One thing leads to another

So goes it with boat projects.  Pick a simple project to work on such as changing the oil & filter, and it mutates into something much more involved.  The snowball effect.  I should know this by now.

I’ve come to realize that diesel engines don’t like to sit unused for extended periods of time.  Fuel goes bad, oil gets all goopy, seals and gaskets dry out and start to leak.  It’s been just over two years since our engine was last ran, and now seemed like good a time to do a little maintenance and fire her up once again.

Oil change pump

Since there’s no way to get to the drain plug on the bottom of the pan, changing the oil on our engine requires one to suck it out through the dipstick tube with a hand pump.  This involves running the engine for a bit in order to warm the oil to the point that it easily flows up the dipstick tube.  However, in order to start the engine to warm the oil I needed to hook up the raw cooling water supply hose that I had disconnected quite some time ago during the refrigeration project.  We also figured now would be a good time to upgrade our raw water strainer since the old one was undersized, corroded, and quite solidly plugged with debris.  The hose clamps that keep the ocean on the outside of the boat were also looking none too good, so I went ahead and changed all those and doubled them up as a redundant measure of safety.  And, as long as I was down there behind the engine, I should probably repair those corroded bonding wires that connect all the through-hull fittings to the cutlass bearing on the propeller shaft.  Remember the snowball?

Raw water strainer
Groco raw water strainer

New seawater strainer installed (double hose clamps)
Bonding wires reconnected to cutlass bearing

Once that was all back together it was time to change the raw water pump impeller on the engine.  After a couple years of sitting in the same position the vanes had developed a set, dried out and became brittle, and would most likely have disintegrated shortly after startup.  Luckily, or boat came with a couple spares and that was a fairly quick and easy fix (once I changed out the old eccentric cam and corroded locking screw).  I used Permatex 2 form-a-gasket instead of the flimsy paper gasket on the pump cover.

Cam assembly installed
New impeller installed

Just prior to turning the key and hitting the start button, I went ahead and changed out the zinc pencil in the heat exchanger.  The zinc is a sacrificial anode which oxidizes at a faster rate in seawater than the surrounding metal (copper), thus protecting it from corrosion.  The old zinc was completely dissolved and judging from the amount of corrosion on the outside of the heat exchanger, it appeared as if there hadn’t been one installed since long before we owned the boat.

Corroded heat exchanger

With the seacock open and the raw water side of the cooling system flooded, it only took a couple of cranks of the starter before she fired right up and purred like a kitten.  Well not actually like a kitten, but more like a steel drum full of rocks.  That’s just the way a diesel engine sounds, but it was music to my ears after two years of silence.  The wet exhaust was spitting water as it should, the oil pressure gauge was reading a steady 65 p.s.i., the tachometer was showing an idle rpm somewhere around 700, and the water temperature gauge was slowly climbing up to operating temperature.  With the engine idling, I made a quick check of all the new hose connections and water pump cover.  Thankfully, nothing I “repaired” was leaking.  Unfortunately, there was a small drip, drip, drip coming from the weep hole at the bottom of the water pump which is indicative of a bad shaft seal.  A quick check of the heat exchanger at the rear of the engine, I found another drip, drip, drip where the zinc screws into the housing, and no amount of tightening would stop it.

Remember the snowball effect?  I went ahead and let the engine warm for a few more minutes so I could at least drain the oil, but it was starting to become clear that I was due for a bit more work on the engine in the coming days weeks.  Stay tuned for part 2 (and maybe even a part 3) on how a simple task like an oil change turned into a way bigger project than I ever expected.  But then, it is a boat after all, and an old one at that.  I should’ve known better than not to expect it.

Merry Christmas & Happy New Year
Snowball Effect (Part II)