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  1. #1
    Resident "Noob" Sabu1984's Avatar
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    What the heck is this noise!??!

    Hey fellas
    Newbie jet ski lover here... Been watching these forums forever learning, but now that i FINALLY bought my first ski, i expect to be a regular on here! Anyyyyyywho, I just bought 96 SLX 780, third owner, mfd shows 70 hours. Got an issue maye you guys can help me diagnose...

    Took it out for the 3rd time this past thursday and it went crazy on me. First 2 times i took it out, ran great, no problems what so ever, now suddenly somethings up. When i was coming back in, when i would hit the throttle, the engine would be quite a bit louder, almost a "metal vibrating" sound if that makes sense. While in the water, it only did it when you gave it some gas. I could still easily get it up to full speed (around 65 give or take) but didnt do it but once, didnt like that noise at all.

    I thought i may have sucked something up, so i took out of the water, and looked underneath and around the impellar and saw not a single thing.

    Got home, hooked up the flush kit, and as soon as it cut the water on, (after letting it idle first), it sounded like it was about to friggin blow up. It had a REALLY rough idle. I messed with it again earlier, and the engine is crazy loud. Starts fine, but idles pretty rough, alot rougher than it did when i first got it. When i cut the water on this time, it almost cut out, but didnt. According the MDF its idling at 2500 rpms, whichs seems high to me. What could have suddenly happend? Im scared to take it out on the water now cause it actually sounds like its going to blow up. I noticed that the cooling channel was VERY hot when i took it out of the lake, not sure if thats normal or not. When i tested it earlier at home, the first cylinder got REALLY hot almost instantly, while the 3rd one was still cool...

    Side note question too.... Ive rode my SLX about 5 hours (before this happend) and ive noticed ive burned hardly any oil at all.... how long will a typical tank of oil last? I figured i would have gone through more than that.....

    Any ideas or HELP would be GREATLY appreicated! =)

    Thanks ALOT!
    Mark


  2. #2
    AWA Member 32DegH2O's Avatar
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    DO NOT start it again...you may be loosing a piston sounds like or you have a bad pump stator...either are familiar issues with this watercraft. First I would try to look down the spark plug hole in each cylinder and see if anything jumps out at you...most likely you'll see a damaged front piston. If everything looks good, do a compression test...what are the results? If low compression in any cylinder, remove the head and see what's up. If everything looks good, then you are probably loosing the crank...should notice scraps on the cylinder walls if this is happening or chips/dents in the cylinder heads. If everything looks good, then dig into the stator. Post any pics of what you find out.

    Edit: Why did it take so long to get to the pump?
    Last edited by 32DegH2O; 09-13-2007 at 02:34 PM.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk. Do a compression test for the rough idle. Does the engine turn freely by hand if you remove the sparkplugs and engine coupler cover? Have you greased the through hull fitting lately? (any water intrusion noticed?) Has the thermostat been removed? If not, remove it. What is "cut the water on?" 2500 RPM idle is normal out of the water. MAG cyl will get hot when running it on the flush kit while the other 2 are cool. (normal because it's the last to get water) Little oil is burned up. just keep topping it off every fill up. Or go with a block off for the injector and go premix.

  4. #4
    Resident "Noob" Sabu1984's Avatar
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    hey there
    Thanks for the replies....
    Im gonna go buy a compression gauge tomorrow and ill post what i find out... Im not too knowledgable about watercraft just yet, but im trying to learn. I looked in the spark plugs holes, and nothing bad jumped out at me, of course then again, not really sure what im looking for. Im the third owner, and im pretty sure the guy before me never did any sort of maintenance on it. I couldnt tell you if anything was ever lubcricated or not. I did grease today the one grease fitting i noticed on what i assume was the drive shaft, any other vital parts that i should check for? Not sure what is meant by the through hull fitting. I changed the spark plugs, and according to the Clymer manual i have, the ones i took out where the wrong ones to begin with. I did take the thermostat and pop off valve off today, made sure they where clean, but i didnt leave the thermostat out. What would taking the thermostat out help do? I does start fine, no problems, just sounds horrible to me. Ill let you know what find about the compression.... any other things to look for? Oh yeah, how can check does if the engine turns over by hand? Sorry if these are some newbie questions... remember, im just learning here.... thanks for your help thus far...
    Mark

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    The through hull seal (my bad I said fitting) is the part you greased that the drive shaft runs through, seals water from entering the hull. If it's not greased it will wear and let water in, I was thinking if it was bone dry it may make a metal vibration noise. The plugs you should be using are the NGK BR8ES. Leaving the thermostat out has no problems unless you ride in real cold water, but if it doesn't open you'll overheat. Turning the engine over by hand with the plugs removed will help tell if your crank bearings or jet pump bearings are failing.

  6. #6
    AWA Member 32DegH2O's Avatar
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    Just a note...the through hull seal (the part that gets greased) also has bearings in it that can go bad and cause a grinding sound...but you would most likely be getting water in the hull if this was the case.

  7. #7
    Quote Originally Posted by JetskiMN View Post
    Just a note...the through hull seal (the part that gets greased) also has bearings in it that can go bad and cause a grinding sound...but you would most likely be getting water in the hull if this was the case.
    i had this happen on a 92sl650. def made a terrible noise, but im guessing this is not your problem, give it a look anyway though

  8. #8
    Resident "Noob" Sabu1984's Avatar
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    i took a few pics, one of the old spark plugs i took out, (which were the BR7ES that i took out and replaced with 8's) and the other circled the fitting i was speaking.... was curious if that what the hull fitting you were speaking off.....
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  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by xlint89 View Post
    The through hull seal (my bad I said fitting) is the part you greased that the drive shaft runs through, seals water from entering the hull. If it's not greased it will wear and let water in, I was thinking if it was bone dry it may make a metal vibration noise. The plugs you should be using are the NGK BR8ES. Leaving the thermostat out has no problems unless you ride in real cold water, but if it doesn't open you'll overheat. Turning the engine over by hand with the plugs removed will help tell if your crank bearings or jet pump bearings are failing.
    Did you read this post?

  10. #10
    Resident "Noob" Sabu1984's Avatar
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    yeah read that post, but im still learning remember, just wanted to make sure that was the same spot you guys where speaking of... There isnt a whole lot of water coming in, actually hardly any, at least that i can tell.... as far as the thermostat thing goes... the lakes around here are anywhere from around 75 to 90 degree when id be riding, so by taking the thermostat out should help with the cooling aspect? Im going out now and taking the plugs out to take see if i can turn the engine over by hand.... couldnt get hold of a compression gauge today.... ill try again tomorrow..... thanks for everyones help thus far, seriously... I GREATLY appreciate it!

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