Yanmar Exhaust Class

[GaryMayo]

I am new to sailing again, sat out twenty plus years. My reentry went from 14' daysailors in my youth to my current affliction, (see signnature )

This fall I winterized my Yanmar 8hp single piston diesel, and I am still doing some head scratching.

Winterized it twice.

First time, ran PG pink through system from strainer before engine till two gallons of pink came out the exiting thruhull.

Came to realize I did not run the engine very long, and became afraid I may have left some water in the block behind the thermostat.

Called a Yanmar dealer, and he suggested I do it again with a warm engine or remove the thermostat.

Winterize X'2.

This is the first time this sailboat has seen sub freezing temps, as it was a California boat before I imported her to Nebraska.

My question in this. Why the odd (odd to me) arrangement of mixing the exhaust fumes with the discharge water from the cooling system, and just how much does it mix? I see the mixing elbow, but there is another box under a aft cabin berth I do not understand.

[Target9000]

I'm assuming the box under the aft cabin berth is the water lift muffler.

In a car or aircraft engine you have the luxury of lots of moving air. This allows you to use a radiator to remove excess heat from the engine. On an inboard diesel you don't have that so instead you use water to "heat exchange" and remove the heat from the boat. Since you're pulling water in, you have to spit it out somehow, and the most logical way to do that is to spit it out the same exhaust as the exhaust gases. This has the added benefit of cooling the very hot exhaust gases before they exit the hull. That is my understanding of the "why".

[djmarchand]

It sounds like you have a raw water cooled engine. In that case the pump picks up water from the thruhull intake pumps it through the block where it cools the engine, then to the exhaust injection elbow where it mixes with the hot exhaust gas and cools it so that it won't harm the fiberglass water lift muffler which pushes the water in pulses up and out the exhaust.

David

[NCboatrx]

A cool exhaust allows you the luxury of using easy to work rubber and plastic and fiberglass for the exhaust system. If you run a hot exhaust, you not only have the problem of heat in the boat, you also have a major fire risk.
Stanley

[Tingum]

If you are collecting the discharge water at the exhaust elbow make sure you either drain the muffler or pull a hose and dump some antifreeze into it.

[GaryMayo]

Originally Posted by Tingum

If you are collecting the discharge water at the exhaust elbow make sure you either drain the muffler or pull a hose and dump some antifreeze into it.

Collecting fluids at the exit thruhull to feed back into the pickup. It was a southern California sailboat, where none of this was necessary. Next spring I will be redoing a few hoses, and adding splitters and shutoffs to make the job easier. It was a royal pain in the neck.