Maintenance Spring

 No, not spring maintenance, maintenance spring.

It started back in November when one day, when we boarded the boat, the primary bilge pump was running.  Huh.  After a long afternoon of troubleshooting, I was unable to find anything wrong, so I put everything back together.  Weeks later it happened again.  I finally concluded that it had to be the float switch, even tho it seemed to check out OK.  I installed a spare that I had on board, and that took care of that.

Next, we found that the refrigeration system was not running.  Thankfully there was nothing important in either the refrigerator or the freezer.  Eolian's refrigeration uses a belt-driven compressor, powered by a 1/2 hp 12V motor.  That motor had given up the ghost.

Now, in 1978, the motor had quit similarly.  At that time, Eolian was moored at the south end of Lake Union, right in downtown Seattle.  Back then, before the huge influx of cash from Amazon et. al. gentrified the whole area, I pulled the motor and walked it to a rebuild shop that was conveniently located near the marina.  Now however, I had a great difficulty in finding a rebuild shop.  I finally settled on a local automotive parts store who claimed to have a "relationship" with a major rebuilder down in Seattle somewhere.  I dropped off the motor.  Weeks later, having heard nothing, I called and was told that it would cost more than $700 because "...there were several small things inside that were no longer available and would have to be constructed from scratch by skilled machinists."  This not being my first rodeo, I recognized bulls**t when I heard it, and asked for the motor to be returned.  When I finally got it (another long delay), I tore it down and found a badly scored commutator and completely worn out brushes.  The bearings were pristine.  I also noted that no-one had actually disassembled the motor, despite the diagnosis I had been given.

So I ordered some brushes off of eBay for $6 and built a jig to turn the commutator, using an electric drill and a file.  I don't believe that the scoring was the result of wearing out the brushes.  Instead I think it was from that original rebuild way back when.  

Home made commutator turning jig

Before and after

After reassembly and re-installation in the boat, it worked great!  But...

While checking out the installation, I discovered that the Freon charge in the system was awfully low.  Getting that next maintenance item rectified was the subject of a prior post.  Been counting?  This made the third major maintenance item.

Finally, while topping off the water in the batteries, I discovered that the exhaust hose leading from the generator to its water-lift muffler had a big bubble on it and was leaking.  So, a trip to West Marine to get hose and a tube of silicone (has anyone noticed that the silicone manufacturers seem to have colluded to stop producing resealable packaging for silicone??!?). 

Installing the hose will happen this coming weekend, presuming that something else doesn't fail before then...

And to think that I was seeing this spring as an easy one...

Maintenance Spring

Frostline Marine Refrigeration

 

It seems that we are always ready to complain when a business fails to meet our expectations in some way.  But then we are silent when things go perfectly...  well this is one of those perfect cases.

Over the years (23?...) since Eolian's last refrigeration service, things worked well...  until the last year or so, when the refrigeration compressor would start, run for a few seconds, shut off, and lather rinse repeat.  Eventually tho, it would come on and run until it reached the setpoint.  I guessed that the refrigerant level had become so low that when the compressor kicked on, it would rapidly pull the suction side of the system down to the cutout pressure, and that this would continue until the entire system became warm enough to raise the refrigerant temperature to the point where its vapor pressure was above the cutout pressure.  So, after all those years, it was time for a recharge.

I tried to find someone in the Anacortes area, but no one was willing to take on additional work.

Looking further afield, I contacted Frostline Marine Refrigeration in Bellingham.

What a pleasant surprise!

Mclean was courteous and scheduled an appointment at our convenience.

When he arrived, he was prompt, fully equipped, familiar with marine refrigeration systems (quite different from domestic or industrial systems - not least because marine systems are so often crammed into almost inaccessible spaces), working on boats (protect varnish surfaces!), and most importantly, knowledgeable of refrigeration in general (I have two degrees in Chemical Engineering - trust me, I know).

He pumped the system down, removing the remaining R-409a (which was the replacement for the old R-12 back 23 years ago) and refilled the system with the newest and greatest R-12 replacement: R-417c.  And he was gone in 45 minutes.

If you have marine refrigeration needs, I cannot recommend Mclean and Frostline highly enough.

Frostline Marine Refrigeration

Perkins 4-236 Shop Manual

 

The Perkins 4-236 is one of those small diesel engines that seemingly got adopted for every use under the sun.  One of those uses was in boats, and Eolian has one.

Because I like to have documentation on Eolian's important bits, I wanted the shop manual for this engine, and thanks to the courtesy of Martyn Lancing of Lancing Marine in the UK, I now have one.

If you would like a copy, provide me with your email address via a comment or at the email address in the Contact page of this blog.  The shop manual is a PDF document and is 15 MB in size, so be certain that your email provider will handle a message that large.

Perkins 4-236 Shop Manual

Turn, Turn, Turn

Back in 1998, when I was spending my first summer living aboard Eolian, the 12V electric motor which powers the refrigeration system failed.  Back then, 23 years ago, I pulled the motor and walked up into the South Lake Union area to a motor rebuild shop.  A day later, I had the rebuilt motor back in hand and reinstalled it.

Fast forward those 23 years, and the motor has again failed - the brushes have worn out.  But now we are berthed in Anacortes where there are no motor rebuild shops, and the South Lake Union area is now all expensive high-rise apartments and businesses.

So this time, I decided to do the work myself.   First, I found that the bearings are in great shape - it is only the brushes need replacing.   Well, that and the commutator needs to be cleaned up.

(Quick lesson here for those not familiar with the internals of a DC electric motor.  The armature - the spinny part - has on one end a device called the commutator.  This is a series of pairs of copper bars, with the members of each pair on opposite sides of the armature.  Each pair member bar is the termination of one end of a coil of wire which, when powered, makes an electromagnet.  Things are arranged such that when the brushes contact the pair of bars and the magnet is powered up, it is just outside the field magnet and is strongly attracted to it.  But just as it gets there, the brushes break contact with that coil and make contact with the next one, via the next pair of bars on the commutator.  Thus the armature spins.)

Inspecting the commutator, it was obvious that it had seen arcing once the brushes had worn so short that they were not making good contact anymore.  But even more importantly, that motor repair shop which did the previous repair had done a very sloppy job of turning down the commutator.  First, they cut a trench that was just wide enough to accommodate the brushes, thus ensuring that if there was any play in the brush holder, the brushes would contact the edges of the trench and wear prematurely.  Second, they left a series of deep grooves in the commutator.  Now one might say, "Well, the brush will just wear to fit the contour of the commutator, grooves and all."  But again, if there is any play in the brush holder, then movement of the brush will defeat that reasoning, resulting in rapid brush wear.

So, OK - on to the repair.

I constructed a jig that would support the armature on its bearings, and connected an electric drill to the armature shaft.  This way, I could spin the armature while holding a file against the commutator, smoothing it out.  A lathe would have been much faster, but I don't have one.

 

It worked well, albeit slowly.  First I cut off the outboard wall on the commutator, making it all the same diameter.  (I couldn't do this at the inboard end, because this is where the wires are connected.)  Then I filed the rest of the surface smooth, and followed with 100, 220 and finally 440 grit sandpaper.

Before and After

I think it came out great!  (In the before picture I had already done some cleanup.)

I couldn't find brushes of the correct size, so I bought some that were too big and ground them down to fit.  This was an easy job, but messy since they are made out of graphite, which ends up going everywhere.

I checked the bearings (they are sealed bearings); they are in perfect condition.

The motor is now re-installed, and we have refrigeration once again.  And all that refrigeration downtime gave me a perfect opportunity to clean the interior of the refrigerator and freezer compartments - so bonus!

Turn, Turn, Turn