Exhaust Bellow Purpose

[allinmygarage]

So I was replacing my impeller and I noticed my exhaust bellow was in horrible shape. So I decided to replace it. When I went to buy the new one at the marina the parts guys stated that the exhaust bellow doesn?t do anything other than keep the exhaust noise down. Is this true?

I have a 1990 Maxum I/O 4.3 Mercruiser with an Alpha 1 outdrive. It has the through prop style exhaust.

 

[nlain]

Re: Exhaust Bellow Purpose

It also keeps water out of your boat when at rest, if it starts leaking your boat will sink. You have 3 bellows in there, exhaust, shift, and driveshsaft, inspect and change as needed, helps keep the boat floating.

 

[allinmygarage]

Re: Exhaust Bellow Purpose

Ok I searched around more and found this previous thread on the topic as well. Sorry for starting a new one. :redface:

http://forums.iboats.com/showthread.php?t=390457

Looks like the parts guy was correct it will only make it louder and not impact anything. I did put the new one in but wanted to know anyway. I also did check the other 2 bellows and both looked new or in great shape.

 

[carcraze]

Re: Exhaust Bellow Purpose

As far as I know the exhaust bellows will not cause a boat to sink. The shift or ujoint bellows can though. It is just the path for exhaust and exit water to get to the drive and through. If the exhaust is in bad shape though I would think that could be an indicator the check the others.

 

[45Auto]

Re: Exhaust Bellow Purpose

It also keeps water out of your boat when at rest, if it starts leaking your boat will sink.

WARNING - THE ABOVE IS TOTALLY FALSE AND INCORRECT

The parts guy was correct. The exhaust bellows is open to the water through the prop at all times. If your prop is in the water, your exhaust bellows is full of water. All the exhaust bellow does is direct the exhaust gases through the prop. Take it completely off and your motor will be a little louder at idle and a lot louder on plane. Many of them come with small vent holes in them when new, and lots of people replace the bellows with an exhaust tube (easier to install) which is not even connected on the aft end.

 

[allinmygarage]

Re: Exhaust Bellow Purpose

Thanks 45Auto - I always like the reassurance. Plus to be honest with myself it was so difficult stretching it to get it on the other side I really dont trust that it will stay on anyway. I even used the adhesive crap. If it was the V8 I would welcome the extra noise Thanks again.