While motoring the mixing elbow blew off the our 3ym30 engine with a loud pop and a hissing woosh. Must have had some pressure behind it when it went. We have a replacment and I'm in the process at this time but have a question. What kind of thread sealent ,if any, do you use?
Mixing Elbow
- Thread starter dfast7181
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I prefer Never-Seez as recommended by our Yanmar certified mechanic. You may want to contact your local Yanmar dealer and see if they have any specific product that they would recommend.
A tube or can may last a lifetime!
A tube or can may last a lifetime!
I am curious, did you have any symptoms before it happened such as sluggish power response, or smoking?
Was it plugged with carbon or scale?
Do you run the engine mostly at low power?
Didn't notice anything before the elbow came off. Engine seemed to be running normal. After some investigation I have answered a few questions about what happened. It appears that the threaded coupler that connects the ehaust elbow to the mixing elbow had corroded and that's what let go first. The ehaust was then being sent into the engine compartment which raised the temprature enough to set off the automatic fire extingushier, that was the wooshing sound I heard. After the elbow was replaced the engine would not start due to the automatic shutdown connected to the fire extinguisher.
The inside of the elbow was carboned up quite a bit but I'm not sure if was enough to cause problems at this time if the coupler had not corroded. One other thing about the exhaust elbow, it appears to be a Hunter custom made part for the 3YM30 on the 33. The Yanmar part is nothing like the one on the engine, it's much longer and would stick into the aft cabin if used. It looks like Hunter took a street-el, cut the threads off, and had it welded to the plate that attaches it to the engine. None of the parts houses have anything like it.
As to how the engine is run, we have about a half hour of run time, in a no wake zone, to get out of the channel so the engine is run at 1500 to 2000 rpm for that time. Then it's about ten minutes at 2800 to 3000 rpm until I get far enough out to put up the sails. The reverse on the way home. On the day in question we had 15 knots of wind on the nose and so had run at 2800 rpm for about 2.5 hours before the breakdown.
The inside of the elbow was carboned up quite a bit but I'm not sure if was enough to cause problems at this time if the coupler had not corroded. One other thing about the exhaust elbow, it appears to be a Hunter custom made part for the 3YM30 on the 33. The Yanmar part is nothing like the one on the engine, it's much longer and would stick into the aft cabin if used. It looks like Hunter took a street-el, cut the threads off, and had it welded to the plate that attaches it to the engine. None of the parts houses have anything like it.
As to how the engine is run, we have about a half hour of run time, in a no wake zone, to get out of the channel so the engine is run at 1500 to 2000 rpm for that time. Then it's about ten minutes at 2800 to 3000 rpm until I get far enough out to put up the sails. The reverse on the way home. On the day in question we had 15 knots of wind on the nose and so had run at 2800 rpm for about 2.5 hours before the breakdown.
Just heard from Eddie at Hunter Marine about the exhaust elbow being a custom part. I'm passing the info along incase any of you have need of it.
From the records this appears to be supplied with the engine from Mastry Engine @ 800-545-4574 or 727-522-9471.
Don
From the records this appears to be supplied with the engine from Mastry Engine @ 800-545-4574 or 727-522-9471.
Don
What year is your H33? My '94 33.5 has a standard Yanmar exhaust elbow, verified as I have a replacement on board awaiting time for the R/R. The existing installed part has a pin hole on one side with a rust stain running down from that location.
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