Why marinize the exhaust manifold?

[Stu Jackson]

I'm confused by the OP. Universal 5411 - is this a raw water or freshwater (HX) cooled engine?

[captlloyd]

I ran a 5.9 Cummins turbo in my steel sailboat with dry-stack, dry manifold. No problems. I brought up pictures of your Z500 engine and it looks like you would have no problems wrapping your manifold. (Do the whole system.) Go to Summit Racing.com and you can buy the wrap. It might be a good idea to run a ventilation system to exhaust the hot air. I would put a thermometer in your engine enclosure and see what happens. I have had experience with Kabota engines, they seem to run pretty cool, especially the non-turbos. You might run your engine now in its present configuration and check engine enclosure temperatures. This will give you a measuring stick to compare your new system with. A remote engine enclosure temperature guage system would be very useful to monitor things.

[FamilyVan]

Poorly winterised wet exhaust.

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[brownoarsman]

Thanks for the continued thoughts. This is clearly a very high risk sort of thing, and I don't have the knowledge or skill of that boatbuilder to do the dry manifold bit right (though reading his article was a lot fun to see his workarounds) ... yet.
I'll check with the beta guys, that could work out really well so thanks for the tip! I'm also considering taking it down with a mill file to try and flatten the surfaces to achieve a less worrisome fit, or having an autoshop do it.

The hollowing out of the lower corner of the manifold is odd, it looks less like corrosion and more like water eating through sandstone - no rust or anything, just a carved channel. I meant to take a picture but had already fixed the gasket in place when I remembered. It looked like a previous owner might have tried to fill in some of the created gap with an epoxy like material. The owner directly ahead of me built a wall of high temp RTV over the water passage to try and contain it. Yes I realise this means I need a new manifold to go with my new water pump, as I know what Terra Nova's response will be! (Just kidding, I very much appreciate your advice and even took it on another thread about my cooling problem )

To clarify the engine, the 5411 is raw water cooled (no heat exchanger) and water will not enter the exhaust until the thermostat closes the recirculation line. I don't have the water passage picture in front of me, but it goes seacock, pump, block, manifold, thermostat, and then either into the recirculation line or into the elbow on the riser. There are multiple threads here and on other forums about 5411 owners in colder climates freaking out because they can't see water coming out with their exhaust as the engine would take so long to warm up that the thermostat wouldn't send water to the exhaust for a long time. I think this is probably part of the reason a former owner switched to the current ball valve, no thermostat arrangement. Instantly check the water flow. From the bits of burned out impeller I've flushed out, I'd even say it's very likely that's the reason!

Thanks everyone for continuing to put up with my questions and keeping me from endangering myself and others!


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[brownoarsman]

Just another clarification, the problem probably didn't originate with the manifold, but actually with the external flange for the riser. The vibration of the engine appears to have widened the bolt holes on the riser flange, which I imagine let the flange move around and unseat the gasket. Sign, new-to-you boats.


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[Terra Nova]

More likely escaping exhaust gas eroded it.

[brownoarsman]

I don't see how it could have been exhaust gas. The manifold has two openings, one for the exhaust, the other for the water passage (and it seems like a poor design to have this open and then be sealed by the gasket - what gives?
Again, wished I'd taken a picture as it would have made it clearer, but the area around the exhaust outlet is fine, it's just the lowest corner of the raw water outlet (which is very far removed from the exhaust outlet) which exhibits the wear. There is no channel or anything that has been formed by this towards the exhaust outlet, which is why I'm not overly concerned with the patch, as if the gasket fails, it appears that the consequence is a bit of a raw water leak onto the engine, not escaped exhaust gases or sea water entering the manifold.


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[Terra Nova]

Originally Posted by brownoarsman

...I'm not overly concerned with the patch...

[brownoarsman]

I know, I know TN, fix it the right way

Money and Time: two scarce resources!


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[SkiprJohn]

A job for Captain J. B. Weld.

[brownoarsman]

He is the best captain. Not too picky about berths, he sleeps in the nav table drawer. When awake, he commands the tiller pilot socket with quiet authority.

Are you suggesting that he also be used to fair the manifold? Unfortunately, he's overstepped his authority and under the orders of a previous owner, has taken command of one of my thermostat studs, resulting in a hump of epoxy around the stud that makes it very difficult to seal correctly!


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[Terra Nova]

Originally Posted by brownoarsman

I know, I know TN, fix it the right way

Money and Time: two scarce resources!...

Yeah, well...you have to start somewhere. And JBweld will only get you just so far. There is a difference between repair and band-aid. A band-aid is useful when you are temporarily away from resources but still need to make land, where you can affect a seaworthy repair. I think that is the focus that is sometimes missing, here, with the "that patch should hold for awhile" approach.

Think of the safety of your crew and guests.

[SkiprJohn]

Originally Posted by captlloyd

I ran a 5.9 Cummins turbo in my steel sailboat with dry-stack, dry manifold. No problems. I brought up pictures of your Z500 engine and it looks like you would have no problems wrapping your manifold. (Do the whole system.) Go to Summit Racing.com and you can buy the wrap. It might be a good idea to run a ventilation system to exhaust the hot air. I would put a thermometer in your engine enclosure and see what happens. I have had experience with Kabota engines, they seem to run pretty cool, especially the non-turbos. You might run your engine now in its present configuration and check engine enclosure temperatures. This will give you a measuring stick to compare your new system with. A remote engine enclosure temperature guage system would be very useful to monitor things.

Just curious but where did the exhaust exit the engineroom?

[Pauls]

I'd like to inject a little reality into this thread:
1. A dry exhaust is NOT hard to insulate. Diesel exhaust is typically not over 900 F. This is a low enough temperature that easily available insulating materials will work well. Go to www.mcmaster.com , they rate their insulations for working temp. Rock wool will work fine, as will some of the fiberglasses. Wrap the manifold and the pipe with at least 2" thick insulation. Cover that with an outer covering of your choice. Cloth saturated with silicone sealant works well, it is soft and flexible. Or you can use conventional lagging which sets up hard.
2. An exhaust system properly insulated gives off very little heat. You will find the outside of a system insulated as per above will be warm only. You can keep your hand on it. It won't heat up the boat much.
3. The exhaust does not have to exit up thru the deck. It can exit from the convential locations close to the waterline. This needs to be engineered for your hull material. With metal boats it is very easy to do.

It is possible to build a system which has significant reliability advantages over the conventional wet exhaust. And it can be done at a significant cost savings.

[Terra Nova]

Originally Posted by Pauls

...It is possible to build a system which has significant reliability advantages over the conventional wet exhaust. And it can be done at a significant cost savings.

While this may be possible, the real cost of such a system is often the smell and sound of diesel exhaust in your cockpit, plus living with a potentially serious fire hazard.