Leaks: exhaust tube, muffler

[dee.yeah]

I've posted it on Engine forum, let me cross post here too.

My Yanmar 2YM15 is only 3years old on my Yamaha 25II. Lately I found there is a minor leak at the welding area of exhaust tube (where exhaust and sea water come out from the engine). Should I replace it or repair by welding? I'm a bit surprised of the leak on such a new engine. Is it common at all?

The stainless steel muffler has been leaking for quite some time. I've tried repairing it by re-doing all the welding. It appeared good for a month or so, but now it starts leaking again from needle-like tiny holes. It's been annoying, and I'm thinking to remove it and simply replace by a steel tube.

Also, the height of the muffler is not much lower than the engine exhaust tube. I'm wondering if it also causes problem.

Suggestions are all welcome! Thanks!

 

[Boffin]

better replace by a stainless steel one . There is a Australia supplier for this .

 

[Boffin]

This is from UK ,
http://www.boatpartsandspares.co.uk/yanmar-exhaust-mixer-elbow-1gm10-2gm20-707-p.asp

 

[Boffin]

other supplier

http://exhaustelbow.com/

 

[dee.yeah]

Thx Boffin. Will contact the supplier for the part.

Having read info on Internet, learned that exhaust system can be big problem if not installed properly or well maintaned.

So is the mixing elbow a consumerable part? And I read something about the exhaust riser. Is the big loop of the exhaust tube hanging at the transome(inside) serving that purpose?

 

[Boffin]

Pl share you experience on the order . I should need one in the future, as this is a consumerable parts , corrosive in the mixing elbow is common.

The problem in this boat is the engine being fixed in the front and at a pretty low profile . The water line is very close to the exhaust value level . when the boat rocking up and down , the water inside the exhaust hose will flow back to the engine when the engine is not working . So some use a exhaust riser to prevent the flow back water when the engine is not running . In my old engine , I got the mixing elbow raised some 2 inch to stop the water flow back . Check the level of the exhaust opening , if it is some 100mm above the water line would be ok. The installation of a muffer will reduce the effect also . Good luck!

 

[dee.yeah]

Thanks Boffin again for the info.

The exhaust opening at the transome should be high enough, if you are talking about 100mm. Also the big loop of the rubber tube hung inside the transome should also prevent the water flow back problem.

Anyway, I will replace the mixing elbow, and probably repair the muffler too.

 

[dee.yeah]

I had the muffler removed. With detailed check, the leaks are from corrosion on new welding area on top of the old leaks. I was thinking if it is caused by there is always residual sea water inside the muffler, as it is installed "leaning" certain angle. Any idea?

As the mixing elbow, the one came with the engine is made of steel already. I have sent it for re-weld, and will see if it lasts another couple of years.