Does dry joint exhaust = no more catasrophic failures?

[mjfink]

I have a boat with a Merc 350 Mag (2006) that has dry joint exhaust on it. I've always (as long as I've been boating) heard horror stories about failed exhaust and then failed engines. This boat is run in salt, but is flushed and dry stored after each use. Because of the stories, I always wonder if I should pull off the manifolds (or just replace them) to fend off a possible water intrusion issue.

What I'm wondering, does a dry joint exhaust pretty much preclude a water intrusion issue? Of course, it can still fail, but it will fail in the water jacket (and just overheat the engine, nothing really broken)?

Thanks for the help, I feel like the stupid exhaust is a hand grenade with the pin pulled, and just wonder if that's the "old" story, and not something I need to worry about as much anymore.

 

[Don S]

Re: Does dry joint exhaust = no more catasrophic failures?

What I'm wondering, does a dry joint exhaust pretty much preclude a water intrusion issue? Of course, it can still fail, but it will fail in the water jacket (and just overheat the engine, nothing really broken)?

Correct, the reason for failure of the older style manifolds was that thin 1/4" wide gasket surface between the water and the exhaust. it would corrode away and that is where water got into the engine. With the dry joint, that problem is in the past. Now if the corrosion builds up, it starts overheating. That is usually a slow process, first you notice a 5-10? increase in temp, a few weeks later it may creap up another 5-10? . That's your warning you are going to need new manifolds and risers soon, assuming your raw water pump is doing it's job.

 

[mjfink]

Re: Does dry joint exhaust = no more catasrophic failures?

Really good to know, thanks Don! One less thing to cross of my "worry about it" list. Just watch the temp and make sure everything looks good externally on them sounds like a great plan to me!

Correct, the reason for failure of the older style manifolds was that thin 1/4" wide gasket surface between the water and the exhaust. it would corrode away and that is where water got into the engine. With the dry joint, that problem is in the past. Now if the corrosion builds up, it starts overheating. That is usually a slow process, first you notice a 5-10? increase in temp, a few weeks later it may creap up another 5-10? . That's your warning you are going to need new manifolds and risers soon, assuming your raw water pump is doing it's job.

 

[scoflaw]

Re: Does dry joint exhaust = no more catasrophic failures?

Will the manifold need to be replaced if it's closed cooling?

 

[Don S]

Re: Does dry joint exhaust = no more catasrophic failures?

They shouldn't.

 

[holmesSA]

While the gaskets may not fail... THE CAST IRON DRY JOINTS RISERS DO FAIL!!! There is still a thin wall of cast iron that deteriorates, and the surface exposed to saltwater cannot be seen even after removal. Below you can see the large hole in the riser where saltwater was entering the exhaust manifold and then my ENGINE! The engine temperature was perfect. The engine only had excessive fuel in exhaust, which I chased for several weeks. Thinking it was either a bad fuel regulator or the injectors.

This happened on a dry-joint exhaust system with coolant in the manifold and saltwater in the risers. Freshwater cooled with BLOCK-OFF gasket

Change your risers if you have not. Inspection may not be sufficient as it is impossible to see the saltwater side of the surface that is rotting away. CHEAP INSURANCE... compared to a new engine.

 

[Fun Times]

Sorry to hear of your potential damage to your engine holmesSA. due to this archived topic. Unfortunately all gaskets tend to fail over time eventually causing damage. Let's hope for the best in your case. Below is some info from forum member achris where he caught his early enough before severe damage occurred.

http://forums.iboats.com/forum/engi...tdrives/605286-dry-joint-elbow-gasket-failure

With the number of views this topic has, it's best to keep this post here vs starting a new one. That mentioned, lets let this one drop back down into the archives...Thanks everyone.

 

[Bondo]

This post may have cost me my engine. THESE RISER DO FAIL!!! As you can see the large hole in the riser where saltwater was entering the exhaust manifold and then the ENGINE!!!!

Ayuh,.... Welcome Aboard,..... Don S never said the Risers will never fail or cause problems,....

The only difference is the Gaskets,.....

Correct, the reason for failure of the older style manifolds was that thin 1/4" wide gasket surface between the water and the exhaust. it would corrode away and that is where water got into the engine. With the dry joint, that problem is in the past.

It appears you read what was never written,.....