Exhaust Riser Doomed to Fail

[Steve]

Sirs,

From reading prior posts and articles, it looks like we have an exhaust riser that is “doomed to fail.” It’s the factory set up for our 2008 Back Cove 33 with QSB5.9 425hp. We have about 850 hours on it.

What are my options here? Can the elbow be rotated, is this a custom fab job or is there another possible solution?

(Sorry about the last photo, I couldn’t figure how to rotate it)

Thank You,
Steve

Topic

[Tony Athens]

#1—————–You need to start reading here and don’t stop until you “see” & understand what it means to inject water on the “down hill” run..

https://www.sbmar.com/category/articles/exhaust-systems/

#2————— Look at the picture attached and just ask yourself what happen when the internal thin wall of the mixer sitting in the orientation yours is in, will happen when it corrodes thru? Where do you think will the salt water go?

It’s not if it will fail, it’s when it fails.

As to the results?———The rest is history..

Tony

[Fireisland1]

Can I get a better explanation of the “doomed “ part. Is it because it is not supported or is there a design flaw? I ask because mine is similar

[Rob Schepis]

Steve,

Sounds good on the steering lines, it sounds like you’ve had a visual on them, just be sure to check close for any rub marks because what you see when all is static at the dock may not be 100% as to what is happening underway.. In many cases a ride in the engine room can reveal things you’d never see sitting at the dock.

I attach a link (and there are others if you search the sbmar website for “exhaust”) about designing the exhaust, esp. the risers. In your photo it looks as if you have some unused height in the engine room. The best custom design will use all of the height and will also come down on the angle to get the water away from the engine as fast as possible. No wet risers.

The “method” is to take a lot of pictures from all angles, and then from there your fabricator will understand the “obstacles” that become the guiding factors as to YOUR riser geometry requirements. A dimensional/elevation drawing is then generated to identify those critical distances. On the shop floor a mock engine room is setup to include those critical obstacles and dimensions.

To simply take your existing setup to a fabricator would leave much room for improvement.

Designing a Marine Exhaust System

[Tony Athens]

Yes, from what I can see the turbo looks good and your elbows are not leaking yet… But, please send those pics in HIGH res direct to me at:

[email protected]

Tony

[Philip]

I think you are a lucky dude as the turbo looks really good to me.

As for exhaust fabrication it’s a little more than take the old one in and have it redone. Your going to have to talk with Seaboard or a custom exhaust manufacturer directly. Basically you can do it with some careful measurements and pictures, maybe have to send the old one in as well or do a mock up using PVC, but any quality builder will walk you through it.

When you do it consider a separate post on how you measure it up, and what the before and after looks like when done.

Phil

[Steve]

Here is looking back up towards the elbow.

[Steve]

These are the best I could get of the turbo on the exhaust side. What do you think??

1 user thanked author for this post.

Corey Schmidt

[Steve]

Rob,

So assuming my turbo is unharmed….how do I get from here to there? Do I just remove the old elbow, take it to a fab shop and say I want the same thing but with the seawater connector on the downward side?

Re: the exhaust hose and steering lines. It’s deceiving from the picture but they are actually separated. Nothing has dripped out of the connection yet but I’ll make sure to snug it up and keep a close eye on it. Thanks for catching that.

I’ll get the turbo pictures posted in the next few days.

Thank you gentlemen,
Steve

[Rob Schepis]

You’ll be looking at something similar in design to the attached dry riser.

Noticed in your exhaust hose pic that the hose looks like it might be up against your steering lines at the AP pump. See my arrow. The exhaust hose will vibrate, etc. with the movement of the boat and the rush & weight of water running through it. It also looks like the fitting closest to the hose is showing some signs of leakage? that the others are not. Needs a close look and possible shifting of the pump slightly for ample clearance.

[Steve]

Roger that Corey. I’ll get the pictures posted later this week.

[Corey Schmidt]

Doomed…

Steve, this exhaust is SUPER doomed to fail… not IF —- WHEN.

Please pull the riser off and snap a few pics of the exhaust side of the turbo so we can assess whether or not any damage has been done as of yet.

Then we can go from there… only real way to fix this situation is to build a custom riser that suits the boat 100%… IMO worth every penny.

Corey

[Author]

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