Broken exhaust

[Cowpokee]

I recently had the mishap of my exhaust system coming appart.
Part of the threads from the part on the right are still inside the part on the left. It looks like a regular run of the mill closed nipple between the two pieces. Can I just go down to the local hardware store and get a replacement? Should it be black pipe, galvanized, or would stainless be better?

 

[NYSail]

I would just call your local yanmar parts dealer, order both parts and replace....

 

[31seahorse]

Hello Cowpokee,

Before repair you might consider answering a few questions (at least for your own enlightenment if not to be shared with us): First, what is the age and manufacturer of your engine? Second, are new replacement parts available? Third, are those new parts priced at a cost you are comfortable with spending?

The part on the right of your picture is the mixing elbow in which water and the hot exhaust are mixed just after the exhaust leaves the engine. There appears to be a crack in that mixing elbow and you mentioned that part of the threads are in the other exhaust piece. The interior surface of the exhaust manifold is thickly coated by carbon deposit. The inside of the mixing elbow is probably in a similar condition.

If parts are available I would choose to buy new parts plus any gasket that might fit on the flat surface. Since you already have the parts off the engine it would seem reasonably easy to replace them.

Afterthought: Can we feel confident that your boat is out of the water? I can believe that those parts are above the water line, but now might be a fine time to remove and inspect the rest of the exhaust system and replace tubing and clamps and perhaps the exhaust port through the hull if the boat is out of the water.

 

[Calif. Ted]

The Yanmar original part is stainless and the threads are reversed, one end left handed, one right. Probably most prudent to change all three pieces if you are unsure of it's age, Yanmar recommends inspecting every 250 hrs. and replacing every 500. About $350 for all 3 pieces and paper gasket from Yanmar dealer if my memory is correct.
There are after market elbows available, try E-bay.

 

[Calif. Ted]

That's a Yanmar exhaust elbow, probably 2gm20 or 3gm30, but used on MANY of their engines.

 

[Cowpokee]

Yes it is a Yanmar 2GM20. The boat is a 1983 and I believe it is the original engine. No idea on the number of hours.
Seahorse, good catch on the crack in the mixing elbow. The boat is still in the water but I did check, and I ensured the end of the water hose is well above the water line.
Great advice from all, I am glad I asked, I will replace all parts with new.

 

[Allan12210]

The part that bolts to the engine doesn't look too bad. Mine did the same exact thing as yours and I was able to work that broken piece out of it with a small chisel. I just tapped around and around until it collapsed into the center. That side is the right handed thread. In my case I was en-route to Monterey when mine snapped and I made an emergency quick fix to continue our trip. Later I replaced the threaded joint and elbow. I bagged my plumbing creation and keep it as a spare. The plumbing is standard 1 1/2 inch.

I just serviced my manifold. I swapped two of the bolts for 8 mm studs. It made it so much easier to pre-hang the gasket and the manifold rather than trying to line up a bolt, gasket and find the hole in the block. Then you just use nuts on the studs to finish the assembly.

 

[kloudie1]

Nice save, Allan..
Cowpoke, the part that bolts to the engine looks fine, extract the piece of broken nipple (right hand threads as Allan says) and re-ue it .. The nipple (connector) is left threaded where it screws into the mixing elbow and right threaded where it screws into the manifold piece.. That is Yanmar part # 104214-13580, about $34.. The mixing elbow is originally cast iron, Yanmar part # 124070-13520. The mixing elbow is available in original cast iron from Yanmar, or over the internet from some suppliers in cast stainless for a few less dollars.. The gasket is Yanmar part # 124000-13201 about $6.. The gasket is a high heat gasket, originally of asbestos now made of reinforced graphite..
I can't tell if the mixing elbow is cracked or just badly scratched across the top.. seems that if it were cracked, there would be a lot of rust staining there since that part has water behind the area in question..

 

[Richard19068]

Nice save, Allan..
Cowpoke, the part that bolts to the engine looks fine, .

In an expanded view doesn't it looked very coked up and restricted?

 

[Cowpokee]

In an expanded view doesn't it looked very coked up and restricted?

After a little cleaning, it was revealed to just be an area that the gasket didn't cover.

 

[Justin_NSA]

If it will help, you can have my elbow and threaded 'coupling' for what is would cost to ship it. I replaced mine with stainless but it doesn't look like it needed replacement. Mine is a freshwater boat. PM me and i can send you pics.

 

[Charles Erwin]

Justin. If it won't help here it could help me

Charles

 

[Cowpokee]

If it will help, you can have my elbow and threaded 'coupling' for what is would cost to ship it. I replaced mine with stainless but it doesn't look like it needed replacement. Mine is a freshwater boat. PM me and i can send you pics.

Thanks Justin,
Let me attempt to work on mine this evening. I'll get back to you with how well I fare.

 

[Justin_NSA]

You guys decide. I hate to see a good part go to waste. I can't imagine I'll ever need it.

 

[Cowpokee]

You guys decide. I hate to see a good part go to waste. I can't imagine I'll ever need it.

I managed to extract the piece of broken nipple from my elbow without tearing it up too much so it should be fine when it all goes back together. Go ahead and send yours over to Charles.