More Maintenance - Exhaust Elbows

Our engine is a Yanmar 3GM30F. The exhaust mixing elbow is a known wear item. It carbons up, and rusts out from the inside. While carbon can be scraped out, the internal rusting can't be fixed. It should be replaced regularly - especially if you are heading out for areas of the world where parts are harder to get.  Our engine is about 15 years old. The previous owner put about 550 hours on it over 10 years, and we now have a total of 2200 hours on the engine.  In diesel terms, it's fairly young - and I wouldn't be surprised if the exhaust mixing elbow is original.  I'm slowly learning that preventative maintenance is easier than fixing things in exotic locations.

Recently the engine's exhaust has been smoking and the engine has showing some signs of overheating.

Have a look at the exhaust passage of the old elbow and compare it with the size of passage shown in the new mixing elbow.  Note the old elbow opening is probably 1/3 the area of the new one.  Poor engine couldn't breathe...

Engine Troubles

We've been enjoying the serenity of Cala San Francisquito; hiking, swimming, diving, reading, relaxing and recovering from colds but Bay of LA is still calling me. I really want a chance to see the whale sharks before they migrate again (we've just missed them twice). So despite the forecasted light northerlies, we had an early breakfast and caught the flood tide north.
We were just heading out the narrow entry when Evan noticed we had no cooling water coming out from the exhaust. Then he made a quick check of the engine and saw there was no water in the cooling water strainer. I throttled back and got the second engine going (we have an outboard for manoeuvring). Once we were clear of the rocky entry channel we shut down the diesel and made our way back into the anchorage by outboard alone.
After dropping the hook, Evan began checking for the obvious problems: the impeller looked fine, the pump belt was fine, and the strainer was clear. The next step was to head over the side and check for a blockage in the thruhull. We've been getting a lot of barnacle growth in these nutrient rich waters—so we guessed the thruhull might be blocked by growth.
Evan jumped over the side in his snorkel gear and began prodding at the fitting with a screw driver. To his surprise, rather than finding barnacles he discovered a small, disoriented fish. The fish had been subject to a fair amount of discomfort in his new home, but he swam off and seemed no worse for wear. When we fired the engine back up the cooling water did what it was supposed to.
So after saying a second goodbye to the other boat in the anchorage we pulled the anchor back up and headed back out. Our early start was now a late start—which is par for the course with us... The light northerlies (that we tried to avoid with an early start) had filled in and the current we hoped to ride was diminishing.
But we're underway and our fish is in search of a new home.
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This whole moving aboard thing is taking its toll on me.
I'm not sleeping very well.
I wake up in the middle of the night with disturbing thoughts like, "Why is the boat's engine cutting out when it idles? Do we need a mechanic? What happens if we're going for fuel at a crowded fuel dock and a fisheries opening is called and the engine cuts out and I don't hear it because huge fishing boats are motoring past at high speed, rushing to get to the fishing ground because if they're late they'll lose out and won't be able to make their house payments? Could our boat be damaged?"


That was last night's worry.

The night before it was, 'What happens if someone calls for our Craig's List sofa and they come alone and are really little and need my help to carry the sofa down our 3 flights of stairs? Could I re-injure the torn ligaments in my knee from the strain? And if I do how will I get in and out of the dingy?"



The good news is Evan's incessant googling on the idling problem led him to discover that our engine's governor needed adjusting. He just called to say it's fixed! And the couch was taken by friends last night. So hopefully I'll sleep well tonight.

Although I am concerned that the floor above the port water tank has been creaking and in rough seas a seam could pop and then the whole thing might rupture and then we'd be sloshing around trying to fix it while a freighter, which we may have missed on the radar, bears down on us...