Exhaust Riser Relacement

[Captain Greg]

I am in the process of replacing the exhaust riser on the Universal M18 in our CD28. I would like to replace it with something more durable than the black iron originally used. I have found cast bronze elbows and was wondering how that would hold up. The only problem is that apparently there is no such thing as a bronze nipple; they are all either brass or red brass. Does anyone have any experience with with these materials in an exhaust application. Also, does anyone have experience with the universal riser sold by Westerbeke? It seems designed wrong. The water injection nipple is on the engine side of the riser.

[Boyd]

I suggest searching for an excellent posting by Zeida showing her new exhaust system for the Universal engine. She had some custom bronze pieces fabricated.

I am not sure what you are refering to by "Universal riser". I have a large aluminum casting which serves as the injection elbo on my Westerbeke. The water intake is low and next to the engine because it has an internal passage that cools the entire casting before the water mixes on the other side of the fitting.

Black iron is used for the hot part of the exhaust between the water cooled manifold and the injection elbo. It should be wrapped with several layers of fiberglass tape held on with hose clamps. This wrapping insulates the hot pipe so that it doesnt set the boat on fire. Black iron is used as opposed to galvanized because the galvanized pipe allegedly gives off toxic fumes when heated. Black iron should never be exposed to seawater as it will corrode out very rapidly. Being used in the hot section of the system it will last a long time.

Boyd
s/v Tern
CD30 MkII
Fort Lauderdale, Fla.

[Captain Greg]

Thanks Boyd, I will try to find Zeida's post. The Universal riser I was refering to, is something that Torrenson Marine has that Westerbeke apparently makes for Universal engines. It sounds like it might be similar to what you have. I am concerned though, because with the water injection nipple on the engine side of the riser and then introducing salt water into hot aluminum in an area where if it corrodes, the water has no where to go except into the engine. Is there a better way?

[Paul D.]

Greg,

I replaced my exhaust riser after it crumbled in my hands during winterization two years ago. I used heavy iron pipe and had a nipple or smaller tube welded into it at the same place as the old. I took it to my automobile repair place and they made me up a really nice one for $120. This included screwing it onto the original engine flange so it fit I bought some fiberglass tape and wrapped it up, installed it and it has worked well since.

I looked at Torrenson too but they are just too expensive for these types of parts. Perhaps my brother can chime in here with a few of the pictures he took of my assembly. It was for the Universal 30 circa 1982 5424 motor. There may be a post here with some pictures here is you search. I cannot remember.

Good luck,
Paul

[Bill Cochrane]

I've had the Westerbeke red cast injection elbow/riser for about 7 years or so...yes, it looks wrong but I was assured by a very good mechanic that it works fine. And it seems to be doing so.

<img width="540" src="http://i52.photobucket.com/albums/g37/w ... CN0689.jpg">

[Chris Reinke]

I had to replace my riser on a M30 about 5 years back while on a trip. A very highly recommended shop in Point Judith RI made up the riser out of cast stainless and told us that they used similar materials on the commercial fishing fleet based in Pt Judith. The cast stainless was the same dimensions as the blackpipe and threaded onto the existing exhaust flange without the need for any milling. We have not had any problems since the replacement.