When drive is trimmed up, bellow not connected.

06Rinker270

Hey everyone,

When I was replacing anodes the other day I trimmed up the drive and saw a bellow(believe its the exhaust, underneath the shaft bellow) in the center that separates form the drive.  When I trim down it goes back into place.  Is this normal?   I wish I would have taken a picture but I believe some of you may know what I am referring to.  Picture below is a google picture that may help understand what I am referring too.  2006 Bravo 3.  Thank you

craigswardmtb

That's normal.

06Rinker270

water cant get in?

Handymans342

I dont think thats normal myself.

craigswardmtb

Right. As I understand it Merc uses internal exhaust flappers that "helps" prevent water ingestion at low rpms. And more importantly there should be tall exhaust risers that help prevent water ingestion. At high rpms the exhaust pressure won't allow water to come in either.

frenchship

It all depends of the type of exhaust bellows that it on. Look at this picture.
if it is the one on the left it is ok, if it is the on on the middle it should not come off.

craigswardmtb

Also good practice is to try not to ever come off plane abruptly from high speeds. This leads to a large wake that wants to push water up the exhaust of your low positioned engine and into your cylinders. Again tall exhaust risers help with this problem.

Cableguy Greg

It is called a cheater tube for the exhaust. In the picture that @frenchship posted, it is the one to the left of Michigan. The one above 'ch' is the full exhaust tube. The full one directs all of the exhaust thru the prop, where the cheater tube directs it thru the prop when the drive is trimmed down, but lets it out when the drive is trimmed up and on plane. Almost thru hulls. ;-)

06Rinker270

I will have to look again but I believe its the one on the left of Michigan in the picture.  Ill have a look tomorrow morning.  Appreciate it.  

youstolemybeer

its normal. at idle with the outdrive down, the exhaust is routed under water, when running on plane the exhaust is routed out above the water for more power. 

Robyw1

No that is not normal. The exhaust bellow should always be securly connected to the out drive. You can probably tighten it with the clamp and it doesn't require bellows adhesive like the driveshaft bellow. But it should always be secured to the drive. 

Cableguy Greg

I just read somewhere that on a B3 drive, Merc uses the "cheater tube" and not a full exhaust bellows. Unfortunately I can't find the link...

Stodge

I saw the same thing and asked my mechanic. On my old boat with alphas the exhaust bellows was always connected.  But on my B3s they have the cheaters also.  

frenchship

Mine came from factory with a complete exhaust bellow not the cheater type and two other Rinker at our marina has the complete exhaust bellows. The cheater type is an option that give you a bit more power but more noise. In the Mercruiser service manual they show both 
system. Your choice

JoeStang

Thats interesting. I definitely wouldnt like them open when trimmed up since I do a good amount of "skinny water" anchoring, so I have the drive trimmed up quite a bit. I'm gonna look at mine before it goes in the water and see if they're open or closed when trimmed up.

06Rinker270

Stodge said:

I saw the same thing and asked my mechanic. On my old boat with alphas the exhaust bellows was always connected.  But on my B3s they have the cheaters also.  

Stoge, yours is not connected either right? What did mechanic say?

rinker312

the exhaust bellows have a tendency to come off like that because they are on the bottom and when you raise the drive up they have a lot of pressure pulling on them.  I have pulled my boat out of the water on multiple occasions to find that they are off. I have replaced them with bellows adhesive but they still come off. I do not believe that there is any reason that they have to be on.  Whether they are on or not the exhaust is still wide open to the water there are no flappers inside the drive anywhere. Now if your drive shaft bellow came off then you've got a problem!  

Mike_G

Frenchship's post is the answer here. All Bravo 3s that I have seen have the "cheater" bellow. -=Mike G.

rinker312

My bravo 3s do not have that cheater. Wonder if they started that after a certain year. 

howardrams

06Rinker270's answer is that his is normal if he has the rubber boot shown on the left in the picture Frenchship posted.  It's hard to see on his photo.  My new 2014 B3 has the 8" rubber boot clamped on the drive end and just slips over an oval shaped tube on the transom end when down.  If he has the much longer bellows that accordion out as the drive moves up and down, I would think those would be clamped on both ends.  Just can't tell from the original photo.