SO 42DS Yanmar exhaust mixing elbow

[Trevor]

When doing general checks after purchasing our SO 42DS I noticed some corrosion around the exhaust elbow and the evidence of a water leak that had caused corrosion below that point on the gearbox housing and engine mount.     The rest of the engine is perfect and this caused me some pain as I try to keep things as close to new as possible. The exhaust mixing elbow takes the cooling salt water and mixes it with the exhaust gases from the exhaust manifold. From there it goes to the muffler (housed in the port side engine mount housing) and off to the exhaust outlet on the port quarter. It is made out of stainless steel (316 I think).


I thought I would check out the cause of the problem which grew into quite a saga. Firstly the join between the exhaust mixing elbow and the manifold had signs of salt water leakage. When running the engine I noticed a VERY slight bubbling of water on the outside of the pipe to flange join. This was the reason for the corrosion. When the elbow was removed and cleaned up a very fine crack could be seen. You can see the crack in this photo.



I thought I would try to weld it and resolve the problem. The result is below. Not perfect but good enough and better then the original as I don't think this will develop any cracks



The elbow was put back in place and tested. After the job was finished I wondered why the manifold to elbow gasket had shown signs of corrosion and it occurred to me (as I was driving home believe it or not!!) that the inside of the elbow may have the same cracking as the outside of the elbow. Too late now as I had put the whole thing back together but it was worrying me.

In the meantime, the exhaust pipe to the water muffler had developed the classic Jeanneau 42DS fault as outlined in this thread. I had obviously disturbed it when doing the work on the mixing elbow.

jeanneau.proboards.com/thread/2721/jeanneau-so42ds-2008-water-bilge

As it was leaking quite badly, I had to remove the exhaust elbow again so I had another chance to look at the elbow and sure enough, when I looked it was cracked on the inside as well !!



Once again I took to it with my welder. Not that tidy but once again functional.



I tightened the flange into the muffler and reinstalled the Exhaust elbow.



These exhaust mixing elbows are supposed to be replaced alarmingly regularly. If they fail they can leak salt water on the outside but more importantly they can leak salt water to the inside of the exhaust manifold.

I am surprised that an exhaust manifold that is made out of stainless steel can fail with less than 500 hours of use. This is a trap we should all take pretty seriously. Apart from those hairline cracks the exhaust elbow looked almost brand new. No carbon build up and certainly no sign it needed replacing. I have heard you can purchase these as an after market part at a competitive price that is more robust than the original. I must confess I am not very impressed with the Yanmar original. I have not yet been able to locate a more robust replacement. Perhaps someone may know of them?

I should have replaced this elbow rather than muck around and fix it but it has bought me some time to locate a replacement and I learnt something by playing around with it! 

I hope this helps someone who may experience a similar problem.

Regards,

Trevor Bird

[Tafika II]

Hi Trevor!
Thanks for the thread. I checked my fitting and it is not leaking; however, there is a very bit of rust. I used a SS cleaner on it (Spotless Stainless...great stuff) to clean off the rust, then took some toolmaker's die to see if there were any cracks (outside)...None evident

I'll add this to my Inspections List. FYI, the replacement part for my Yanmar 4JH4AE SER# E06649 is the Mixing Elbow 129670-13580. If I do replace it and the old one is reworkable by re-welding it, I use it as a backup.

[Trevor]

Hi Tafika II,

The thing that surprised me was the seemingly great condition of the exhaust elbow and the extremely hairline cracks that had formed on the outside and the inside of the join. I had actually witnessed the slight water bubbling on the outside which really gave it away. When I took the elbow off the second time I plugged the water inlet and filled the elbow with water.   Sure enough I could see a very slight leak through the crack on the inside of the flange as the moisture was seeping through.   

I am surprised such a great looking part could have such a simple flaw requiring it to be replaced so regularly.   I think it is about $450 (Australian) so it is not particulalry cheap and according to the manual should be replaced every 500 hours or 2 years!

An aftermarket one that doesn't need to be replaced so regularly would get my business as that single point of weakness seems like bad design to me.

Regards,

Trevor

[gowell101]

I had the same problem with my 2005 SO40.3
Replaced the elbow and had the old one welded to keep as a spare.

Please check the hoses and clamps below the exhaust. 2 or 3 hoses, 25mm dia?
The rusty water dripping from the exhaust crack collects in the screw part of the hose clamps.

I had 2 clamps break, causing some flooding.

Make sure the screw part of the hose clamp is on the top of the hose, not underneath.


Now have several hose clamps in my spares kit, just in case.


William

[Mistroma]

I've had problems with water injection elbows on previous boats and decided to check the elbow on my 2009 42DS after a year. All seemed well but I did notice that the inner and outer tubes were made of different types of stainless. I think that the outer was magnetic (ferritic/martensitic) and the inner was not (Austenitic?). I assumed that this a deliberate choice by Yanmar. However, I've no idea if it was made that way to reduce corrosion problems.

I decided to try something to extend the life of the elbow after I discovered the price of a spare. Fortunately the elbow was still in excellent condition and only needed a quick clean to remove a little carbon and then to be left for a while to let the Chromium Oxide layer reform. I did note some minor pitting inside the inner tube before painting the inside surfaces. Unfortunately, I'm not in the UK just now and can't remember the name of the paint.

I don't know if it helped but take the elbow off each year to inspect and have cleaned & repainted once more. So that's 2 paint jobs since 2010 and no change in condition at start on 2013.

I still have the spare I bought but don't think it's likely to be needed for a few more years. If I do get 7-8+ years from the original then I think that I'll paint the inside of the replacement before it is installed. However, it would be interesting to hear if anyone thinks I'd get 8+ years without doing anything to the standard elbow.

[Tafika II]

I have triple clamps on the hose, but I think I will contact Yanmar directly (I know...good luck) as ask them what the material(s) are and if stainless why they would be rusting & cracking. Maybe they have a solution or a preventative solution for longer terms wear & tear on this pipe. I'll let you know what I find out.

8/22 - Sent email to Yanmar...waiting their reply

[MalcolmP]

Very useful thread indeed - made me give a careful check to the elbow on my 40hp Yanmar and there has been a slight drip - can't see yet if it is a crack or just a gasket leak - more worryingly is that the salt water has dripped on to the cable connectors which were located directly below the elbow . In the three photos below you can see the salt staining and also how I have now rerouted the loom so if I cant fix the drip at least it will not splash onto the wiring.  I plan to get a new elbow and gaskets fitted in next couple of weeks so if it shows any wear/crack in teh elbow I will then attach photos of the old elbow.

More worrying perhaps is that on our recent cruise the boat used about 200ml of coolant which it had not in the past - thought it might be down to an airlock - but this weekend the coolant level had fallen again - no signs of leakage anywhere , so presume must be through a gasket leak (maybe the head) but hope not....any thoughts?

[Tafika II]

Hi Malcolm,
The elbow and bleed off connector on my Yanmar corroded. The drain entire fitting connection where is was brazed onto the elbow pipe was cracked and leaking. FYI, I placed a plastic cover over the wire connectors. Too many possibilities to get water on them if there is a leak of any sort.
Sorry, I cannot comment on the coolant leak...so far none on my engine

UPDATE: I remember now that the drain connector attached to the elbow went 1st (See photo). I replaced it, but it continued to leak. I took it off and that when the elbow pipe, braised fitting and connect broke apart (picture attached). Just added this for interest only.









Attachment DeletedAttachment Deleted

[Trevor]

Hi Malcolm,

Don't you hate it when the salt water gets onto the engine and engine mounts and corrodes them?! Very difficult to restore things when they have been corroded by salt water and the original paint is gone. I think your elbow looks good on the outside but I would bet the inside has a very fine hairline crack that has allowed a small amount of salt water to leak out of the manifold gasket. I agree the exact location of the cable loom connectors is unfortunate being directly below the manifold to elbow join.

I have no clues on the coolant leaking. Haven't seen that on my engine.........yet.

Trevor

[j]

On the same topic... there was a bad batch of 3YM30 exhaust elbows, ours was replaced under warranty by the local yanmar dealer when they did the 50 hour service and noticed some very minor rust spots on the flange weld.

[MalcolmP]

Thanks for the replies, I spoke to my local service guy today who take the elbow off for me and inspect as I am not back to the boat for a while  - it is our Daughters wedding this weekend ;-)  He said he could probably weld it OK - he said the normal problem is due to impurities in the original weld. I also found that standard UK price inc VAT is £314 plus £24 for the gasket so nice piece of after-market sales

Agree hate seeing any staining - I do try to remember to give the engine and ancillaries an occasional spray with WD40 to minimise that. I think now that the cables are away from the drip area they should be Ok but I may look to see if I can put some cover over them anyway

He said the engine coolant might be down to several things - even the heat exchanger in the calorifier might have a leak , so maybe not as nasty as a head gasket with some luck

[dan]

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Brent I have the same problem with my drain off, exactly the same as your picture.
What did you do, replace the pipe and drain?
Has any one ever attempted to use this drain or can it be plugged off?

[Tafika II]

Hi Dan!
I replaced both the pipe and the drain (+bought a spare). I've never used the drain and I'm not really sure of it purpose. It looks as if it could be ignored and plugged...in my opinion.

[Mistroma]

Coolant leak:
Can you see any coolant underneath the engine?

I've had a slight leak from my 4JH4AE since new. The Jeanneau dealer gave a variety of reasons, but none were correct. I tracked the leak down at the start of my 2nd season with the boat. It was coming from the inside end of the alternator adjustment bracket. I removed the bolt and found that this bracket covers a hole leading to a waterway. I assume that's the case as coolant dribbles out when the bolt is removed.

I made up a thin gasket and also applied some gasket sealant. This seems to do the job for a whole season but needs to be replaced at end of season and again at the start because I remove the alternator belt prior to winter storage.

This seems like a particularly stupid design, unless my engine is missing some sort of seal. I always lose a tiny amount of coolant at end and start of season but nothing during the season once the gasket is sealed up.

[Tafika II]

Like all good things on a boat, they fail eventually. I noticed some rust on the mixing elbow again, but this time it's leaking, so I order a new one and will repair the old as a spare. FYI new one is Mixing Elbow 129670-13561 (was 129670-13560) and the gasket is 129472-18090.

[alex1949]

Hi folks,

What makes me wondering is Yanmar's  reaction to all those complains...................??

As an owner I would probably loose my temper and use some nasty words.

 

[captbillh]

I had the same style mixing elbow on a Beneteau 373 with a Yanmar 3JH4E. 5 years and 700 hrs a very small leak. Had it welded but the weld heat distorted the flange so it is a coffee table ordainment. The cost was USD $385. The weld material is the point of failure, it seems.

[Tafika II]

I spoke with Yanmar at two boat shows and also made a complaint. I got excuses and crickets. I'm going to try again! Also found a local guy who can make a fabricated new one for $215 delivered out of Schedule 40 304 stainless. He also willing to refurbish the old one as a backup.

Update 4/15 - Project done and no leaks. Refurbished old one as backup

[sleighride]

I have a 75HP 4JH3-TE on my DS43 which I have had now for over 12 years and I just replaced the mixing elbow this last fall after reading this thread. The engine had over 3,000 hours and the mixing elbow showed no rust or any corrosion or cracks. I used a new standard Yanmar replacement elbow which I ordered through the local Yanmar dealer in Astoria, Oregon. 

[Tafika II]

I sent an inquiry to Yanmar again, along with pictures of my failing elbow & a link to this site. Here is the reply I received from Michael Dollfus at tech support ([e-mail])...

"Thank you for your kind information. As previously mentioned, I have done some research regarding part# 129670-13560. Part# 129670-13560 was changed in 2008 to part# 129670-13561. The reason for the part change was as you mentioned, there were complaints about the mixing elbow leakage from the field/customers. After thorough examination of parts returned for inspection, cracks were found as well as corrosion on the flange of the mixing elbow. Part# 129670-13561 is expected to be more durable, however these parts are considered to be maintenance items that need to be checked regularly.
You would still need to follow the applicable maintenance information provided in your owners manual.

I find it odd they found a flaw in the old model & created a new model, but never let anyone know. Yanmar is offering no relief...we are on our own!!!

[so36idavid]

Apr 8, 2015 17:30:29 GMT Tafika II said:

I sent an inquiry to Yanmar again, along with pictures of my failing elbow & a link to this site. Here is the reply I received from Michael Dollfus at tech support ([e-mail])...

"Thank you for your kind information. As previously mentioned, I have done some research regarding part# 129670-13560. Part# 129670-13560 was changed in 2008 to part# 129670-13561. The reason for the part change was as you mentioned, there were complaints about the mixing elbow leakage from the field/customers. After thorough examination of parts returned for inspection, cracks were found as well as corrosion on the flange of the mixing elbow. Part# 129670-13561 is expected to be more durable, however these parts are considered to be maintenance items that need to be checked regularly.
You would still need to follow the applicable maintenance information provided in your owners manual.

I find it odd they found a flaw in the old model & created a new model, but never let anyone know. Yanmar is offering no relief...we are on our own!!!

Honestly I find this a relief. Like many of us I've had to replace the elbow only to be told by Yanmar that this is maintenance to be scheduled every two years. At least they've figured out that they had a problem and done something about it.

I'm not terribly concerned about not being notified. I don't know how Yanmar would find me to notify me anyway.