Cracked Exhaust Elbow

[Brett I. Miller]

I was motoring out of the West River for a sunset sail last week and I started to smell something funny. I turned off the engine and opened the engine compartment. There was smoke and a fair bit of water in the engine compartment. I checked around - belts etc. -- and nothing obvious was amiss. Had someone crank the engine and raw water started to spurt from the exhuast elbow which, as I discovered, had completely cracked in half. The engine usually starts within seconds of turning the key, but on the second go, it did not. Sailed back to the slip -- not fun, but I'm well practiced at it after years of troubles with the prior engine. The oil looks fine.

The mechanic is coming next week, but in the meantime I'm concerned that something bad (i.e., costly) happened. Unless the engine aspirated some raw water exiting the elbow, I should be ok, right? I'm particularly concerned cuz I'm dealing with a newly installed 3JH4.

Am I missing something? Thanks for any insights.

Brett

[Al Levesque]

If the oil has any gray to it then the crack allowed cooling water into the engine. If the engine was hard starting that was another sign of possible water incursion. Sometimes a single change of oil and filter and much running at temp can clear the water. Some suggest multiple changes of oil. If the oil looks normal then something else caused the hard start.

[Boyd]

Hi Brett:

When the exhaust system breaks seawater often gets into the cylinders via the exhaust manifold. This causes the rings to contract and they usually stay contracted resulting in a loss of compression. One symptom of this is you get a lot of black/grey soot in the water when you try to start.

I had the same event and ended up pulling the head and doing a rebuild. Its an easy rebuild without removing the engine from the boat. Just hone the cylinders and put in new rings. I did the valves and a lot of other stuff while I was there due as a result of poor maintenance by the P.O.

One possible ray of hope is if you can get the engine started and fully warmed up, that MAY allow the rings to reseat. My mechanic squirted oil in the cylinders via the preheater holes, hand turned the engine, replaced the heaters, and then cranked it. This helps the rings seal and may result in an engine start. This proceedure has to be done very carefully as there is no headspace in a diesel. If done wrong it will cause the rods or crank to bend. Basically its like doing a compression check. It didnt work for me due to the bad valves.

I hope yours goes better.

Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.

[cguthrie]

Hi Brett, my exhaust elbow rusted and burst through too last week. The boat is on the hard awaiting repairs and I hope that the problem isn't more serious than just replacing the elbow. I've been told to insist on a brass elbow -- it should last longer. The mechanic at Robinhood seems to know what he's doing, however.
Good luck!
Cliff Guthrie

[Leo MacDonald]

Hi Cliff,
That would be BRONZE, brass will be eaten away by seawater.

[Steve Laume]

Okay guys, brass or bronze whatever, how do you deal with a cast iron mixing elbow? I was very surprised to find that my old exhaust riser was simply a few black iron pipe fittings. The new one I put in is the same thing. I have no idea how long these things last but it seems a poor choice of materials. I do not see how using more noble materials for the riser will help much when the mixing elbow is still cast iron. It might even cause additional problems for all I know. Maybe not, as there are other situations where there are brass or bronze fittings attached to the cast iron engine block. I still look at the exhaust system as a chain with the mixing elbow being cast iron, it would become the weakest link.

I really like the idea of a welded stainless steel riser and mixing elbow. If I had been aware of this option when I replaced mine I would have been making a trip to my welder guy. This was not a pleasant job. It would be nice to have a permeant solution.

Replacing the exhaust made an incredible difference in how my engine preformed. The old elbow was nearly carbon and rust blocked. This maybe a reason to replace the whole thing every so often. Any ideas on carbon build up in stainless systems?

I am so grateful I found my problem during the off season.

Get her done and get back out sailing, Steve.

[Brett I. Miller]

Thanks to everyone for the the responses and I'm sorry to hear that I'm not the only one to have experienced this problem.

I got the diagnosis this afternoon and, yes, I had water in the cylinders. The good news is that they got it in time and it does not appear that a major rebuild is going to be required. The oil looked fine b/c the water handn't made it to the pan yet. The mechanic was highly critical of the install of the exhaust system during the repower. As it turns out, the exhaust system was the only element of the initial repower that didn't have to be completely redone due to incompetence! I'd certainly rather be sailing than writing a nasty-gram (with a draft complaint attached), but the boat won't be ready for this long weekend, so it looks like I'm going to have some time on my hands. Repower = no fun.

Best,

Brett

[Bill Michne]

Sorry to hear all the tales of woe regarding exhaust risers and water backing up in to the cylinders. I had it happen...twice. Both times were directly attributed to the total incompetence of the installers. The first one required an engine rebuild, the second did not because I recognized the situation immediately, and got a mechanic to flush the engine right away. The final solution was to have a competent yard weld a new system out of stainless steel, and install it with the proper bracing. It has been in for three years now with no problems, and it still looks brand new. Not cheap, but having work done by any of the majority of yards, who hire high school dropouts for minimum wage and call them diesel mechanics, will cost far more in the long run. Caveat emptor.

[Parfait's Provider]

I have a new Yanmar mixing elbow for sale if anyone is interested. Email me if you'd like particulars. Price very negotiable.