Bravo Noise
 

I have a noise that is concerning me. At idle my 502/mpi Bravo makes a noise that sounds like a clunk clunk clunk at the transom. not consistent but noticeable when flushing motor and hood up and idling low with a slight lope.
I had a whine that went away when I greased the Gimbel.
No noticeable slop from forward to reverse.
What do you guys think? Normal?
Thanks

Re: Bravo Noise
 

This may sound like a dumb question but do you have tru transom exhaust? if you do have you checked to see if it is the internal flappers, they tend to be louder wehn the boat is on the trailer, the water contacting the hull deadens the sound when you are in the water. If not I know Mercruiser was having a problem with the shift plate in the drive contacting the outside of the brass portion of the gears in the upper that seats around the cone clutch. When I went to Merc tech education last winter the instructor more or less told us that they knew about the problem but hadn't found a cuase and it isnt a long term problem.

Re: Bravo Noise
 

hillbilly24 could be right about those flappers. My engine makes a clunking sound that turned out to be the flappers

Re: Bravo Noise
 

If the drive is trimmed up you will hear the ujoint clunk. It may be the exhaust flappers,,,, worst case,,,,,, its a gear with a tooth missing.

Re: Bravo Noise
 

It's normal, they make a clunking noise when there is no load.

Re: Bravo Noise
 

Thanks for the reply
Strait through transom exhaust. No flappers that I know of.
The rest is admittedly above me :-)

Re: Bravo Noise
 

Ok I like this answer :-) haha
I live in an area where outboards are the norm and very few go fast boats. I feel like the midas comercial sometimes discribing this noise. But it is a thump or dull slap sound like the sound a manual trans makes when the motor is idle low and lumpy and the gears clunk together except lower in tone. Does not sound like internals more like coming from shaft area.
Thanks again

Re: Bravo Noise
 

The clunking is from backlash when there is no load on the drive.

I can relate, back in 1988 (when the Bravo was released) there were very few performance boat here in Maine . The clunking sound was driving me nuts and I had two different shops completely tear down my brand new drive to find nothing wrong. We finally reached someone from Merc who told us that it was normal under no load conditions.

Kurt

Re: Bravo Noise
 

Wow I bet that it was an eye opener for the mechanics that thought it was a problem and you think merc should have a sticker desinged to say Warning ...this drive sounds like hell but run off shore with confedence it is a Mercruiser :-)

Re: Bravo Noise
 

I have a Volvo Penta and it uses basically the same upper gear set-up and mine also makes noises some times when running on a flush tee with no load. I almost took it apart before I figured out (with the help of this kick as% web board) that it is normal for some of them to do that. Whew.
As a related story ........I once was a going to buy a consignment boat from a local parking lots dealer and it made a noise that I thought was the counter balancer gear train (it was a Mercruiser V6) and I wanted a 3rd party shop to check it out. The dealer bought the boat and I am sure he raped the guy who sold it to him. Anyhow, the guy would not let me do a compression test and check it out but agreed to let a 3rd party guy do it. I picked a authorized Volvo Penta repair place to inspect the boat, this was a task sorta because it was before I knew the wealth of information here and I always do my own repair work so I didn't have any repair guys I knew/trusted. Anyhow found one and they seems OK and they charged me 175 bucks for the "check out". They said hey heard a noise that was maybe the gimble bearing. I never heard any noise but the dealer who owned the boat agreed to pay for the gimble bearing replacement so what the heck. At this point I was going to buy the boat and the shop replace bearing and the noise remained so they talked the dealer who owned it into letting them tear the drive apart for the noise I never heard. The messed it up HUGE. The shop manager they never took a SX drive apart.. They had the backlash all hosed up (I think that is what they did anyhow) and it sounded like it was getting hit with a large hammer when the shafts were turning. Then the dealer who owned it tarted talking about lets talk about splitting some if the huge costs we were about to get into. I just walked. In what I know now, I would bet good money that the repair guy heard the ilde no load clunking and then it went down hill from there since he did not how to set up a drive.

Re: Bravo Noise
 

Great story that also seems to be very common. I have tons of background with car race engines and trans/rear setup but outdrives are all new and I admit scary. It is great to have this site for info

Re: Bravo Noise
 

Yea, I was the same way, have done lots of automotive and a couple transmissions and was scared of the outdrive. I took the leap and rebuilt an alpha one for our old boat and it was not that hard. You do need some specialized tools and setting up the bearing preload is PITA because they shim the assembly under a pressed in bearing cup,(stupid design) but all and all not that bad. Definitely need a good manual and the factory ones are very reasonable in price. I buy a good manual for anything mechanical I own.

Re: Bravo Noise
 

If you dont have some form of internal or external flappers you really should consider inatalling them they prevent reversion when you jerk the throttles back and that big ass wake slams your transom.

Re: Bravo Noise
 

Be sure the spline coupler has grease. If it is dry it will cause this. There is a grease fitting on the back of the engine, where the drive shaft meets the coulpler.

Re: Bravo Noise
 

That was it ! Quiet as a mouse ( sorry small block guys )
Took about 20 pumps for it to start oooosing out of the fitting so I guess it was dry. Took it out for a test and no noise.
Thanks guys