cooling system leak

[Larry in Maine]

I discovered a small leak in my cooling system. I am a novice, so I don't know that name of the part. I've attached two pictures. They need to be rotated. It started off as a pinhole but I cleaned it out and now it is about 1/8". Anyone have an idea about a repair?

Laurence Starr
Camden, ME

[msmith10]

I believe that's your muffler and if I'm correct, you should consider any repair to be temporary until you can replace it as you run the risk of pumping CO into your boat as well as a water leak.
I think I've seen one of those before but I don't think you'll find a new replacement and you may need some major design changes in your exhaust system to replace it with something new.
As far as a temporary fix goes, I'd probably use JB weld, or a higher temp epoxy, maybe over a coarse fiberglass cloth mesh but I wouldn't count on anything sticking or sealing very well or for very long.

[edwardc]

What you have looks like a jacketed mixing elbow. Hot exhaust flows through a large passage in the center. Raw water flows through the jacket surrounding this exhaust passage and is injected into the exhaust at the end, further cooling it. This wet exhaust mixture goes through a water lift muffler and then out the stern.

This elbow likely came from a small Diesel engine, and you’re unlikely to find a replacement. Better off to rebuild the exhaust using black iron or stainless pipe (but NOT galvanized!) and one of the water injection fittings our host sells.

[ndutton]

That style of exhaust elbow is readily available even on eBay but know that they have their problems. If considering Ed's advice (I recommend you do), we have tons of helpful information available. Just say the word.

[Cat271973]

Are there any resources for building your own? I need a new one as well and would like to review Ed’s suggestion.

[edwardc]

Are there any resources for building your own? I need a new one as well and would like to review Ed’s suggestion.

Sorry for the late reply. I was out for a 5 day trip on the Chesapeake

My boat originally came with a wholly inadequate exhaust system. The injection elbow had absolutely NO riser, and injected the water very close to the manifold. This can potentially allow splashing and water vapor (after shutdown) to find its way back into the manifold and cause sticky valves over time. A properly designed system has a riser and then injects the water at least 2 1/2" below the high point in the riser, the more the better. This serves two purposes. The first is to help prevent the aforementioned migration of moisture back into the manifold and exhaust valves, and the second is to provide a little more "buffer" volume to help stave off a back-flooding event by just a little more in the event of prolonged cranking with the water intake valve open. The riser, also known as the "hot section" gets VERY hot and requires wraping in some high-temp insulation.

I rebuilt my exhaust system from 1 1/4" stainless pipe and the water injection point and manifold flange sold here by our host. This system had a proper riser and an insulated hot-section, and injected the water well below the top of the riser. This was about 12 years ago. At the 11 year mark, the flange (the only mild steel part in the system) rotted out and had to be replaced. The stainless was still perfect, and I expect it to outlast me!

I documented the project in this Moyer-hosted photo album.

Here's a link for the water injection point,
the manifold flange,
the high-temp insulation wrap for the hot section,
and McMaster-Carr for the stainless pipe.