exhaust bellows vs tubes

[roger275]

We drove the boat from Galveston to Stuart FL last fall and when we pulled it I noticed the exhaust bellows were both loose on the transom side. A trusted mechanic said this happened often and I could leave them that way since they were a pain to fix. We came back this spring and just returned after going to Washington DC. We pulled the boat there and I showed it to a mechanic at that marina. He told me about a retrofit of "exhaust tubes" instead of the bellows.

We've run many hours the way it is so would like comments from anyone running with them off (like us) or with the tubes retrofit. Please supply part #'s for the tubes is anyone has them.

 

[65chevelless]

check out sterndrives.com. you may have to do a little searching in the website but they are available seperately

 

[FYN409]

While I do not have any part numbers, I believe I have the "tube" you are referring to on my drive. Essentially it’s more like a rubber sleeve about 2" long that sticks out of the transom and "seals" against the drive when it is in the down position. I have been running this for 3 years and have had no issues with it. It sure makes inspecting the u-joint bellows easier! I do not know what advantage one has over the other. This is the first boat I have had like this, all the rest have had full exhaust bellows.

-Ryan

 

[tbirdvet]

Mercruiser has made both designs. It is my understanding that on the larger higher HP engines they use the steel tube design. My research indicates the only issue of not having the original rubber tube is noise, no functional issue.

 

[roger275]

I found the tubes and best price was Iboats who sells a Sierra cross. MERCURY MARINE 78458A1 They say these work for Alpha and Bravo drives.

 

[SCORPIO]

Sounds like I could have used one of those last weekend. I had to replace the water supply hoses from my OD to the transom houseing due to kinks (I think thats what caused my low speed heating problem). In doing that, my port exhaust bellows came off at the OD. What a PIA that was to reattach without an expander and pulling the OD. My hands are still cut up. I almost just removed the thing but didn't want the noise.

 

[half_full]

The mercruiser manual I have states that the exhaust bellows restrict exhaust flow and can bulge causing the u-joint bellows to contact the u-joints. Thus wearing through the u-joint bellows. Right or wrong, that's what the manual says.

 

[CAGE RATTLER]

getting ready to install a new 2010 496 MAG and have been reading the installation manual and found this.........

496 MAG with Bravo Sterndrive Exhaust Recommendation
IMPORTANT: To get maximum performance from 496 MAG engines with Bravo sterndrives, through the transom
exhaust is required. It is recommended that the exhaust bellows on the transom assembly be removed. This is
necessary to avoid creating a vacuum at the exhaust outlet in the propeller at higher boat speeds. This vacuum
could degrade propeller performance on some boats.
NOTE: If noise regulations do not allow the use of through the transom exhaust, an Exhaust Pipe Kit (807130A20)
and intermediate elbow kit (44267A1) must be installed for through the prop exhaust. This kit also contains an exhaust tube that is used in place of the exhaust bellows.​

Is this something i need to be concearned about on a boat that will probably only top out at 40-45 MPH?
I have the exhaust bellows and was wondering if i should replace it with an exhaust tube.

 

[Jimmy Buoy]

Sounds like I could have used one of those last weekend. I had to replace the water supply hoses from my OD to the transom houseing due to kinks (I think thats what caused my low speed heating problem). In doing that, my port exhaust bellows came off at the OD. What a PIA that was to reattach without an expander and pulling the OD. My hands are still cut up. I almost just removed the thing but didn't want the noise.

Here's an easier way to reconnect the exhaust bellows using simple zip ties!