Exhaust elbow checks - 3YM30

[bdh198]

Hi

We have a Yanmar 3YM30 and I have recently been doing the annual checks. However, I have read recently that the exhaust elbow can be a cause of problems on this engine and that a close eye should be kept on it. In particular, they are prone to cracking and blocking.

I have never taken this part of the engine off before and just wanted to get some advice that this is something that can be easily done. I don't want to run the risk of breaking something that looks like it is working working. I have no reason to suspect it is not working properly, but after 7 years of owning the engine since new, and from what I have read, we should probably take it off and just check it.

Is there anything that I should be aware of before attempting to take this off? And once it is off is there anything in particular we should be looking for?

Thank you for any advice or suggestions.

 

[Cloven]

This should be an annual service check item. The following should tell you all you kneed to know

http://www.ybw.com/forums/showthread.php?420187-yanmar-exhaust-elbow-beware


http://www.ybw.com/forums/showthread.php?421692-3YM30-exhaust-elbow-gasket

3 YM & 2/3GM use the same exhaust elbow

 

[Cloven]

I have never taken this part of the engine off before and just wanted to get some advice that this is something that can be easily done.

Is there anything that I should be aware of before attempting to take this off? And once it is off is there anything in particular we should be looking for?.

Couple more specific comments.

Elbow is held on with 3 or 4 bolts depending on model. Easy to remove. You will then have to release the elbow from the flexible exhaust pipe. My be less easy to do if the pipe has become "work hardened". First time I removed mine I had to cut the flexible pipe off and replace it, fortunately only about 50cms to the water trap.

Once off, if it is in a bad way that may be immediately obvious by any cracks or weeping of the welds. Check how much carbon crud is on the inside and scrape it all out. I use a long screwdriver. Only once it is out will you be able to see whether the inner tube is perforated. Again, first time mine came off it looked fine but once the carbon was off, the inner tube was like a sieve.

Before you start, make sure you at least have a spare gasket to hand as the old one will be destroyed in removing the elbow.I carry a spare elbow and at least 2 spare gaskets on the boat.

Hope this helps.

 

[westhinder]

This should be an annual service check item. The following should tell you all you kneed to know

http://www.ybw.com/forums/showthread.php?420187-yanmar-exhaust-elbow-beware


http://www.ybw.com/forums/showthread.php?421692-3YM30-exhaust-elbow-gasket

3 YM & 2/3GM use the same exhaust elbow

Dave, does your advice extend to all Yanmar engines or just the 3YM or 3GM series?
I have a 3JH3 engine, the exhaust elbow of which has not been checked since I bought the boat nearly 5 years ago. I have not had any reason to suspect the elbow, the engine runs like the proverbial sewing machine, temperature and exhaust flow remain normal.

 

[charles_reed]

I too carry a spare elbow and gasket.
The 3YM maintenance schedule recommends cleaning at 1000 hour intervals.
Mine has gone 2186 hours with no apparent ill effects.
Call it infirmity of purpose - but taking it off and cleaning is one of those tasks oft deferred. Not something I'd undertake lightly as a weekend job.

 

[Cloven]

Dave, does your advice extend to all Yanmar engines or just the 3YM or 3GM series?
I have a 3JH3 engine, the exhaust elbow of which has not been checked since I bought the boat nearly 5 years ago. I have not had any reason to suspect the elbow, the engine runs like the proverbial sewing machine, temperature and exhaust flow remain normal.

I have no direct experience of your engine but I would say that it is very common for there to be no external evidence of the failure of the internal pipe on these elbows. I have had a quick look at the elbow for your engine and it appears to have the same basic design as that for the GM/YM series although it may be made of a different material. Whether this is more resistant to intenal corrosion I can't comment. However, I would guess that it will not significantly reduce the possibility of carbon build up which really needs to be cleaned out at regular intervals.

Sorry I can't give a more specific response.

 

[Cloven]

I too carry a spare elbow and gasket.
The 3YM maintenance schedule recommends cleaning at 1000 hour intervals.
Mine has gone 2186 hours with no apparent ill effects.
Call it infirmity of purpose - but taking it off and cleaning is one of those tasks oft deferred. Not something I'd undertake lightly as a weekend job.

In principle I would agree if this is something you haven't done before, particularly if you do not have all the possible replacement parts to hand - spare elbow, gasket and possibly exhaust hose. Its a job I do at the start or end of the season when I have no pressure to go sailing. However, once you are used to doing the job, assuming its just a removal, check, clean out and replace, it should't take more than a couple of hours at most.

 

[KAM]

I just took the elbow off my 3YM30 yesterday. It's only a 5 minute job. A 13mm socket to remove the 4 nuts and screwdriver for the two hose clips. One of the nuts needs a short extension but is all easily accessible. It came away from the soft gasket easily without damaging the gasket. After 700 hours there was just a small amount of carbon which came off easily with a damp pan scrubber.