Soot exhaust leak

You could get a point and shoot thermometer. Set a base line, compare P and SB. Check them once in a while at similar operating temps. If it starts getting hot around the edges of the insulation or develops (much) hotter spots you can assume something's going on in there....

Was working on my Yacht today ...40 year old Ocean Yachts that is .
Took the semi-soot stained blanket off my Dawg and was able to pull off chunks of old iron from the bottom of the original J&T cast below at the round flange connection to the Turbo exit side .

Do you think it's time I change it out ?! 40 year old elbow.
Yes I did the starboard side three years ago.
My boat is a restoration in use vessel. Keep on using it and replace things as I go along. I love it

Thanks. Will do. I used to casually inspect the systems. I will now examine them more closely. Thanks Dan for raising the issue.

Yes, replace. If you're getting soot on the blanket you have an exhaust leak. If chunks of old iron are falling out of the cast elbow, it's shot.

They are stainless and I see nothing evidence a leak.

These guys make a replacement in cast stainless steel elbow that looks much superior to the original cast iron or a welded stainless mixing elbow and very inexpensive compared to the competition. https://hdimarine.net/

On their opening page they are showing bronze elbows for a SS mixer, Is that good? Mine are all SS, if my memory is correct.

I'm not the expert there but it comes with a real thick gasket and I don't think that joint is wet except when running. I do share your concern and wonder why that part is not stainless. Probably worth asking their opinion and others on yachtforums will likely offer advice.

good to know

What's a dump can? Other than the one we all already know about....
What's it purpose such as inline DD71s? and others?

Far from an expert my understanding is that the main function of the dump can is to cool the exhaust gasses so they can pass through the fiberglass tubing and “rubber” hoses as the exhaust exits the boat. I replaced mine as the yard was in there doing major work and the yard said the spray ring holes were becoming corroded. They said I had about 5 more years but I replaced them since access was available. I never saw any evidence of soot on mine.

Ok , so all combustion gas is passed through the turbo and out the elbow? With the elbow being water jacketed with a ring collar with holes in it spraying at the exhaust gas after the turbo within the elbow... ? This is where all the the cooling water comes from out the stern exhaust pipe ? The only source of water out the exhaust pipe ?

I do know if the elbow cooling water holes get clogged up you can have a big problem and or fire from all the heat generated there.

Check out the website at post # 29 for a visual of a replacement set up?