Return of Newton, grr!

After giving our Yanmar (engine) some new oil and filters I decided it would be a good idea to flush and change the coolant.

After some reading, it didn’t seem to be a big deal or take a whole lot of time either so I was thinking, ‘why not?’ There are a couple of drain hoses (seen in not my photo below) and a fill cap (also not my photo below). Pretty easy I guess.coolant-engine-yanmar-port-aft-quartercoolant-1

I’m not completely illiterate when it comes to some minor mechanic work.  The only issue is where some things change because of a marine environment, or use of specialty parts, or knowing which items are left handed threads instead of standard, or Japanese instead of British standard.

After draining the coolant, comes the flush.  I found a product that was safe for my engine (many are not) and followed the directions of fill, run, drain then fill again with water to flush clean, and repeat until water was clean.  Then fill back with new coolant.  Likewise this was ‘special’ coolant for my engine and it seems that everything about boats is ‘special’ which equals more $$.

Done, all drained, flushed, and filled back up.  Now to run the engine to check for leaks and temperature.

Engine runs and no leaks, but the exhaust sounds a little dry.  Dry you say? Isn’t exhaust supposed to be dry?  Remember boats are ‘special’.  Most marine engines have a part that mixes water with the exhaust to cool it, and reduce noise.  As seen here:


The small black with blue hose is for water, the silver pipe is exhaust (tailpipe) and they are mixed together and now wet exhaust is sent into the big black hose. Then it’s off to the muffler, then out as seen here:


This is not exactly my system but gives a good way to see how it works.

Back to my issue, remember my boat exhaust doesn’t sound wet anymore, it sounds very dry.  In fact, there was little to no water coming out with the exhaust.  What could have happened?  Remember my old friend Newton, for everything done, there is a equal opposite.  I try to make my engine run a little better, and something else breaks.

Come to find out this mixing elbow as its called, is a consumable item.  Meaning it’s only good for so long before it has to be replaced.  What can happen if it’s not replaced?  You guessed it, no wet exhaust.  As you can see in these photos, the elbow is almost completely clogged up .


This is where the water is supposed to enter but it’s clogged up too.


Yet another ‘special’ $$$ part, then clean up the other parts and put it all back together. While I was at it, I replaced the hoses for this part too. They were in poor shape and it only made sense to replace instead of waiting for them to spring a leak (no photos).





Finally after putting it all back together, start the engine to check for leaks, and at last it works.  No exhaust leak in the boat (very important) and no water leaks.  Check outside and Huston, we have wet exhaust.  This would have been devastating to have left unchecked and took off on a sail.  At least now we don’t have to worry about it for a few more years.

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