Bang/pop noise

[Galaxy24]

I have a 2013 Z1. About a second after I start to push the throttle forward to pull the rider out of the water is when it occurs.

I cant feel it through the boat I can only hear it.
It is faint as myself and only the other driver has heard it.
It does it 100% of the time when pulling a rider up out of the water.
I will hear it towing an adult wakeboarder with some ballast and even with an 80lbs wakeboarder with no ballast.
I haven’t heard it when accelerating from a stand still when not pulling a rider.
Sounds like it is coming from the engine compartment
The fluids are clean at at the proper level in the VDrive, trans, and engine
It doesnt sound like it is coming from the tower but next weekend I am going to pull from the ski tow just to test.
If I have the opportunity next weekend I am going to open the floor board up when pulling the rider up and see if I can pin point where it is coming from.

Has anyone else heard this before? Any suggestions?

Thank you.

[Z1owner]

So here's a long shot.... The flippable tow hook / anchor light assembly on my '015 Z1 tower won't stay latched in the tow hook position. When the rope goes slack, the assembly will sometimes rotate off the stop then will "bang" when the slack comes out of the rope and pulls the assembly back to the hard stop. I've not been able to get the latch to work right so I just glued a rubber washer / cushion on the stop and it has eliminated most of the noise. It obviously doesn't do it if there's no rope / rider attached.

[Galaxy24]

Thank you for the suggestion Z1. I had the same issue and took care of that the same way. This is a different sound.

[JohnnieMo]

Check that your prop shaft is tight on both ends. Maybe it has some play in it. When you add throttle it re-seats itself. Maybe???

[bait28]

Take a look at your prop shaft where it passes through the strut. Look directly in front and back of the strut specifically at the prop shaft. Does the prop shaft look shinny about 1/4 of an inch in front or in back of the strut? Or is it dull and consistent up and down the shaft.

[Galaxy24]

bait28-There is a definite polished section and a dull section between the strut and the prop. I included an image of it. The image does an ok job showing it but in person it is very clear there is a difference.

What would you recommend?

If there isn’t any damage is all that is required is torquing the bolts that attached the prop shaft to the VDrive? I will check
the strut to make sure it is tight also.

Is there anything else that should be inspected?

[bait28]

What does the shaft look like at the other end (non prop end) of the strut

[Galaxy24]

The non prop end of the prop shaft is dull. It isn’t shiny or polished.

[NG572]

I have a similar clunk under acceleration, happens after I have been in reverse. I assume this is the prop sliding on the shaft? However, the prop nut is very tight. Thoughts?

[Galaxy24]

Could it be that the prop shaft is actually sliding back and forth? Is that normal to some degree. I am guessing not. Since the polished portion of the prop shaft is in between the strut and the prop this is telling me that the prop shaft is moving forward towards the bow of the boat. So when I accelerate the prop is pushing on the prop shaft to propel the boat forward and the prop shaft is actually moving forward into the boat. I am guessing the banging noise I am hearing is when the prop shaft can no longer move forward.

This is my first VDrive and I have never seen inside of one but that is what my non experienced VDrive mind is telling me. What do you guys think?

[bait28]

It is possible that is where the noise is coming from. You can also check the shaft travel by looking at the vdrive while someone shifts into fwd and reverse. There should be no travel in the coupling assembly.

[Galaxy24]

I will get it out on the water and test as soon as I can. I will let you know what I find out. I measured the polished area. It measures 1/8”.

[Galaxy24]

JohnnieMo-I will check both ends. I checked the prop side only so far.

[Galaxy24]

I checked the nut on the coupler side. It is tight. I was hoping it would tighten and pull the gap out. Guess not.