Mysterious exhaust parts need to identify

[sanibel sailor]

My engine takes a 1-1/2” NPT threaded pipe for exhaust.
I put in a close SS nipple to replace the rusted steel original.
I had a welder make up a new spare elbow from a 45 degree stainless ell with a hole drilled in it and a 3/4” 90 degree hose barb elbow (I cut the other barb off) welded to shoot the cooling water downstream so it does not back up into the engine. A piece of TOE (threaded one end) pipe then accepts the rubber exhaust hose.
Sourced 316 SS parts off eBay and McMaster.com, local welder drilled and welded it together. Less than $100 all together.

[Carl-T705]

Originally Posted by skipperpete

You can do this[emoji844] either the full conversion to a complete wet exhaust or just the replacement of the outer hose on your current dry pipe installation.
No matter what road you take, the addition of a vent loop is imperative as you demonstrated when you opened the seacock with the outer sleeve of the heat rejection section open as in the early pics and water rushed in, this can’t happen with a loop and siphon break and a failure of the convoluted hose would be a non threatening event which would cause raw water to join the dry exhaust gas and exit via the large, above waterline exhaust outlet.
I’ve been close up with the convoluted SSteel flex a lot and its damned good stuff in 316, inconel or Monel and it can take 20 bar easily. It shouldnt be affected by plain raw water.
The end cap with the water inlet should unscrew to allow the replacement of the outer shabby hose.
I still maintain that this is a completely dry exhaust from engine to hull outlet and the section in your pics just ahead of the SS cylinder is the heat extraction part.
Good luck with the job.

DING DING DING.... we have a winner... in my opinion, There is no way in hell I would give up a dry exhaust for wet... Find a grey haired real mechanic and let him look at this system. Copper is good for about 25 years in this type of system, it's what Catalina used on their boats, but it was expensive, so that system got dump for a plastic waterlift system, what a shame

[Carl-T705]

Originally Posted by sanibel sailor

My engine takes a 1-1/2” NPT threaded pipe for exhaust.
I put in a close SS nipple to replace the rusted steel original.
I had a welder make up a new spare elbow from a 45 degree stainless ell with a hole drilled in it and a 3/4” 90 degree hose barb elbow (I cut the other barb off) welded to shoot the cooling water downstream so it does not back up into the engine. A piece of TOE (threaded one end) pipe then accepts the rubber exhaust hose.
Sourced 316 SS parts off eBay and McMaster.com, local welder drilled and welded it together. Less than $100 all together.

That's what I would call, quite the restriction in an exhaust system. If someone chooses to copy this design, I would increase the flow with a joint that is 1.5 on the engine side and 2 on the pipe side. The amount of drop and lift will determine if the water will back up into the engine. Nice work.

[dfelsent]

Originally Posted by skipperpete

I found a place in Gloucester Massachusetts that quite possibly made or supplied your existing exhaust systemAttachment 240630

I have not used Rose myself, but have been told they have a good reputation by a lifetime waterman.
They do a tremendous amount of commercial work.

[kenbo]

Originally Posted by sanibel sailor

My engine takes a 1-1/2” NPT threaded pipe for exhaust.
I put in a close SS nipple to replace the rusted steel original.
I had a welder make up a new spare elbow from a 45 degree stainless ell with a hole drilled in it and a 3/4” 90 degree hose barb elbow (I cut the other barb off) welded to shoot the cooling water downstream so it does not back up into the engine. A piece of TOE (threaded one end) pipe then accepts the rubber exhaust hose.
Sourced 316 SS parts off eBay and McMaster.com, local welder drilled and welded it together. Less than $100 all together.

If you have a 1.5" outlet on your exhaust manifold and that 45° elbow is 1.5" as well you've introduced significant backpressure to your exhaust system.

On edit, I didn't see Carl's post above. And 2" may not be enough depending on the run and how many elbows there are before the outlet. When I design exhaust systems I always measure the backpressure before it's put in service.

[kenbo]

To the OP, I have rebuilt a few very similar exhaust systems also on Allieds. How old is your boat, 40-45 years old and the exhaust system is still functioning...sort of. The leak you found is most like from chafe on the water jacket hose. Take the entire system out without cutting it and bring it to a reputable hydraulic hose outfit and ask them to replicate it. They probably won't have the 3" wet exhaust hose that serves as the annular cooling hose so you'll have to supply that to them. All in probably less than $500-$600.

You received good advice about adding a siphon break but I'd be surprised if there isn't one already fitted. Do that and you'll be good for another 40 years. Those original Allied exhausts are very well engineered.

PS get a different mechanic.

[Dave9111]

If that is truly a water jacketed dry exhaust system.

Fix it.

Don't replace it with a water lift. Water lifts are common because they are cheap and easy to install. They can also pump water into your engine if not done correctly. Almost no commercial boats use water lift exhausts. Take apart what you have and replace what is needed.

[Sailmonkey]

Originally Posted by Dave9111

If that is truly a water jacketed dry exhaust system.

Fix it.

Don't replace it with a water lift. Water lifts are common because they are cheap and easy to install. They can also pump water into your engine if not done correctly. Almost no commercial boats use water lift exhausts. Take apart what you have and replace what is needed.

And if the jacketed dry pipe fails the engine can drown as well. There’s no perfect system (unless you count North Sea stacks).

[kenbo]

Originally Posted by Sailmonkey

And if the jacketed dry pipe fails the engine can drown as well. There’s no perfect system (unless you count North Sea stacks).

Not necessarily, it depends on the install. If the dry exhaust is run downhill from the manifold or ideally after an inverted U bend to the transom there's no issue. These are a good design if installed properly (like all marine exhaust systems) and they create very little back pressure which all types of diesel engines prefer.

[Sailmonkey]

Originally Posted by kenbo

Not necessarily, it depends on the install. If the dry exhaust is run downhill from the manifold or ideally after an inverted U bend to the transom there's no issue. These are a good design if installed properly (like all marine exhaust systems) and they create very little back pressure which all types of diesel engines prefer.

The install that the OP has is not one of those failsafe systems

[john manning]

Your photos are not clear but it looks to me like a water jacketed muffler. I have built these for boat owners who requested them but never used them myself. They are of some use if the engine does not have a water jacketed exhaust manifold.

Do you need to replace it or just repair the exhaust inlet pipe attached to it.

[kenbo]

Originally Posted by Sailmonkey

The install that the OP has is not one of those failsafe systems

I tend to agree but the pictures leave something to be desired. But hey, that system has been in that boat for at least 40 years and the 4-107 is probably original and it looks like the hose is original too! Can't be too bad a design.

[kenbo]

Originally Posted by john manning

Your photos are not clear but it looks to me like a water jacketed muffler. I have built these for boat owners who requested them but never used them myself. They are of some use if the engine does not have a water jacketed exhaust manifold.

Do you need to replace it or just repair the exhaust inlet pipe attached to it.

The engine has a water-jacketed manifold. It's essentially a dry exhaust with a length of flexible SS exhaust hose jacketed with 3" wet exhaust hose that the manifold eject water flows through to cool the exhaust.

[taz2]

Thank you all for responding, a lot of great ideas along knowledgeable advice that I surely needed. I live close to Solomons, MD so I will need to look for a welder close to the island and home.

My Allied is a 1977, with many original parts, particularly the engine. I have had to replace, raw water and water circulating pumps, along withe impeller thus far.

Initially my head span around with all the responses involving different ways to tackle the problem.. I'm still debating the avenue to venture upon. I have researched all the 3 major parts needed if ($500) I replace the entire system. If I go down the road of getting some one to replicate the original say ($600) or go down the road of just replacing the hose ($500)/mechanic !

See the dilemma!!

Thanks everyone, I will keep you posted.