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ryan04wakesetter

Prop rotating when engine is in neutral

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ryan04wakesetter

Hey Everyone,

I have an 04 Malibu Wakesetter Direct Drive and the other day when I was flushing the motor, I noticed the prop was spinning very slowly. The boat was in neutral and I popped it in and out of gear to make sure. Does anyone know what may be causing this?

Thanks

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WakingMeHappy

Could it be it's just free spinning from vibration? Is it something you can actually (safely) grab and stop? If you can do this and not feel any force I would think it's just caused by vibration.

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Bake's Marine

We see this time to time when we run boats in the shop, it's usually a good sign that the forward or rear clutch in the transmission is start to show some signs of wear. When the clutch gets glazed it tends to not released 100% and leaves the prop spinning. If it is really cold I've seen it do this too and it will stop once the gear case gets a good chance to warm up.

If it is spinning really slow, you can try to stop the coupler (be really careful with how you choose to do this) Hold it stopped for a few minutes and let go. Sometimes the issue will go away if the wear to the clutch is minor, Once it warms up it will release. The only other way to fix it is to replace the clutch and depending on age or damage a gear box rebuild runs from $600-$1,000 (not including labor to remove and replace from the boat)

Back in 2000-2002 when factory ballast and additional weight started to become really common for customers to add to their boat. We started to notice a lot of transmission issues and failures. This doesn't apply to the guys that just water ski full time but if you use the wedge or ballast, i highly suggest transmission service be done every 50 hours when you change the engine oil. Make sure fluids get changed prior to winter storage, allowing old or dirty fluid can allow impurities or moisture to separate from the fluid causing severe corrosion inside the gear box or engine oil pan.

-Paul

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Wayne

Our transmissions are similar in design to traditional automatic transmissions in cars. However, we just have forward and reverse. The clutches are bathed in oil, this oil causes viscous drag on an open clutch. It's similar to wet dishes in the sink or a wet glass on a really smooth non porous surface. It kind of sticks. Since the input of the transmission is spinning "half" of the clutch, the viscous drag from the oil transmits a small amount of torque to the other side of the clutch to the output side of the clutch. If that torque is greater than the bearing, gear, seal, stuffing box and strut bearing drag then the prop will spin.

When the transmission fluid is cold the viscous drag effect is greater because the oil is thicker. As it warms up the viscous effect reduces as the oil gets thinner (change in viscosity).

The reason it usually spins in the forward direction is that for reverse tourque must be transmitted through a reversing gear set. This has enough drag to over come the viscous drag on the reverse clutch.

Yea, I know I'm a nerd, but I engineer transmissions for a living.

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Woodski

One other item, the newer style strut bushings are much lower friction that the older ones, thus allowing the shaft to spin much easier. Those would be the white vesconite ones.

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85 Barefoot

To OP, with boat in water, watch driveshaft and see if it does the same thing (continue to rotate). If so, tap reverse and go back to neutral. Does it stop? If so, I'd say not much to worry about. If not, then some adjustment could be in order. Both of my boats spin the prop AFTER coming off plane, but stop after tapping reverse. Have had no issues, including one with well in excess of 1200 HARD hours with 454-torque.

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