Diesel Engine Longevity

The meter on my Perkins 4-236 diesel engine just turned over 12,000 hours, and I'm only responsible for about 4000 of this. Over the course of forty-five years and a circumnavigation Charlene (I don’t know why my diesel engine is named this) has had routine maintenance, and lots of components replaced, but she’s never been rebuilt.

In the fifteen years I’ve owned the boat, the engine has only failed to start with a touch of the key twice: once because it was too cold in New Zealand, the other a few weeks ago when the starting battery was shot. That’s what I call a reliable piece of equipment.

Diesel engines are truly remarkable in their simplicity and reliability. They say that with a snorkel air intake, a diesel can run underwater. Diesels make their wasteful gasoline burning cousins, with their complicated electrical systems and wimpy compression ratios, look like Rube Goldberg contraptions.

Ten to fifteen thousand hours seems to be the zone for rebuilds on diesels in the boating world. This is a lot of hours! My four thousand hours over fifteen years and a circumnavigation equates to roughly 25,000 miles of motoring, and this only represents a third of my engine's life.

As long as we obey the Holy Quad—clean oil, clean air, clean fuel, clean engine—as expressed by routine maintenance, we can all expect long, happy lives from our diesels before they need to be rebuilt.

And rebuilding isn’t the end of the world. A complete rebuild kit for my Perkins 4-236 costs less than $1000. The problem is getting the engine out of the boat (not entirely necessary, but probably recommended) and all the labor. If you’ve got the space (t’would be nice to have some dedicated shop space), and the time, anyone can rebuild their own engine with just a few key jobs sent out to a machine shop.

Herr Doktor Diesel, the inventor:

But I’ve had another test case throughout my life, our family business, the Balboa Island Ferry. We recently had to replace all the engines with California emissions-compliant John Deere diesels, but for the sixty years before that we ran six cylinder Fords.

There are three ferries, and we keep two spare engines in the shop. One of the spares is completely ready to go—plug and play—the other is a rebuilt block, which would need a cooling system, starter, pumps, et al before it could be put into service. We can drive a pickup truck with a hoist onto the ferry to swap engines. The record for this operation is three hours, on a 4^th of July, when we had cars stacked around the block and down Park Avenue.

Given this quick turnaround for engine swaps, we run our engines into the ground, and I can’t recommend this practice for a cruising sailboat in the hinterlands. And our engines represent a very different usage pattern than a recreational boat: these engines are run 24/7 sometimes, and could run though a whole life cycle in just a few years (there are 8765 hours in a year).

The average number of hours before a rebuild, over the course of sixty years was about 20,000 hours. Often engines would go to 23,000. The record was 26,000 hours. 26,000 hours! That’s three entire years running 24/7, and just before a rebuild: the same engine block and major components ran for all sixty years.

That’s what I call a reliable piece of equipment.