Well, we finally got some parts in.  Our order from Defender.com came in which included a lot of stuff we needed for some critical plumbing.  It was time to go ahead and hook up one of the critical systems to the engine.

Critical engine systems to hook up:

  • Exhaust
  • Fuel
  • Raw water
Today’s agenda.  Exhaust.  Lets talk marine diesel exhaust.  Its exciting, I know, but just hang with me a second. 

Marine engine exhaust is a lot different than you might see exhaust in land based engines. To cool a marine engine the boat pulls water in from the sea and passes it through a heat ex-changer.  This is the function of a radiator in normal cars which pass air over through the cooling system.  So what happens to all this water being sucked in?  Well it is injected into the exhaust and sent out of the boat that way.  It is what is known as “wet” exhaust.  It has the added benefit of cooling down the exhaust so that only the exhaust manifold is really hot.  Once the water is injected things cool down significantly.

There is a danger in wet exhaust systems that the water can back siphon up the exhaust into the engine.  To prevent this the muffler must be down sloped.  Its also important to note that all connections must be double hose clamped because if any part of the exhaust lets go, it could start flooding the boat.

Our project today started by getting the muffler ready.  Since our space is very limited we had to use a muffler that had a smaller connection than the 2″ exhaust hose.  It was 1-7/8″.  To make up the difference I wrapped about an eighth of an inch of duct tape around the muffler connections.

I left a big portion of the original exhaust system in place.  I did this because replacing the whole thing would be a pain in the ass and the exhaust hose is very expensive.  I found the junction point between the new and old and got it ready.  I had to remove an old fiberglass elbow.  I used a heat gun to make the old exhaust hose let go.

Well I say that.  What I really did was put the exhaust gun on it and cussed its mother many times.  Ran a screwdriver around it, yanked, tugged, and generally had a rip roaring fight with it.

I won, but I was bewildered.  You can see the screw driver marks in the fiberglass from the battle.

I carefully measured out the new lengths of hose I’d need and cut them.  This exhaust hose is stout stuff.  It is very thick and has two wires inside of it.  To cut it I used a very sharp knife and some wire snips.

Everything connected up.  Notice the muffler is just sort of “floating”.  Held in place by the heavy duty hoses.  Behind the muffler I added a 90 degree fiberglass elbow to turn upwards to go meet the old exhaust system.

To join the older exhaust system I added a 3″x2″ fiberglass reducer.  The old exhaust system was 3″ and the new is 2″.

With dwindling daylight left I went ahead and replaced the cockpit drain hoses.  We used the same exhaust style hose for these critical drain hoses.  I pulled the old hoses out and measured them against the new.

The old hoses were over 20 years old.  They have “Malaysia” written on them. Evidence of the Firey’s refit when they repowered in Malaysia.  I used the same method to cut these.

Tada,  new cockpit drain hose.

These drains work because the drain is above water level.  If water collects in the cock pit it will simply equalize with the water level outside the boat.  Since the drain hose could sink the boat if it busted or came undone, we double hose clamped it. Notice the 2 bands of metal at top and bottom.  Same drill with the exhaust hoses.

Tomorrow we’ll service all the seacocks.  I will have to tear the ones in the head completely apart since they are frozen in place.