Mixing Elbow: Hairline Crack - Can It Be Saved? (Doubt it)

[rardiH36]

A post for the forums diesel repair knowledgeable:

I've noticed a hairline crack on the mixing elbow of my 29 year old yanmar 2 banger. (A 2QM20 which is otherwise performing great!). A bit of salt water is oozing through -- just a few drops for the day's outing afterwhich I noticed it. Bound to get worse. And if water is getting through, probably undoubtedly some exhaust gas as well.

I expect that the general condition of the elbow is otherwise pretty bad and it can't be "reconditioned". And I am worried also that maybe the portion of the elbow that diverts the raw water from entering the exhaust manifold might be ready to go as well. But before talking with the local Yanmar dealer and ordering a replacement, just thought to ask for opinions of anyone who has encountered a hairline crack in this part --and the outcome.
Also I seem to remember from back in my DIY "keeping the old jaguar running" days, being told that spot welding cast iron, doesn't work very well. The adjacent cast iron is weakened by the welding heat so any weld repair fails in short order.

Thanks
rardi

 

[kloudie1]

You are correct.. Cast iron can be brazed, usually with widely varying results, but the ell is not that expensive .. Time to bite the bullet and get a new one.. The crack probably leads to a very corroded inside area..

 

[Rob19574]

Rardi - How old is the mixing elbow? it is one of the most abused pieces of metal with regard to the salt, heat and diesel exhaust chemicals so keep in mind that these types of parts don't last forever. You could probably get away with welding it and while its off check fro any internal leaks on the inner lining. For piece of mind and 5-10 years of not having to think about it - I would recomment replacing it if its 15+ yrs old.

You should also try to rig up a fresh-water flush on your engine so after your thru motering for the day, flush the salt water out of the block and exhaust system. I did this by installing a Y valve off my raw-water intake from my onboard fresh-water supply tank. Make sure the connections are secure and keep in mind that it is a below-water line system that could allow water back into the boat so think through the system carefully.

- Rob

 

[Stu Jackson]

Aw, shucks

Sorry to hear that, rardi. I understand that your elbow on your engine is different than ours, but the concept is the same. This is a picture of ours after it broke. I had tried the "Marine Tex on the outside hopin' it would keep it together" trick, but it didn't. It failed catastrophically a few months later. Thing is, they rot from the inside out, so what you're seeing is the LAST indication that it's gonna let go, no one knows how soon. I sailed back to my slip that day. Don't know what your dock arrangement is and given the winds some days whether you're in a position to do that.

 

[rardiH36]

Rob:

I'm the new owner of my boat/engine for only about 2-years now. So I don't know the history of the mixing elbow. Imagine the original elbow wouldn't have survived 29 years of salt water operation. But when the existing was replaced = "?"

Thanks for the idea about fresh water flushing. Makes good sense. Also I expect this greatly extend the life of the HX and HX zincs. However, being that the rest of the engine isn't a "spring chicken" anymore (nor the boat or me for that matter), installing a new elbow now, even for salt water operation, probably will outlast the rest of the components anyway. Also, I am sailing a few times a week mostly year round rather than extended times between use.

regards,
rardi

 

[rardiH36]

Re: Aw, shucks

Stu:

Wow! I do want to avoid a similar event. So I'm picking up the phone to List Marine as soon as I complete this post.

As a teenager, sailing my father's Lido 14, we became very good at kissing the dock under sail. But also the dock was oriented so that we could approach into the wind on most days. Now however:

- With a 13,500 lb boat,
- 10x's (or more) of that in $'s of fiberglass in neighboring slips,
- Mostly a cross wind at my slip, and often strong,
- Usually being the only able-bodied person on the boat,
- And at 58, a lot more cautious than would be a younger bloke;

I think that my first choice solution for the day the engine fails will be to dial up my towing insurance, then sail around in circles or drop anchor in Richardson's Bay until the tow arrives. Guess I'm a whimp at heart.

 

[sailingdog]

I'd point out that the exhaust system isn't one that you want to mickey mouse repair. While diesels generally produce a bit less CO than do gasoline engines... it isn't to say that they don't produce any... and exhaust getting into the interior of the boat is rarely a good thing.

 

[sailaway78]

Murphy's law of the sea

Murphy's law of the sea clearly states, the if any part is going to fail, it will be at the most inoportune time. Replace the elbow. Save yourself some grief at some time in the futre. Some parts can be fixed with JB weld, some with welding, some with duct tape. The exhaust elbow isn't one of these.

 

[Scott]

While I agree the best solution is to replace the elbow, in the interim, JB weld most likely work well. Many years ago , I fixed a crack on the exhaust manifold of a "68" GTO with excellent results.

 

[kloudie1]

Yup, Scott is riight, if ya need an interem solution, remove the ell and find the crack inside.. clean it up really well, then JB Weld the area up .. Brush to bright finish.. Do the same on the outside.. it will buy some time but if you can get the part fairly quickly, don't waste the time messing with the old one.

 

[Steve Dion]

Rardi: Personally I would just get the elbow and replace it. You are messing with carbon monoxide possibly entering the cabin (DEATH). These elbows are about $100 + gasket. You may need to take it to a shop and have them remove it from the manifold if you don't have some heavy duty equipment. They are usually all rusted together (manifold, coupling & elbow). Be sure to check the raw water elbow that screws into the mixing elbow too.

Goldenstate & KKMI should have this item in stock. Be sure to use some never seize on all the threads. It does not last for ever, but it may help the next time you try to take it apart.

 

[druid]

One thing: consider getting a custom-fabricated stainless-steel elbow made. It would be a bit lighter and last a lot longer, and you may be surprised how inexpensive it would be (take the old one to a shop and tell them what you want). I wouldn't be surprised if it's not much more than the cast-iron replacement.

druid

 

[petersea]

It is not a matter of IF it is going to fail completely but a matter of WHEN it is going to fail. As others have suggested possibly at the worst possible time. Change it out now and you got 7 to 10 years before you need to worry about it again. Doing a temporary fix should be an emergency only. If I recall parts (elbow and manifold exhaust parts, if you need both) are around two hundred dollars (don't forget new gasket and for another couple of dollars get new bolts) Trying to repair it and getting another year won't really save you any money in the long run and if you were to sell the boat a good surveyor would insist on it being replaced. You will surprised how quickly a "few drops" of salt water will start rusting any thing it drips on causing more problems. Fix it and forget it ! !

 

[petersea]

You are messing with carbon monoxide possibly entering the cabin (DEATH). quote]

Steve, diesel exhaust will not kill you, it will make you so sick you may wish you were dead but it is not deadly like exhaust from gasoline.

 

[Maine Sail]

Get a new one

You probably don't want to attempt a fix..

Here's why...

 

[Paul F]

Clogged Exhaust Mixing Elbow

Last Fall/Winter my mixing elbow clogged up with rust and stopped the engine from running. If your elbow is like mine - see attached drawings part #16. You can make up an exhaust elbow with galvanized pipe from a hardware store. The cost was about $25 for parts and $50 to have the starting pipe welded to the manifold. The old elbow was rusted to the manifold and could not be removed. It had to be cut off. The new pipe was fitted into the manifold and welded on. After that it is a matter of adding the right parts to mimic the old elbow - 45 degree bends, etc. Its not a hard project and when completed the next replacement is easy. [FONT=&quot]I can take a picture in a few days if you would like.[/FONT]

 

[Ken13559]

rardiH36, its either you " pay now or pain later ". either way you gonna pay. so better you get a new mixing elbow.

 

[Rob19574]

Guys - I heard if you are going to fabricate your own system you should use black pipe verses galvanized pipe. The galvanized coating bleeds off some nasty chemicals under the heat and stress of diesel exhaust. That type of set-up will also run very hot as its cant be jacketed with cooling water.

I just went through this for my Yanmar YSM12 - it cost about $320 for the entire system from the engine block to the muffler. Well worth the investment.

- Rob

 

[rardiH36]

Thanks -- And Comments

I'm always amazed at the enthusiastic and knowledgeable responses on this forum. A real resource for sure.

Rob: Yes part #16 is the part. I would be interested in a picture when you are able. Rob how was the elbow cut off from the manifold flange without damaging it?

This time around I will replace with stock rather than have a substitute fabricated. I'll save the removed one for in the future when I begin considering a new elblow again. That can be used for the fabrication template.

I'm still checking, but I've been quoted so far $170 (available locally) and $200 (+ shipping) for the elbow only. Not yet sure how rusted the threads are to the flange (looks clean from the outside) and what other parts might be needed. Strangely 1.5 years ago, after reading on this site about elbow carbon clogging, I did inquire locally about a replacement for the eventual day I needed one. I remember being told about $135. I am mystified why in this economy prices of so many things seem to be going up.

Again thanks ...

 

[NYSail]

Replace it...the inside is more than likely shot and the things that can happen if it completely fails will cost much more time and MONEY. When I bought my 1986 P36-2 my mixing elbow glowed on the sea trial and the engine overheated. The outside was paper thin and the inside was over 50% blocked