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I have a weird noise when I Idle, if the prop is pushing the boat like when I just start, everything is normal, but if I am faster then slowing down to Idle, then I get a weird noise from the transmission, sounds like the gear are lose and playing catch.
At first I thought it was the engine Idle a little rough, but as soon as I go in neutral or the prop pushes the boat all is fine, no noise.
When I'm running everything is normal, same when I'm in reverse. Prop is brand new so is the hub etc.. I didn't hit anything, lower unit is not even scratched yet.
I have a brand new engine, did the break-in and have now about 25 hours, it's a mercury Yamaha 225 4 strokes, had the 10 hour service done. Everything else is working fine.
Quite a few of us here have experienced the "squeeling" from the shaft as you idle along. It goes away when you accelerate. But it can also come and go as it pleases.
Spray some silicone on the shaft as it enters the lower housing. It is located under the main cowling, towards the front and center. The rubber grommet gets dry and squeels for some lubricant.
Someone here has previously posted a pic of it to help with the location. Maybe they'll see this thread and post it again.
Doesn't hurt to do it as part of the reg maintenance, even if it isn't your issue.
It's not a squealing noise, more like the gears are a little loose and the transmission is playing catch with the prop. It only happens when I'm decelarating to Idle from 1000 Rpm. Not when starting from O to Idle, and not when I'm running at speed, not when backing up, and not when decelarating fast.
Only when the boat is going from fast Idle to Idle.
As I said It's a brand new boat, and my first 4 strokes, so compared to my old Yam 150 where the thing was so noisy at idle that I would not have heard anything.
Maybe it's just normal? and I'm just being paranoid
Ive just checked one thing,
When the engine is off, I engage forward, and I can move the prop a little bit, the hub is new. is it normal to have some play in the gear????
I'd recommend taking it to your dealer while it's under warranty. If it is an intermittent or non-confirmable issue, at least you will have a record of it in the system in case of future failure (like when you are out of warranty).
Or, your dealer might just find out what is wrong with it and fix it.
I talekd to my dealer, and it's the normal play in the transmission gear that makes the noise when the boat is going faster than the prop at idle speed.
I used to have a two stroke that was so noisy that I would not have heard anything if the transmission had blown, but now with the 4 stroker, I can hear things that I'm not used to, and since it's a brand new toy, I'm getting a little paranoid.
I have 700 hours on twin F225's and other than the sound like a belt squeal when new, there are no strange noises to be heard. I'd take it back to the dealer until they get it right under warranty.
Get any comments from your dealer in "Writing"!!!!!!!!!!!!!!! If u don`t, u have
no proof that u had a problem, like Mud Runner said,"Take it to the dealer", too
much cash to invest and follow up on a susoected problem..I repowered with a
new 4.3 MPI/EFI V-6 and went nuts when I first took my boat out after the repower, when I got into it, a loud shrill greated my ears, I thought a bearing or
somrthing was locking up!!!!!! Returned to marina asap, contacted my mech. said
lets go for a ride, went 4 a ride and pointed out the noise and started reducing
speed, Dave my mech. started laughing his a$$ off, explained to me it was only
the fuel metering system making the noise that all was fine..So moral of the story,
Get the guy from the dealer to take a ride and point out the problem!!!!!!
Capt.Skid
I talekd to my dealer, and it's the normal play in the transmission gear that makes the noise when the boat is going faster than the prop at idle speed.
I have had the original silver version of that motor since '03 and have not heard or had any issues like that. In fact, the ONLY issue that I have had so far is the squeeling one, which has since gone away since I regularly apply silicone spray to it.
As I said before, get it documented, otherwise if/when a failure does occur, and you are out of warranty, you will be protected.
Get a written work order from the dealer stating the issue, even if he doesn't reslove it.
And BTW, it's a gearcase, not a tranny. The factory guys/dealers will take you more seriously (and will tend to not blow you off) when you use the proper terms. Just FYI...
It is normal. Here is some info I found on the subject:
"Depending on various boat/engine/propeller combinations, there may be a situation where a particular propeller is noisy or rattles and another propeller does not. This noise is a result of crankshaft and propeller speeds varying during rotation due to power strokes. In between power strokes the crankshaft speed slows down due to normal drag in the powerhead, while inertia of the propeller causes the propeller shaft to rotate at basically the same speed. This difference in shaft speed sometimes causes the clutch dog to separate slightly from the forward gear. The separation and contact between the dog and gear can create a noise or rattle. This noise or rattly does not damage the gearcase or propeller and is normally only heard at idle or just off idle speeds."
Sounds like a warm and fuzzy "propeller head" explanation to me.
I don't buy it, but hey, that's just me.
Why does it occur in just a select few? And why would a "particular" prop make a difference when the issue is (supposedly) with the shaft and dog? If there is no tension adjustment to the dog, then why don't all of them do it?
Thanks for the research though.
I guess that I should just be fortunate enough that my 225 doesn't have the problem...
I just swapped my prop on my flats boat because I stuffed the old one into the cement at the ramp (skeg is a LITTLE worn down). It does the same thing. I went from a S/S Prop with a regular rubber hub to the Apollo prop with the slide in hub that is somewhat octagonal with rounded corners. I put it on and it started to make the same type of noise at slow speed. As soon as I give it a little throttle it goes away. I pulled the lower unit thinking I had screwed it up when I stuffed it into the cement (I needed to change the impeller anyway). It was fine. No bad gears, excess play, or anything else (the impeller was Ok too). Major waste of time. I talked to a couple of dealerships and they all said the same thing. When you are swinging a heavier prop with that kind of hub it will make the clutch dog and gears chatter some (like jethro1 said). They said if you fill the gaps in the hub with 5200 it will quite it down a little, but makes replacing the hub later a royal PITA.
I have learned to live with it. I just don't let it stay at dead idle anymore.
weird tranny noise at idle Mercaha 225 
