Light rebuild of our engine… and a little oopsy

If you read the previous post – you know about our slight lapse of judgement when we sold the boat and bought it back. When we bought it back the engine was not running and we didn’t know why for a while, but we happened to have a philanthropic diesel mechanic (“Diesel Bob”) on the same dock as us who helped us do some diagnosis. Upon digging in a little we found coolant in the intake manifold.

Coolant? In the intake? This is an old fashioned diesel, there are no water jackets in the manifold so the only way it could have gotten there was if it backed up through one of the cylinders. Begin the teardown.

The first inclination was a cracked head gasket, but after Bob inspected the head and the gasket he determined that not to be the case. He couldn’t rule out a crack somewhere in the head that might be causing coolant to leak into one of the cylinders – so I took it to a shop and had them do a pressure and magnaflux test. Both came up clean, but they did replace some valve stem seals. This step in particular introduced another pretty major problem that I’ll talk about later…

The next suspect was the coolant tank / exhaust manifold. There appeared to be some corrosion between the exhaust port and the manifold side which *could* have been enough to cause coolant to seep into the exhaust, fill up the exhaust hose, fill up the cylinder and overflow into the intake manifold. Ok, maybe a stretch, but the boat was sitting on the hard for a year, so it was feasible for that to happen.

Upper right quadrant of the circle is the area of suspicion

The whole manifold is made from a single piece of cast aluminum. Somewhat nearby (so it was not too bad on shipping) was Marine Exhaust Systems of Alabama ( – they were able to fill in the corrosion successfully. While it was out I also made new gaskets and installed new studs, because why not? I reassembled the engine, nearly breaking my back in the process (do you know how heavy / awkward it is to maneuver a cylinder head around??), and started the engine…. not!

Still wouldn’t start.

Was all of that time / money wasted? I hope not, perhaps it was good / healthy for the engine in some way. Eventually I pinpointed the root cause to the fuel pickups – we have two – a “mid” tank and a “lower” tank. Both of the valves were turned on, but if the tank is low (which is was) it would have been sucking air into the line. So the problem the whole time was air in the fuel line and after some wicked long fuel line bleeding time it did start up. I think the idea behind the mid tank pickup is that it would be less likely to get clogged? If you know why this exists let me know in the comments. I leave it off now.

But the story doesn’t end there!

After about 30 hours of motoring on the ICW, about 10 miles north of Daytona Beach I noticed the engine tone sounded different, then a few minutes later the RPM dropped a hair, then another few minutes later we lost a cylinder on the engine. More specifically, it was obvious that the intake valve on one of the cylinders was not sealing, causing loss of compression, but not quite enough to stop ignition, so we could hear a loud pop-pop-pop from the engine. We dropped the engine down to an idle, called a tow boat and slowly meandered down the ICW.

Teardown #2 found that the rocker shaft had broken in half. This is the major problem I mentioned earlier. Unfortunately this one was my fault, I did not realize that the shop which did the tests on the head had disassembled it and did not torque the bolts to spec when they assembled it (apparently this is standard assembly practice for them?) The bolts were probably only hand tight when I reassembled the engine, and as you can see in the photo totally backed themselves out from the vibration. This caused the shaft to flex until it broke.

That doesn’t look right.

Either way, I’m anchored in Daytona Beach with a 48 year old disabled engine that no one makes this particular part for. I’ve been able to source many of the consumable parts (gaskets and such) from Northwoods Tractor, as the Westerbeke W80 is just a British Leyland 4/98, but this is not a part that anyone stocks. Fortunately Transatlantic Diesel has a number of these engines sitting around and was able to find a complete rocker shaft assembly for me, complete with rockers and brackets, for only $400! Less than half a boat buck, how about that?

Old shaft (top) and new shaft (bottom). Electrical connector for scale.

This time with the shaft properly torqued the engine fired right up! In this case we dodged a bullet and our 48 year old engine is still keeping us going!

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