Northern Lights… not the pretty ones…. Part 1

I wish I was writing about sailing adventures under the Northern Lights!

We knew during the purchase survey there was an issue.  The previous owner created a small list of known issues which included the Northern Lights M643 5kW diesel generator.  Although it only has 1200 hours, he mentioned the generator had an overheating problem and was most likely due to a lack of significant use.  We never wanted a generator in our ideal boat anyways, so no big deal.  Worse comes to worse, we scrap it.  We validated the overheating problem the first time we ran it.

Don't you love the pictures from the catalogs?  They look so clean!!

 

Knowing a little about diesels’ lack of tolerance to light use from our previous boat, I agreed with the root cause.  Shortly after buying our last boat, Consort, the Yanmar 2GM30 was harder and harder to start and then one day it would not start at all.  I called our diesel expert (brother in law) for some help.  Julie’s brother is a diesel, plus everything else on fishing boats, logging equipment, etc., mechanic in Ketchikan, AK.  After a few questions for me, he said the black smoke at startup was most likely a carboned up blocked exhaust and it was keeping the boat from starting.  I told him the engine hours were low (around 2000 hrs) and the previous owner rarely ran the engine above 2000 RPM, so it couldn’t be that bad.  He was even more certain it was the plugged exhaust and told me to start with the exhaust elbow and work my way back to the exhaust manifold and heat exchanger.  The Yanmar 2GM should be run at 80% its max RPM, meaning I should always run it at 2800 RPM with the occasional 3000-3100 RPM to really clean things out.

Fortunately it is easy to forget the troubles and remember the great times on Consort!

It wasn’t that I did not trust his advice, it was that I did not want to pull the exhaust elbow.  It was in the back reaches of the engine compartment that a small trained monkey would have a hard time getting to!  So I spent a couple weeks working on a fuel problem that did not exist.  Filters, fuel pump, fuel lines, fuel tank, fuel bleeding… you get the picture.  It was the exhaust elbow.  Many hours later of wasted time, I replaced it within a day and all ran fine for years to come!

So, all that experience paid off, right!  Well almost.  The antifreeze checked out fine. The generator started fine and I had some saltwater coming out the exhaust outlet on the side of the boat, so I started with the heat exchanger core.  It was not too difficult to drain the anti-freeze, pull the rubber end caps (boots in the picture below) off the exhaust manifold/heat exchanger and remove the core.  So I thought.  The rubber end caps came off as expected and the core slid out within about 1/2" of being able to remove it.  Bummer, I hit a wall, literally.  I had to get a hammer and wood chisel to remove 1/2” of wood from the inside of the engine compartment in order to get the core to come all the way out.

Who needs manuals when you have great fellow cruisers and YouTube to learn from!

 

A few hours later I had the core out.  Pretty straight forward, a bunch of tubes running through a larger diameter brass pipe.  I looked through all the tubes that the cool saltwater runs through and they looked pretty clean.  The outside of the tubes where the engine antifreeze (hot engine water) runs through looked clean as well.  I rinsed the heat exchanger core and put it back in.



Our core was definitely NOT this shiny.  Another catalog picture.

Hmmm.  Must be the saltwater pump/impeller, number 6 in the diagram below.  The pump was newer, an obvious attempt by the prior owner to solve the heating problem.  Took it apart and the saltwater pump and impeller looked fine.  Saltwater hoses were not blocked.  Direct drive, so not belts involved.

 

Here is the exploded view from the manual.  Shows you all the options which could be the problem!

 

Must be the engine (antifreeze) water pump (not in the exploded view above).  Pulled the hose (number 36 above) from the water pump to the heat exchanger/exhaust manifold.  It was clear.  Tried rotating the pump and it rotated easily.  Ahhh… wait a minute.  The pump rotated easily, but the belt that drives the water pump did not move at all.  Sure enough, the drive belt that runs the water pump and the alternator was loose!  This means the engine water pump was most likely not turning fast enough if at all!  No wonder it was overheating.

 

More to come on getting it all back together.