Cobra Exhaust Bellows

[RedRangerVIP]

OK,<br />according to a search , it is ok for there to be holes in the bottom of the new exhaust bellows that I got with a kit for my buddies' 1989 5.0 Cobra drive.<br />This seems strange to me !<br />Can someone tell me when and why they started doing this?<br />Thanks

 

[Boatin Bob]

Re: Cobra Exhaust Bellows

Yep...it's normal, they are more like slits that open up more as the drive is trimed up. I think it's supposed to help relieve back pressure at idle and make it run smoother.

 

[HT32BSX115]

Re: Cobra Exhaust Bellows

Yes, <br /><br />I was surprised that it had slits too.<br /><br />When I got this boat(87 FourWinns 340hp OMC) from my brother he told me all about having the exhaust diverters installed and how much quieter it is now when you select thru-the-prop exhaust!<br /><br />I noticed that the installer never installed an exhaust bellows on it and never removed the little plastic grill that goes in it's place on the drive side.<br /><br />He'd been running the boat with no exhaust bellows <br />for maybe 8 years!<br /><br />(he said that he'd always wondered why there was always exhaust bubbles etc right under the transom when idling around!)<br /><br /><br />I bought a new kit from Ebasic power and the new exhaust bellows had the slits.<br /><br />My old Mercruiser didn't have these of course.<br /><br />I'm sure they don't hurt anything. (Running without the bellows didn't seem hurt anything either!!)<br /><br /><br />Regards, <br /><br />Rick

 

[seahorse5]

Re: Cobra Exhaust Bellows

The main reason for the slits in the exhaust bellows is to keep the backpressure from "ballooning" the bellows on hard acceleration, especially on a large or underpowered boat. IF that happens, the expanded exhaust bellows pushes against the u-joint bellows, which in turn will contact the spinning u-joints and shaft. A few times doing that will wear thru the u-joint bellows very quickly and allow water in. That's not a good thing!

 

[RedRangerVIP]

Re: Cobra Exhaust Bellows

Thanks for all the info! <br />Just wanted to make sure before I install. Think I'll change out mine too!