Grumpy Engine

I noticed on my trip down to Brunswick that my starboard engine was having some difficulty waking up in the morning. It would take an unusually long time to get it to start. Once it fired, it would seem to run fine and subsequent starts during the same day would be just fine, but that first start of the morning usually took 3 or more attempts to bring it to life. So, the past several weeks I've been looking into the issue as time permits.

The Westerbeke 42b Four Motor

My boat came with two 42 horsepower Westerbeke (or as my friends at the Retirement Project call them, Wester-Beast) motors. They have around 5000 hours on them, so I don't expect them to to be the youthful engines they once were, but the starboard engine should start easier than it does.

Diesel engines are relatively simple systems. When running, they have one less ingredient than their gasoline combustion engine counterparts. The engine compresses air in the combustion chamber. Then, when fuel is injected into the cylinder containing the compressed air, it spontaneously combusts producing power. No separate ignition system (spark) is required. Just fuel, air, and pressure. The closest thing to an ignition system a diesel engine has are a set of glow plugs. These are used to help warm up the cylinders to aid in cold engine starts. So, presuming that there is nothing screwed up in the timing of events (once it starts it does run just fine), the only real issues should be in the supply of air and fuel to the engine.

Combustion graphic from the University of Toronto

One time when I was trying to get it to start I noticed no signs of combustion. I would crank the engine, but no smoke or anything from the exhaust. I stepped away to think about it (ok, to curse at the engine), then came back and tried once again.  It fired up just like a new engine as if there was no problem at all. This got me thinking that I might have a fuel leak and air was getting trapped in the fuel line. Once the air was purged, the engine would fire.

So, I crawled into the engine compartment and looked for leaks. Sure enough, I found one very small fuel weep at a fuel line return fitting. Could this be causing air to be trapped in the fuel line? I tightened up the fitting and tried starting the engine again. This time the engine would not start at all. By sealing the leak, I trapped air in the line and it could no longer bleed out of the leak. I went back down, loosened the fitting again, and got the engine to start. I then re-tightened the fitting to stop the leak.

Feeling pretty good that I might have resolved the issue, I let the engine sit for a couple days to see if the problem was gone. Unfortunately, when I next tried starting the engine, the problem still existed. It might have been a bit easier than before, but if so it was not by much. Since then I've replaced the fuel filters and verified the fuel pump was working, but I am running out of things to try.

Guess I'm starting to see why they call it a Wester-Beast.