yamaha F90 prop chatter

Hi all, just wanting to know if anyone has a 4stoke engine and has experienced prop chatter?(engine hours 38 and 19 months old,with standard alloy prop)
i was flushing my engine,and decided to just put it gear still on 700 rpm and i could hear a rattling noise coming from lower leg area near prop.so increased rev to 800-900 rpm and the noise disapeared!.so i went down to my dealer showed them the video and straight away they said most likey prop chatter.they said take the prop off and run it. if you hear NO noise then it is definitely prop chatter.so i did this and they were right, prop off running NO noise.so last time i took the boat out i don't remember hearing anything like this with engine in water.on Monday i will contact dealer and let them know the out come,so i guess the question to them will be-Will prop chatter cause any damage to my gearbox?
any feed back or experiences most welcome

cheers
kuz

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Kuz


ranmar850's picture

Posts: 2702

Date Joined: 12/08/12

Not in my opinion

Sun, 2019-04-07 08:23

 I'd like to hear others opinions on this, but prop chatter is not unusual, or damaging to the lower unit. My Merc 150 didn't do it with the 14.5 x 17 Enertia, but it now does with the 15 x 15 Enertia. Of course, you are probably running a rubber hub in your Yammie, I have a flo-torque inset type. You see a bit about this on THT from time to time, recommendations for ridding you of it usually revolve around trying a different type of hub. 

Now you said it was doing it while it was flushing, not in the water. Have you tried  it in the water since then? Loading is much different when you have it in gear pushing water vs spinning in air, it may not even be there in the drink. 

Posts: 57

Date Joined: 28/02/15

thanks ranmar850, i have not

Sun, 2019-04-07 08:51

thanks ranmar850, i have not tried it in the water since,but didn't hear anything last time out.
kuz

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Kuz

scubafish's picture

Posts: 947

Date Joined: 15/08/12

Check the balance

Sun, 2019-04-07 09:51

I would get them to check the balance of the prop,ali still needs to be balanced could be a dud one .Un balanced prop will do damage over time.

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quadfisher's picture

Posts: 1145

Date Joined: 28/09/10

Do it prop (ly)

Sun, 2019-04-07 15:36

 I have just done some prop testing of my own , with a f70 yammy. 

 Its on a heavy for size haines profish, and I read up even before purchase that the combo reqs careful propping. 

 It came 2nd hand to me , with a sort of standard k series 13 3/4 x 13 pitch prop.

 On sea trials when purchased it was just wrong ( old mate original owner had done 40 hrs in 6 years!) the motor had some vibration and lower and higher noise 

 pitchs that were annoying, as well as dropping off the plane far to easy and no guts on take off. 

 I researched and found out yamma do a k series prop in whats called a pontoon series with larger ears to prop which they say you need to drop a couple of pitchs down  , and comes

  standard with the shift dampering hub as well, in alloy.

 $170 ish from chivers it was worth a try. I got a 13 1/2 x 10 1/2 pitch , takeoff was great , held plane perfect even at 12 knots or less, and bingo no more funny pitch noises or vibrations.

 However it did use more juice and ran out of legs too easy as well as being a bit too revvy for my liking.

 I then picked up the 13 1/2 x 12 pitch pontoon s.d.s and finally its done. great economy , good takeoff , no vibrations , good speed at comfy revs . 

 I sold the original k prop off , and now have my perfect prop with the near new pontoon x10 1/2 as the spare for trips away, or if I feel like pulling a tube for the girls.

 Yes it took some expense and time but gee it makes the boat from good to great, very happy.

 

 

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quadfisher

Posts: 57

Date Joined: 28/02/15

hey guys thanks for your

Sun, 2019-04-14 06:52

hey guys thanks for your input.spoke to the dealer very common,for a non sds prop. and will not damage gear box.

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Kuz

carnarvonite's picture

Posts: 8621

Date Joined: 24/07/07

No resistance

Sun, 2019-04-14 07:30

 The chatter is due to no resistance on the prop, its only chatter on the splines, nothing to worry about.

Posts: 57

Date Joined: 28/02/15

thanks carnarvonite thats a

Mon, 2019-04-15 20:09

thanks carnarvonite thats a good way to explain it,im staring to understand it a bit better.

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Kuz