posted 11-30-2004 05:44 PM ET (US)        

I wrote to Mercury Canada and was told that this grinding noise was "normal", however they were aware of some similar complaints and the engineers were working on the problem. The motor has only 84 total hours on it! You can hear the whirring and grinding noise from 30 feet away and guests on my boat frequently comment, "Is it supposed to sound like that?"

posted 04-04-2005 01:42 PM ET (US)            

My new 2004 Mercury 90 hp four-stroke - mounted on a Montauk 170 - does the same thing you describe, which is incredibly aggravating. I have had it to two dealers because I wanted a second opinion, but the solution has not been found. The first dealer thought it was something to do with the exhaust. The second dealer - not a Boston Whaler shop - said he thought it must be a "Whaler" issue because he'd never heard that noise before on any Mercury 90s or 115s.

Funny enough, I also have a 2004 115 hp four stroke - essentially the same engine - and it doesn't make the sound.

Thoughts or recommendations from any of you Whaler experts?

posted 04-08-2005 11:58 AM ET (US)            

My 2004 90 does the same as you describe - and yes, the noise goes away completely when you put it in gear.

posted 04-09-2005 11:37 AM ET (US)            

your 115hp merc 4 stroke has a drive belt that turns two cam gears off the crank shaft.

have your ever heard a noisey fan belt..or the drive belt on a supercharger at the drag strip? How about the drive belt on a harley?
could be one possibility

also, grinding only in nuetral, an improperly adjusted shift cable at the shift platform can cause this. ideally, when running the motor on a flush attachment..the prop will not be spinning. not always the case tho. it is a fine adjustment to get the shift platform properly adjusted @ the nuetral safety saftey switch[ not its actual name]
so the right amount of pre-load is set. mercury's instructions

have your dealer check it next service

posted 04-11-2005 01:20 PM ET (US)            

According to the service manager, the noise is coming from the drive shaft running from the power head to the prop. When there is no load on the shaft and gears, i.e., when the motor is idling, the shaft is rattling around in the lower unit. Putting the motor in gear "binds" the shaft against the gears and noise goes away. The service manager says all outboards make this sound.

As this 2004 four stroke 90-hp is approximately my 10th outboard motor (but first four stroke), I asked why I haven't heard this sound before. The explanation was that the noise eminating from two stroke power heads masks the drive shaft whining/rattling. With four strokes, the power heads are so quiet that you can hear this - and other such sounds much more clearly.

Apparently, Evinrude has a factory "fix" for this problem by running some kind of plastic sleeve down the shaft, which reduces the amount of travel that the shaft has inside its housing. There is no such "fix" from Mercury.

posted 04-11-2005 01:26 PM ET (US)            

Yamaha uses the lower end from the v6 motors .
Merc uses the yamaha powerhead but use their own lower ends.

posted 04-11-2005 02:26 PM ET (US)            

As mentioned, I also have a 2004 Mercury 115 hp four stroke mounted on a Dauntless 16 and there is no such noise at idle or any other time. The dealer explanation is that the motor is mounted much lower in the water on the Dauntless as compared with the 170 Montauk, so you can't hear the lower unit as well. Yeah, right....

BTW, the dealer drained the lower unit oil in the 90 hp to see of there were any metal flakes in the fluid that would indicate metal on metal friction inside the unit, and there was no such evidence. They saved the gear oil in a jar and showed it to me when I picked up the boat. Of course I had that fluid changed at the 10 hour checkup and think any related issue would have been spotted at that time. The idling noise started with the first key turn and the motor now has a whopping 15 hours on it.

posted 04-11-2005 06:18 PM ET (US)            

the driveshaft is connected to the crankshaft in the engine block dirrectly via "splines"
as long as the engine is running the driveshaft is turning the same speed. [rpm]

if you look physically at a drive shaft of a 4 stroke as compared to the drivshaft of a two stroke..a. you will notice there is more metal in the two stroke verses the four stroke. also the number of slplined teeth is different.

as long as the driveshaft is spinning[engine running] the water pump inpeller is being turned also to cool the engine block.

my point is..this is nothing like automotive. its a marine outboard.engine running driveshaft is always turning thus under a minimal load.

lower unit rattle...nature of the beast for now...until a better mouse trap is built.
trgards .
terry

posted 04-12-2005 02:42 PM ET (US)            

they...the 4 stroke and the two stroke Optimaaamax have the same appearence..but are not one in the same...gear ratios [gears]..and driveshafts and and a few minor details are different.

I personally have seen just how much these driveshafts flex under load. I have seen them break also. sheared right in two. I feel the 4 stroke version flexes more than the two versions. possibly due to more torque being applied. Due to the flexing the four stroke shafts have been machined in certain areas to prevent rubbing on the exhaust housing.

posted 08-02-2005 11:18 AM ET (US)            

Did you finally get an answer (solution) to your grinding sound problem because I have the same engine with the same problem?

Thanks John

posted 11-26-2005 08:03 AM ET (US)            

To update my situation:

The dealer last removed the bottom end and made up a shim to be placed in the lower unit's bearing race? This was an attempt to stop side to side movement of the gears. He reasoned that the bearing surfaces had worn and this was allowing latteral movement which lead to the grinding/whirring noise at idle. It didn't work! In fact I think it made it worse. So the dealer has the boat again for storage this winter and is again in contact with the Mercury Rep. Our boating season is so short here that I still only have 80 hrs use on this engine in 4 years!

Thank you all for your suggestions and recomendations but please remember that this noise was definately NOT there when the engine was new and only appeared after 2o hrs use.

posted 11-26-2005 10:19 AM ET (US)            

It is a bit ironic, but in the 2006 Mercury outboard motor catalogue the page which deals with this engine has highlighted only two special features for it. One of them is:

posted 11-26-2005 11:51 AM ET (US)            

I can't take any personal credit for repowering my first and second Whalers with Yamaha four strokes, since my local dealership (which also sells and services other brands) almost twisted my arm off to go Yamaha, but after a total of well over one thousand hours on the two motors in three years--without a single problem--I'm sold. By the way, the dealership owner is an offshore fishing addict and only runs Yamaha motors on his own boat, for whatever that's worth.

posted 02-28-2006 01:09 PM ET (US)            

The Yamaha F115 weighs fifteen or so pounds more than the 'same' Mercury motor...I suspect that extra weight might well be found in its sturdier, apparently better designed lower unit. I've never heard of this particular problem occurring in a Yamaha F115--I've certainly never experienced in mine after more than 700 hours of use--and I'd sure raise hell with the dealer and the manufacturer if either tried to tell me it was 'normal.'

posted 02-28-2006 02:15 PM ET (US)            

I've lost count of the number of times that I've tried to start a running Honda or Yamaha. A little noise might be a good thing.

posted 03-04-2006 09:05 PM ET (US)            

Seems to me its an adjustment on the throttle.

posted 03-13-2006 03:51 PM ET (US)            

I'm still waiting on the Mercury rep to call me. I guess he must be afraid to call when all he will tell me is the noise is normal and there is nothing Mercury will do. I mentioned to my dealer the cable adjustment fix and he just poo-poo'ed it, as he believes the noise is coming from the runnout in the lower unit's bearing.

He did however admit thay there are ALOT of these complaints reguarding said noise on these units.

posted 08-23-2008 04:10 PM ET (US)            

We call these new motors the Veradito motors because they use some of the same components as the VERADO motor. The displacement is the same and the engine block dimensions are the same. It is likely there are some shared components.

The Veradito FOURSTROKE motors are also sometimes unofficially called the L4NA motors, as in in-line four cylinder naturally aspirated.