Prop loose / play on shaft

[3ceHutch]

Hello Malibu Crew,

I'm very new to owning & maintaining a direct drive ski boat.  Our "new to us" 95 Response has been running great all season - trouble free!  This has been our first full season.

Last night I pulled the boat out of the water and have it now on my trailer. While inspecting the rudder & prop, I noticed the prop has some play on the shaft.  I can actually rotate / wiggle the propeller slightly - just a few degrees each direction & without a lot of force or effort.

I obviously would think this is not normal. I cannot be certain, but I don't think I have experienced this before.

Also, to note - I have not performed any work or service on the prop.  I believe it may be the original prop;  it's a stainless 3 blade.  While running the boat, I cannot hear any banging sounds when shifting neutral to forward or neutral to reverse - no unusual sounds while docking and bumping into reverse.  Also prior to loading on my trailer,  I ran the boat yesterday trouble free & even a short WOT run.  We float the boat onto the trailer, no power loading required on my ramp.

I'm assuming the shaft key maybe broken?  If the prop is loose on the shaft now, I'm wondering if I would even need a puller to remove the propeller & replace the key?

Any crew members see this before? Any suggestions?

Thank You

Hutch 

 

[oldjeep]

Yeah, sounds like the prop is just loose.  Take the nut off and see if the prop comes off.  Check the key for damage and if it isn't - put it back together.

[Bozboat]

Then buy an acme 3 blade. They are CNC designed and cut out of brass material called nibral instead of cast aluminum. More efficient prop and it should save you by absorbing the impact when you hit something saving your prop shaft and other parts. I learned this the hard way.

Edited September 6, 2023 by Bozboat

[justgary]

Remove the prop, then put it back on the shaft without the key.  Mark the position of the prop on the shaft, then remove the prop again.  Now install the key and the prop and verify that the prop goes all the way to the marked position on the shaft.  If it doesn't, the key is too tall and you need to grind or file it to fit.

[Woodski]

+1 on what @justgary posted, also it is easy for the key to slide forward during prop install to hold the prop back from a full seat on the shaft.  Make sure the key is in good shape and if you need a replacement, brass or stainless only.  A new nyloc nut and retaining cotter key will ensure your prop does not end up at the bottom of the lake.

[3ceHutch]

Thanks for the feedback - great advice!

[boardjnky4]

I'm having this issue on a much newer boat, and what we are finding out is that there is seems to be a blemish which has occurred on the prop shaft. Possibly from a prop nut which came slightly loose over time. Now there is a slight "bulge" on the shaft and the prop doesn't sit correctly.

[TomH]

Get some valve compound and lap the prop to the shaft.

[oldjeep]

7 hours ago, TomH said:

Get some valve compound and lap the prop to the shaft.

You are going to need to explain how that would work.  Hardened steel prop shaft, lapping compound and a prop made out of butter.

[justgary]

10 hours ago, boardjnky4 said:

I'm having this issue on a much newer boat, and what we are finding out is that there is seems to be a blemish which has occurred on the prop shaft. Possibly from a prop nut which came slightly loose over time. Now there is a slight "bulge" on the shaft and the prop doesn't sit correctly.

Please post a photo of the shaft issue.

[boardjnky4]

2 hours ago, justgary said:

Please post a photo of the shaft issue.

Well, hate to say this but I think it’s been misdiagnosed.