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Thread: Thrust Bearing on a AT 309

  1. #1
    Member Jimw's Avatar
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    Default Thrust Bearing on a AT 309

    Is there an easy way to tell if a thrust bearing needsreplacement on a American Turbine 309? I am getting a "whine" thatincreases and decrease with engine rpm. I have disconnected the alternator andeliminated that as source. I do have a stainless steel impeller and know theycan be noisy but i really donít think that is it. It is more of a sound like anold power steering pump on a Ford when they started to go bad. There is no lossof performance but the "whine" can be more of an annoyance thananything an would like to have it resolved
    2005 20' Weldcraft Sabre XL 350 MP
    SD309 AT
    2009 Polaris Dragon 800 163
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    I don't know if this will help, is it possible to put water on the thrust bearing to see if the whine goes away. I prefer using oil but it will make a mess. Another way of finding what is causing the whine is use a hose as a stethoscope. Be extremely careful you do not get the hose or hair in any moving parts.

    Is there a grease fitting and it just need to be grease?

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    Member Jimw's Avatar
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    Quote Originally Posted by MacGyver View Post
    I don't know if this will help, is it possible to put water on the thrust bearing to see if the whine goes away. I prefer using oil but it will make a mess. Another way of finding what is causing the whine is use a hose as a stethoscope. Be extremely careful you do not get the hose or hair in any moving parts.

    Is there a grease fitting and it just need to be grease?
    Thanks for the input

    There is a grease fitting that is right behind the "U" joint if that is the thrust bearing it gets greased about every 20 hours as does the shaft bearing at the output nossle. i took it in to a repair shop last year to have the jet looked at and they tor it appart and stated the bearings where good and well greased and didnt find anything wrong with it so i continue to run it. How would i put water on it? Sorry for being uneducated on this. I did some looking around and found this artical on the AT web site.

    2. Moan or whine: The jet unit can exhibit some "turbine whine" not unlike a turbocharger noise but you will know what is usual with your boat. However, if you have a new more obvious moan/whine, especially if it is a very low frequency grumble at idle, that increases with engine RPM's then it is likely to be a rough/worn/water damaged thrust bearing. If water has gotten into the bearing, it is usually as a result of a flooded bilge at some time on a warm bearing, then water can be sucked in as it cools.
    2005 20' Weldcraft Sabre XL 350 MP
    SD309 AT
    2009 Polaris Dragon 800 163
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    I was thinking you could spray it with water or the drive shaft? I use u-tube all the time to find out how to take things apart.

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    Member DanielApplin's Avatar
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    Is there any water coming in the boat under the bearing housing?
    Pull your impeller off and see how much slop is in the shaft, probably shouldn't be more than an 1/8th inch. Or disconnect your driveline and turn by hand to see if you can feel or hear anything unusual.

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    Member c-bolt's Avatar
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    Did somebody swap your pump with a 3 stage??? just kidding, hope you figure it out.
    09 River Wild, 3 stages, LS power

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    Member Jimw's Avatar
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    I have noticed that after the boat sits for in the water for a day or two there is water in the bilge. Not a whole lot maybe a gallon over two days. I will monitor that when I take it out next weekend to the lake for its de-winterization trial.

    I havent checked u tube yet, but you are correct i have watched repairs and break jobs done on u tube and some are very good

    Nope no swap out for the 3 stage. i pulled a hami apart last summer and was suprised at how simple they are.
    2005 20' Weldcraft Sabre XL 350 MP
    SD309 AT
    2009 Polaris Dragon 800 163
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    Member c-bolt's Avatar
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    yeah, simple, but a lot of impellers to wear down and cutlas bearings and sleeves to replace. They chew trash like a boss though.
    09 River Wild, 3 stages, LS power

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