressurizing the block. I was thinking that the whole time but didn't want to do any damage to anything.
    How many pounds of pressure do you think the racket balls that I used to plug the intake and exhaust will hold?
    Only one way to find out huh. Need to get the camera out, I'll end up catching a greasy racket ball in the face.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    You only need a few PSI (under 10 PSI).

    Wear eye protection

  5. #5
    2000 Polaris Pro 1200 rdizz81's Avatar
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    Quote Originally Posted by K447 View Post
    Wear eye protection

    Good Advise...

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    The raquette balls will hold as much as you need, but you will want to secure them with something because they will pop out after psi is applied.

    Raquette ball in exh manifold = duct tape in place

    Cut pieces of racquette ball in intake manifold = put carbs back in place and finger tight nuts.

    Don't use more than 10 psi like K447 said, that's plenty enough.

  7. #7

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    Okay, found 2 leaks and looked for others but nothing.
    Both leaks were on the intake side of the crankcase one at each end. The one at the mag end was definitely the most significant. Not that it was making a hissing noise or seemed to be a lot but it did blow some bubbles ping pong ball size. The leak at the pto end was very small barely blew tiny bubbles about the size of carbon rising in a glass of pop. This could all be due to the contact surface of the soapy water in relationship to the leak.
    How detrimental is this? I know that I would rather not have these leaks but are they bad enough to justify pulling the motor and fixing. How much pressure positive and or negative is generated when the motor is running? I know this isnít an ideal solution but is there a sealant that could be applied externally to these areas?
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  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Ugh.... It's leaking at the seam????

    The cases should be resealed.

    You're this far into now, might as well do it right, rather than be stranded during peak season.

    You don't even need to pull the top end off.

    Remove the engine coupler

    Remove the stator cover, stator, and flywheel

    Flip the engine on it's top (cyl heads).

    Remove the engine plate.

    Unbolt the crank case and remove the bottom half.

    CAREFULLY clean the old silicone from the case halves. Taking care to not get debris all over the crank and pistons.

    Install new crank seals and reaseal the case.

    Can be done in 2 hours, and you only need to buy a new set of seals and a tube of silicone 1211.

    Much better than damaging a piston and having to do it all later if you ask me.

  9. #9

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    Never had a jet ski motor out before. I wasn't sure weather or not I could just remove the bottom half of the crank case or if I would end up having to tear completely down so that is GD news.
    A little about me.
    I've built a 8N ford tractor engine and several car engines, one was so awesome that it was stolen and all the cops found was the body. No motor, no trany, no rear end. I've also wrenched on my boats, more times than I've cared for. Grew up on a farm so I've worked on junk as long as I can remember.
    But wrenching on the jet ski's is rather new to me.
    I currently have three boats and added a fourth jet ski this past Saturday.
    Got a guy that wants to trade me his Sea-Doo, Yamaha and double trailer for a little rail buggy I have. My neighbors will flip, they already ask when are the animals going to start lining up.
    I have a hoist and I believe I have most of the hand tools needed. Just need to get that first one out of the way.

    Question: Will the engine come out with both manifolds attached? Also the gasket at the exhaust pipe looks fine reuse or not?

    Maybe a little unconventional and definitely thinking outside the box.

  10. #10
    bowsniper's Avatar
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    I have the exact same ski as you. undew the engine mounts, the front left of engine is a bracket that connects the pipe to the engine with that bracket, that has to come off too. then disconnect the negative off the englne plate, dissconnect battery, the big pipe needs to be taken off . Undue the big bolts up top on the pipe and the lower one in the back, then dissconnect the water hose on the pipe, theres 1 small one in the back and 1 big one that goes to the front from underneath the engine plate. take the pump off the back of the ski so you can get the driveshaft to pull back, loosen the couple bearing and the shroud around the driveshaft get that out of the way, then dissconnect the fuel lines and the oil injection lines on the side of the motor. when taking off the exhaust manifold, your going to have to slide the big pipe back and forth to get at all the manifold bolts. Then take off the water hose by the thermostat housing. then any electrical i missed. I believe on mine , The stator wires passed thru something and I cut all the wires to replace a bad cdi that burned up. I remember them going thru something..maybe the lower case? I dont remmeber.. I thought ..what a pain in the butt that is.. I routed them a little different after I re-wired them.

    then anything else I missed.l tip the engine a little to aid in clearence and your good too go. watch out for the stator wires coming from under the engine, dont pull on them to hard, just remember they are still attached to the stator!

    Good luck! It goes in easy. reverse the procedurere-use the gasket if its ok looking or add some copper spray to them for better sealing. its high temp stuff by permatex.

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