New engine calculations

A new engine is a big challenge, not just financially but in the thought process running up to the decision.

Our Volvo is 30 years old and we had it taken out and largely rebuilt 10 years ago. It has been reliable since then but this winter it has been increasingly difficult to start, and the expert verdict was that the valves probably needed regrinding.

There is no space to do this without taking the engine out, and so the bill would be at least £1,500. Experience tells us that whenever you take an engine out and the cylinder head off, other problems turn up, and since the engine is already out (expensive in itself) it then makes sense to put them right.

That was exactly what happened 10 years ago, and the cost escalated so we ended up spending nearly half the fully-installed cost of a new engine. That has in the end proved worthwhile, because it has lasted 10 years.

The fine judgment this time was whether to take that risk again, or put the money towards a brand new engine with a 5 year parts guarantee. The idea of a new engine proved in the end more attractive than a second reconditioning, mainly because of the uncertainty about what else we would find out about the old one, but also because it would be more reassuring at sea.

One other factor is the rule of thumb one often hears that the value of a boat improves by roughly half the cost of a new engine. Evidence for that is hard to come by because there will rarely be a counterfactual (in the shape of an identical old boat for sale with identical equipment and condition but an old engine). But it’s a good way of persuading yourself that the true cost is only half what you are paying out.

The engine itself is only the beginning, of course. I’ve only bought one new engine before, for a previous boat, but this is repeating the same pattern: very broadly, professional labour costs are in the region of 40 per cent of the cost of the engine itself. Then there are the costs of converting the engine to fit, though in this case we chose a Beta Marine engine marinised in Gloucester from a Japanese Kubota truck engine, partly because they are pre-adapted to replace Volvo Pentas at only modest extra cost.

Almost inevitably we needed a new propeller to match the new engine, and a rebuild and partial replacement of an old exhaust system. Then we had to add new parts to connect up the boat’s hot water system and finally a new prop shaft because the old one on close inspection turned out to have some corrosion pitting. The total cost is heading for nearly twice the cost of the engine itself, similar to the outcome for the previous new engine, which also had the additional expense of a rebuild of the engine bed. This time there’s one vital difference: shared ownership, so 50% of the cost each.

Installation is not finished yet, but we hope to launch and test the new engine next week. Fingers crossed!

In place, not yet jnstalled

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