Exhaust Riser: quick fix and permanent fix options

[wyb2]

Today the galley smoke alarm went off while we were motoring the last mile to our anchorage. No burning smell, but a strong diesel exhaust smell in the cabin made it pretty obvious where to investigate. Sure enough, lots of black soot sneaking out between the layers of exhaust wrap on the exhaust riser. Peeling away the wrap revealed that the horizontal pipe of the riser had severed completely and now the exhaust wrap was the only thing holding the exhaust in. Judging by the amount of rust, I'm guessing the whole assembly was black iron plumbing pipe.

Just for clarity, this is a Universal M25 with the exhaust headers run through the coolant expansion tank, after the headers is the riser, which is about 18" long with a few 90 deg elbows in it, then the mixing elbow that drops into the aqua-lift muffler.

So the 1st thing I'm looking for is ideas/advice on how I can quick-fix this in a safe way. I've got something cobbled together right now using aluminum foil, the old exhaust wrap, and some high-temp tape, but who knows how long it will hold up, so I could be re-doing it very soon.

The 2nd thing is how can I complete a permanent fix, hopefully without being stuck somewhere for weeks waiting parts. I suppose re-doing it in black iron pipe and exhaust wrap should last another however long (5 yrs? 10?), but it seems like there should be a better way. Hopefully a way that doesn't involve that godawful wrap. I breathed in more fiberglass in the 15 minutes spent trying to get that wrap off than all the months of boatwork leading up to this trip.

[jimbunyard]

Well this is one option, 316 ss, copper pipe, bronze injection elbow...

[snotter]

I think you got the pictures of your homemade mixing elbow mixed up with the pictures of homemade still parts.

[DougR]

Quick fix is to go down to the Ace hardware store and get a handful of galvanized pipe and replace what you have with like....probably will last at least 10 years, probably much more. I did the same on my old 4-108 exhaust... It was 19 years old when it failed like yours, and the replacement was 15 years old and going strong when I repowered.

Or, fab a new one in stainless...

DougR

[Hoodsail]

If you can access it, refer to "Good Old Boat" magazine, Nov/Dec 2016 issue, in which author Robin Urquhart describes his DIY exhaust mixer, with a picture of the component parts, made out of parts available in most hardware or plumbing stores for his marinized, Kubota V1305 27-hp diesel..good luck.
dave

[Cheechako]

Many years ago I used galvanized pipe after the one on my MD2B Volvo failed . It was still good when I sold the boat.

[01kiwijohn]

Regular iron pipe will do the job. It has actually lasted you quite a long time already and other metals apart from a custom stainless job) won't give you much more. I was long ago instructed (not advised) to not use galvanised in diesel engine exhausts. I forget the reasoning but the engine exhaust system engineer who explained it had plenty of supportive data for it. I just did a repair on a Yanmar and, guess what, the mixing elbow is cast Iron, pretty much the same basic element as in your black iron pipe. It has lasted 15 years, in salt water.

[Stu Jackson]

You have a C36 with the same engine I do. I've replaced my riser two or three times in the past 20 years.

Try not to reinvent the wheel. There is a pretty good C36 forum at www.c36ia.org. They've discussed this endlessly. There are many options out there.

One trick I saw from a friend who replaced his A4 with an M25 on a Pearson 30, was to make the nipple for the raw water out of a galvanized T, using the top of the T with fittings to get down to a 5/8" hose barb for the water connection.

Muffler patch tape is a good interim solution.

Good luck.

[sailm8]

This might help

https://forums.sailboatowners.com/in.../#post-1432496

[jimbunyard]

Black iron or galvanized is of course quite sufficient. If you need the flange to screw your fittings into, add 100.00. Fittings from the hardware store are pretty expensive, but will certainly work. If you're trying to match up to your existing, built in muffler, you'll have to get some custom pipe cutting done.

Life will depend on usage-- 5-15 years? Price online for the materials illustrated were slightly cheaper than iron pipe including the Universal flange, but I have the ability to cut, weld and thread stainless. The copper pipe cuts down on heat in the 'engine room', and the high temperature of an insulated, steel pipe precisely where you don't want it, the bronze el prevents 'stainless rot' caused by injecting seawater into a hot, insulated stainless pipe.

Mainly it was just fun...

[jhulmer]

You can find additional good information in this thread:


http://www.cruisersforum.com/forums/...ml#post2578610

[georgeg305]

Westerbeke?Universal make a exhaust "heat riser" that bolts directly on to the exhaust manifold. Replaces all of the hot section exhaust pipe that the M-25 originally came with. I am having trouble posting a pic.

[Wotname]

Originally Posted by jimbunyard

Well this is one option, 316 ss, copper pipe, bronze injection elbow...

Just to clarify, what goes though the copper tube?
Nothing?
Forced air?
Engine coolant?
Raw water?

[iyamwhatiyam]

Hello wyb,

We picked up our '89 C-30 MKII (Universal M25XP) in Indiantown and motorsailed it to Jacksonville. Fortunately, we had good weather and all the ports and companionway were open as the exhaust was spewing upwards into the engine compartment without our knowledge. Burnt a nice 5 inch hole in the galley drawer above, (over time). If you saw it you would wonder why the boat didn't catch fire. Anyway, no one here needs a lecture about carbon monoxide. I ordered my riser from:

Len Keller
Catalina Yachts Parts Dept.
7200 Bryan Dairy Road
Largo, FL 33777
727-544-6681 x266
parts@catalinayachts.com
Open Mon.-Fri. 8AM-5PM

Here is the text:

John: This is the riser I inquired about a replacement for It measures 12" from center of pipe to center of mixing elbow The vertical pipe on the manifold side has a6" rise and the other side (mixing elbow) has a 5" drop into hose attached to muffler.
***
Hi John,

Please see photo attached. Center to center my riser is 12” long. Drop on hose side is 5-1/8 to 5-1/4”. The drop on the threaded side is 5”. Sells for $265 unwrapped, $350 wrapped in wire mesh, fiberglass padding and thermal tape. Threads are 1-1/2”NPT. To place an order please call me with your billing and shipping information.

Thank you,
Len

[jimbunyard]

Originally Posted by Wotname

Just to clarify, what goes though the copper tube?
Nothing?
Forced air?
Engine coolant?
Raw water?

Thought it was clear...raw water, you can put your hand on it under load.