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  1. #1

    Trying to diagnose engine noise

    The engine in my 1200 seems like it has started to vibrate more and I now hear a metallic sound wherever I chop the throttle or unload the pump. It sound like it is coming from the front of the motor but it is very hard to tell. I have been trying to diagnose the problem but have had no luck finding anything. It still ran good last time I was out 6650 RPM and 60+ mph.
    The things I have done so far:
    1. Removed the pump and checked pump bearings (seemed to be good)
    2. Checked compression on all 3 cylinders (130 psi and even)
    3. Checked motor mounts and all seem tight
    4. Removed the head from front cylinder and everything looks good(will do the other two looking at cylinders)
    Does anyone else have any ideas on easy things that I might check before disassembling the motor any more? I am trying to eliminate everything before I just start taking it apart.

    Thanks in advance for the help.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    What model and year is your Polaris?

    Does it make the sound when running on the trailer?

    Does it make the noise when running the engine with the jet pump and drive shaft removed?

    If sound is absent when jet pump is removed;
    Check the splines on both ends of drive shaft and impeller and PTO coupler splines for wear.

    Make sure the rubber bumpers are in place on both ends of drive shaft.

    Check the through-hull bearing for wear or slop. Consider replacing the seals and inspecting the internal bushing in the through-hull assembly while you have the drive shaft out.

    Check for signs of impeller blades touching the wear ring.

    When you re-install the jet pump, be sure to grease the splines before re-assembly. Use Waterproof marine bearing grease.

  3. #3
    bowsniper's Avatar
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    maybe the flywheel nut is loose and the washer is banging around , take the stator cover off and see if the crank nut is tight.. that just happened to my pro and another members ski.. mine was loose and his fell off completly.. is the starter sounding like its engaging the flywheel correctly? worth a try to look.

    wobble the engine and see if its connected to the plate.. sometimes the bolt or bolts fall out of the bottom of the cases.

    or possibly the driveshaft splines are worn or in the coupler. becareful looking at the coupler, it could be sharpened up from the splines being worn. dont run your finger in there to fast or else it could cut you. a few ideas to kick around .

  4. #4
    K447 It is a 2000 Pro 1200
    I can’t get it to make the noise on the trailer. It does vibrate what seems like a lot but maybe that is just normal for a 3 cyl.
    I did run it with the pump off. How much play (side to side) should there be in the drive shaft? It did seem to move around quite a bit. Also should the shaft just pull out?
    The Impeller and wear ring had very little wear with only minor nicks in it.
    Bowsniper
    Is it common for the flywheel nut to come loose? I will check mine in hopes that is all that it is. If that happens does it affect the operation? I did check the mounts and they all appear to be tight.
    Thanks for the info I’ll follow up with the suggestions.

  5. #5

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    if the wheel nut came loose the woodruff position key would be sheared and you would have alot more problems than vibration , it would be out of time and prolly wouldnt run

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by airdog View Post
    ...It is a 2000 Pro 1200
    I can’t get it to make the noise on the trailer. It does vibrate what seems like a lot but maybe that is just normal for a 3 cyl.
    I did run it with the pump off. How much play (side to side) should there be in the drive shaft? It did seem to move around quite a bit. Also should the shaft just pull out?
    The Impeller and wear ring had very little wear with only minor nicks in it....
    Did you run it with the jet pump removed, but the drive shaft still in place? That would not be good.

    When the jet pump is installed, the drive shaft should have virtually zero play, side to side or front to rear.

    The drive shaft simply pulls out the rear. Often it comes out with the jet pump, splines still stuck inside the impeller nose.

    Evey time the jet pump is removed, the drive shaft should be inspected and greased at both ends. Look for wear in the areas on the shaft where the through-hull bearing rides.

    The Poalris 1200 engines do have significant vibration right around 2200RPM, but then it smooths out again above that.

  7. #7
    I did start it with the drive shaft still in place for about a minute, hpoe I didn't hurt anything. It would not pull out easily, I guess I just need to yank harder.
    I pulled the other heads off and they looked good.
    Checked flywheel it was also good. Removed the exhaust(that was a task due to corrosion on everything) I will now try and pull the cylinders and check the crank. Isthere a special tool for the back cylinder nuts?
    It looks like the motor has been torn down before the cylinders appear to be sleeved.

    Is it possible the noise is coming from the starter bendix? Do they go bad? It seems to make a little noise but maybe that is just because I have the flywheel cover off.

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    The Bendix is supposed to be supported by the flywheel cover. It is not designed to be started without the front shaft of the Bendix supported.

    If you can see the Bendix, you can examine it for signs of damage. A small mirror may help. Or stick your digital camera down there

  9. #9
    750sl's Avatar
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    Quote Originally Posted by bowsniper View Post
    maybe the flywheel nut is loose and the washer is banging around , take the stator cover off and see if the crank nut is tight.. that just happened to my pro and another members ski.. mine was loose and his fell off completly.. is the starter sounding like its engaging the flywheel correctly? worth a try to look.

    wobble the engine and see if its connected to the plate.. sometimes the bolt or bolts fall out of the bottom of the cases.

    or possibly the driveshaft splines are worn or in the coupler. becareful looking at the coupler, it could be sharpened up from the splines being worn. dont run your finger in there to fast or else it could cut you. a few ideas to kick around .
    yes.........my nut came flying off

  10. #10
    bowsniper's Avatar
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    Quote Originally Posted by airdog View Post
    I did start it with the drive shaft still in place for about a minute, hpoe I didn't hurt anything. It would not pull out easily, I guess I just need to yank harder.
    I pulled the other heads off and they looked good.
    Checked flywheel it was also good. Removed the exhaust(that was a task due to corrosion on everything) I will now try and pull the cylinders and check the crank. Isthere a special tool for the back cylinder nuts?
    It looks like the motor has been torn down before the cylinders appear to be sleeved.

    Is it possible the noise is coming from the starter bendix? Do they go bad? It seems to make a little noise but maybe that is just because I have the flywheel cover off.
    the bushing where the snout of the bendix goes in could be shot.. its a brass sleeve in there.the bendix rides up n down on a helical gear, it moves the big gear onto the flywheel as it spin the small gear thats connected on the starte side.. not much to go wrong unless it hangs up on the helical gear possibly.. but not likely. it would be more like something gets lodged under the helical gear that prevents it fropm coming all way the dow or up depending on the debris location.

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