I have a 2005 50 sedan bridge with...

[John_Keener]

I have a 2005 50 sedan bridge with 660 Cummins . The exhaust pipe melted to the point of almost sinking the boat-see pic attached. Has anyone else experienced this issue? I am told that it is a mixing valve problem 

[Gimme_Time]

Please continue to update this post with whatever information you find out as there a lot of these boat out there that will want to follow this thread.

[Captain_Rusty_H]

Afternoon John,....I am curious as well to your exhaust failure. Can you email me at [email protected] and let's talk about the cause related affects. Thanks!
Rusty

[Christina_Mari1]

If it has Cummins QSM11 the exhaust manifolds are dry and do not have cooling jackets. At approximately 1,000 hrs the manifolds can warp and need replaced. The heat discharged to the engine compartment can melt / burn many of the plastic components. I just had my port exhaust manifolds replaced, the starboard were replaced 20 hrs ago...

[Christina_Mari1]

https://www.sbmar.com/articles/propping-cummins-qsm11-to-prevent-exhaust-leaks/

[John_Keener]

Thanks Christina for the article. The engines are right at 1000 hours

[Captain_Rick1]

Your problem has nothing to do with a mixing valve. It's pure loading on the engines. Reduce propeller pitch and the loading decreases. IMO all diesel owners should go to Tony Akins for advice - no where else!

[John_Keener]

How do I get in touch with Tony?

[Christina_Mari1]

John, one other thing to consider replacing is the air filters. Because the soot is discharged into the bilge, it contaminates the filter to the point that you may notice the collapse of the element itself. Walker Engineering makes a filter that is about half the cost of Cummins. Mine was a WAE 90-132. Your parte number may be different.

[Captain_Rick1]

Tony Adkins owns Seaboard Marine. Contact him via the forum at
sbmar.com So much of the diesel advice on this site is hearsay with very little in depth technical expertise IMO.

[Captain_Rick1]

CUMMINS QSM11s come standard with Walker AIRSEPS. This problem has nothing to do with filters.

[Christina_Mari1]

John, air filters that have been exposed to combusted diesel fuel can look like this. This is the result of a leaking exhaust manifold, not the cause. I am certain a good local Diesel mechanic which has knowledge of Cummins should be able to help you out. I personally find any input valuable from someone else's experiences. That is why I am here.