Just went for a bay test on the new 240 and from the moment we started the engine I could hear an exhaust noise that I was not familiar with. When we pulled the boat I noticed that the bellows was missing?? I was told this was a new design where a rigid male piece on the lower unit mates up to a soft collar on the transom section when the outdrive is lowered into position. I wouldn't accept that style and insisted they install that standard accordian style bellows that is on every other BIII I could find. The engine is noticibly louder at idle whereas my 2002 5.0 B3 setup was extremely quiet at idle. Anyone else have any experience with this??
Missing Bellows?
- Thread starter jg300da
- Start date
RiverRat
New Member
- Apr 1, 2007
- 1,137
- Boat Info
- 03 280 Sundancer
Kohler 5 KW Gen.
95 13' Boston Whaler Dauntless
- Engines
- Twin 4.3 MPI
Alpha 1 Gen 2
Never heard of such a thing... What does it sound like when you trim the drive up to get a good cruising attitude. Seems like if you trimmed the drive up at all it would sound like through hull exhaust. :smt017
lorenbennett
New Member
Have always wondered why mine is so noisy testing in drive way. :wink:
The newer design Bravo III drives have what they call an "open bellows" which is what you observed. The bellows is only connected at one end. I had the older design B3 drive on my 240 Sundeck and my 260DA has the newer B3 drive. I don't notice that much of a difference in overall noise between the open bellows and the closed bellows but there is a bit of a difference in the way each one sounds and that may be what you experienced.
One nice thing about the new B3 design is they shift so much smoother than the old ones ever did. I really like the new model much better than the old one.
One nice thing about the new B3 design is they shift so much smoother than the old ones ever did. I really like the new model much better than the old one.
Thanks Dave, good to know I'm not imagining things. I agree the new BIII shifts much more smoothly. I think that they change the idle speed slightly, lowering it, whenever you shift which also helps make the shift smoother, have you noticed that?
boatrboy
Well-Known Member
I had my bellows replaced by a dealer 2 years ago. When I checked his work, I freaked out and told them they forgot to install the exhaust bellows correctly and even left the clamp off! The owner explained that the newer models don't use this but a new "Tube" replaces it. I researched it and found it was true, it is even shown in the Mercruiser manual. Realistically, the outdrive would have to be trimmed up quite a bit to leave the tube, so I don't think it really is much louder at idle speeds IMO.
BTW - I replaced an alpha bellows set on a boat I worked on. I used the tube for the exhaust with no noticeable increased noise level.
Mark
BTW - I replaced an alpha bellows set on a boat I worked on. I used the tube for the exhaust with no noticeable increased noise level.
Mark
I spoke with a tech at Mercruiser yesterday and he told me that they were using that new open style on "some" Bravo3's. He couldn't specify which ones or why, he did say however, that dealers were getting a lot of complaints from new boat owners about the level of exhaust noise.
boatrboy
Well-Known Member
If I remember correctly, the clamps on the exhaust bellows/tube can be easily accessed so changing it should be no big deal.
BTW- I remember when the guy who did my bellows replacement he showed me a Volvo and they have either a slit or cutout in the exhaust bellow.
BTW- I remember when the guy who did my bellows replacement he showed me a Volvo and they have either a slit or cutout in the exhaust bellow.
This is intended to relieve back pressure at high engine rpms or in neutral, when there is no propeller action to help move the exhaust. So, at idle it may exhaust easier through the new design, rather than being forced down lower in the water to exit through the props. Once in gear, the prop should help suck the exhaust out through the prop wash.
Update:
After speaking with Mercury they agreed to send me the bellows at no charge but would not pay for the labor to install it. They also gave no reason for the design change other than to call it a "performance enhancement" Sounds like BS to me as every other 2007 boat at MM had the closed bellows from the factory. After installing it (not an easy task) I finally launched the boat and all I can say is what a difference! Much quieter. Definitely worth the effort, and no effect on the warranty.
After speaking with Mercury they agreed to send me the bellows at no charge but would not pay for the labor to install it. They also gave no reason for the design change other than to call it a "performance enhancement" Sounds like BS to me as every other 2007 boat at MM had the closed bellows from the factory. After installing it (not an easy task) I finally launched the boat and all I can say is what a difference! Much quieter. Definitely worth the effort, and no effect on the warranty.
