Hi, this motor is about 8 weeks old and has been used 6 times. This is a long shaft motor. The lower unit is making a high pitch noise when in gear and running 1200-1400 rpms. The noise seems to stop when the rpms are above or below this range. I have taken it to my dealer and they say it is a bushing in the leg that supports the drive shaft. The bushing is supposedly located just above the lower unit (not in the gear case). My dealer has already gutted the gearcase and found nothing wrong and had to call mercury to find out about the bushing. Mercury said to grease the bushing and the noise may quit. Mercury said the noise is normal and not to worry about it.
I just got my boat back and have not tested it yet. I assume the bushing will start wining again soon as the grease washes off the drive shaft. This is a brand new motor and this noise does not seem normal to me. Has anyone experienced this? Any advice on what I should do?
singing bushings/bearings is metal on metal. Can't tell me that it's ok.
Course the clutch dog in the lower unit, that does the shifting, takes one heck of a beating; course all those shifter parts are made of extremely high strength material and are submerged in lower unit lube so I GUESS it's ok.
I know they are tough, cause on a resurrection job one time I thought I'd file a tooth......then I thought I'd sand it......then I thought I'd grind it......then I took it to a machinist......and he laughed me out of his shop. :%
Hi Mark, this bushing is not in the gear case. It is inside the leg above the lower unit. I think it is there to stabilize the shaft between the powerhead and lower unit. There is water and exhaust going through there but no oil.
I wonder if this condition will lead to pre-mature failure. Also, it would be difficult to sell my boat with the lower unit wining. Does anyone here know what I should do to get this problem handled?
Guess the 4's are different than the 2's. I'm going thru my service manual for 2's and there is no support mechanism between the top of the water pump and the bottom of the engine for the driveshaft. The drive shaft plugs right into the spline on the bottom of the crank.
There is a lower ball bearing there and a thing called a wear sleeve. The wear sleeve appears to adapt the bottom of the crank to the lower ball bearing that supports the crank. This is all located in the powerhead section of the manual, not midsection.
Don't know why they use a wear sleeve. Usually a shaft just sticks thru the inner race of a ball/roller bearing.......somebody may have goofed up on the dimensions of the bearing or crank.....doesn't make sense.
The mid section is just a hollow casting.
What's confusing me about what you said is the fact that machining and assembly tolerances could build up if there was a support bushing midway down the shaft.
That means that the engine, midsection, and lower unit would all have to be precision aligned......seems odd. You'd have to pin them to guarantee that kind of alignment and for a production outboard, you aren't spending that kind of money.
Also, this bushing would have to accept the crankshaft turning for the life of the engine.
On 2 cycles, the crank is supported in ball/roller bearings which can roll, and are lubricated, hence minimum wear. A bushing, especially when you say it's in the midsection, in harms way (exhaust gasses and water). Usually bushings are brass or bronze and is self lubricating.....but usually have a felt washer that is oil filled.
I know you have what you have and see what you see, but it's amazing to me. Be great if you could show us a picture.
Hi Mark, I am taking the dealer's word on this bushing. I have not seen it. I purchased a new motor so I would not have these problems. I should have purchased a Honda. I will probably have to purchase a shop manual for this motor to find a diagram of the lower unit. This is a long shaft motor so maybe there is some sort of support mechanism with a teflon bushing?? I dont see how teflon could make the high pitch noise? Does anyone here have any experience with this lower unit or have a diagram I can look at??
That thought (extremely long shaft.....25") could have one. Have never been in one that long. Still, what I said about alignment and pinning to guarantee it would hold.
Teflon is soft. Yeah it's slick and doesn't need lube and probably would stand up to the vigors of the exhaust and water, but like you said, it won't squeak. Course, if any crud does get in there it will stay in the teflon. But I doubt that Teflon would tolerate high rpm friction. Know of numerous places where teflon seals are used, but none spin at 6000 rpm's. d
the bushing is located in the mid section just above the water pump. occasionally the drive shaft will rub on it. the F225 and 200's had a bushing update that mostly amounted to a larger ID on the bushing.
most all the jap designed 4 strokes have it and most all the 25"and 30 " motors of japanese decent have one and have had for 20 years or so.
its a bronze oilite bushing in a rubber housing and occasionally they dont sit square in the mid section bore. but the power head and gear case are dowl pin alighned to the mid section.
grease it and retest, if the whine is gone your in the clear if its not have a look at the timing belt and the air box.
if I need the extra clearence a ball type brake cyl hone and a set of snap guages with a 3/8ths drill works well.
imho. it's new, you go mutzing around with it you void the warranty. if it keeps up, go to merc district management, if no luck there go higher. remember the squeeky wheel gets the grease. be firm, but nice.
we all need to support iboats marine store when ever possible. you get, competitive prices. fast shipping, top notch customer service. also it provides us, this great FREE forum.
Rodbolt, my dealer greased the bushing and ran the motor in their test tank for 10 minutes. Dealer said the whining has stopped. I plan to take the boat out this weekend and see what happens. I think the condition will return when the grease washes off. I believe the dealer should give me a permanent fix for this condition. When my kids get a little older I plan to trade this boat for a ski boat. My concern is that it will be hard to sell with the lower unit whining so I want to get it resolved now while the motor is brand new. I feel like mercury should work with me on this.
I finally got to test the boat and the noise is still there. I also notice that there is a "grinding whirring" noise in the midsection of the leg when the motor is in neutral. Has anyone else experienced this with one of the newer mercury 4 strokes? Is there a fix for it?
I can understand your concern,and you have done the best thing.Your Dealer and Merc know you have a complaint/problem.You are logged in there.
I do question you saying it is not audible except at 1200 to 1400 RPM's.I'm not saying you are wrong or anything. But if the noise isn't there at higher RPM's I don't think you have a bearing/bushing problem.Or at least one that is leading to failure.
I failed to mention that now the noise seems to be louder and now does it between 1200 and 1700 rpms. I can hear it again around 3800 - 3900 rpms. I also have the lower pitch grinding noise coming from the same location only when the motor is in neutral. The noise is coming from the leg just above the waterpump.
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Posts: 8,221
Re: lower unit noise -2006 mercury 115 4-stroke
What kind of boat do you have it on? On planing boats, the RPM ranges you mention are rarely utilized.
The bushing in question is a guide bushing only. It's there to keep the shaft from initiating a harmonic wobble which apparently can happen at certain RPMs. Every powerhead has harmonics. Some are worse than others, some are in different RPM ranges than others. The noise you are hearing is the bushing doing it's job. It would be ideal if it could do it quietly, but...
The oil pump for the powerhead is below the powerhead. The bushing needs to be there or the wobbling it's there to prevent could damage the oil pump. That would be a Very bad thing.
Any grease will quickly spin off or wash off. I personally would like to see some of the water from the water pump diverted to it to keep it lubricated with water, but I'm not an engineer. I've often wondered if T-ing into the pee hose and routing a hose down to splash it would be all it would take, but have had so few with the glitch, and once the customers knew what it was, were far less concerned.
No damage is being done. It's just an annoyance. If the motor weren't so darned quiet, you'd never know it was there. As the motor breaks in, it may very well go away.
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Thanks for the input. The motor is on a 22' Crest Tritoon. When I purchased the boat new about 4 months ago it was very quiet. Now I have a buzzing when in neutral and a high pitch whining while in forward. This is my 13th outboard motor and my first 4-stroke. I purchased a 4 stroke because they are supposed to be quiet. I cannot explain how much this bothers me. This newly acquired buzzing grinding sound when in neutral is getting louder. I want mercury to fix this for me. I spent a lot of money on this boat and it is not fair for me to spend my time buzzing and whining all over the lake. Does anyone know someone at mercury that might help me with this? I live in Austin, Texas.
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Posts: 8,221
Re: lower unit noise -2006 mercury 115 4-stroke
You can have the dealer contact the regional service rep. He makes the rounds eventually, but usually can arrange to shuffle the schedule a bit. I can see where a toon might amplify the sound where a runabout would likely reflect some and absorb some. You might want to make sure the prop is good and tight. With such a quiet powerhead, even a loose propeller can make noticable noise. Also, sometimes the prop rubs the ring around it on the gearcase. It's a fairly snug fit when new. It wouldn't be at all unusual for a bit of rubbing at first.
__________________ Hey, Have you seen? They make Really Cool life preservers nowadays.
So "Looking Dorky" is no longer an excuse for not wearing one.
You can have the dealer contact the regional service rep. He makes the rounds eventually, but usually can arrange to shuffle the schedule a bit. I can see where a toon might amplify the sound where a runabout would likely reflect some and absorb some. You might want to make sure the prop is good and tight. With such a quiet powerhead, even a loose propeller can make noticable noise. Also, sometimes the prop rubs the ring around it on the gearcase. It's a fairly snug fit when new. It wouldn't be at all unusual for a bit of rubbing at first.
i just bought the same motor last summer. got about 25hrs. on it. so far so good.
I spoke to Mercury customer service today and advised them that the motor is still making the noises described above. Mercury instructed me to take the boat back to the dealer and tell the dealer to call tech services for advice on where we go from here. I got my fingers crossed!!!
Good Luck Machici, hope you have better luck with your motor.
Willy - I torqued the prop nut myself (50 ftlbs) if I remember correctly.
Update-
The dealer and I went to the lake and drove the boat. He listened to the noise. Dealer said the mercury tech rep will be in town on 2/13 and will ask about my problem and see what they will do. Dlr said they may take my boat back to the lake with the Mercury rep. I will give an update soon.
Spoke to dealer today and the mercury rep will be in town 2/20 or 2/21. Previous merc rep was in town only to give a class to technicians working at the dealership. I am going to try and be present when the rep listens to the motor. I will post follow-up soon.
lower unit noise -2006 mercury 115 4-stroke
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