Bukh DV 24 ME diesel engine review

I had just about given up on reviewing a traditional marine diesel engines. All the marine diesels I’ve reviewed so far for this department have been marinised tractor and industrial engines, all compact, lightweight and electric-start units. Not so the Bukh DV 24 ME.

This engine has direct fuel injection, raised hand-starting with decompression levers and seawater cooling. It’s just like the diesels other European manufacturers offered before ever-tightening exhaust emission regulations killed them in favour of freshwater cooled engines with indirect injection and high compression ratios that just about wiped out any hope of hand starting.

The multi-cylinder engines range from the naturally-aspirated twin-cylinder Bukh DV 24 ME up to the inline three-cylinder turbo DV 48 ME. All have the same bore and stroke dimensions of 85mm and can be started by hand, a real plus for any long-range cruising yacht. Heat exchanger freshwater cooling is available but all of these engines were designed specifically for direct cooling which has way fewer components to fail.

Unusually, all the engines have continuous rating instead of intermittent, which partially accounts for their hefty weights over the competition.

BUKH DV 24 ME

The Bukh DV 24 ME has maximum continuous outputs of 18.8bhp at 2400rpm up to 23.6bhp at 3600rpm, equivalent to a 30bhp intermittently-rated engine at the same rpm. Part of the reason for this is that direct injection always gives more power per cylinder displacement than indirect injection, because the fuel is injected directly into the combustion chamber instead of a small pre-combustion chamber. Also the cylinder head runs cooler because there’s less thermal load on it.

The 964cc all-cast iron OHV engine has a gear-driven camshaft, reliable pushrod valve actuation and thermostatically controlled cooling to prevent overcooking, which can kill an engine as fast as overheating.

To reduce vibration, twin counter-rotating harmonic balancers are fitted and like all traditional small diesels the exposed flywheel is aft of the forward end of the engine. This enables the engine to be shoehorned into the bilge of older full-keel cruising yachts. There’s a simple belt drive to the 50amp voltage-regulated alternator mounted at cylinder head height with the 1.7bhp starter motor mounted not far below it. Theoretically the engine could run half underwater before the electrical system shorted out.

Having direct injection the compression ratio should be around 16:1, which combined with the large-diameter flywheel and decompression levers enables easy hand-starting. Back in my way slimmer days in the Aussie merchant navy I could easily start our direct injection Lister lifeboat and fire-pump diesels up to two-litres piston displacement. This was done by simply cranking over the engine several revolutions to prime the fuel pump then throwing off the decompression levers – so even if you have only a reasonable fitness level hand-starting the 24 shouldn’t give you a hernia.

The standard mechanical gearbox reduction ratio is 3:1, okay for displacement cruisers but a bit deep for yachts. However there are 2.5:1 and 2:1 options.

Servicing the DV 24 appears straightforward with the canister oil filter easily reached and mounted so it won’t dribble oil all over the crankcase when replaced. Oil and filter change intervals should be every 100 hours or annually and a diesel-grade SAE 15W40 oil will suit most climates.

All this sensible engineering comes at a price. At 210kg dry weight the DV 24 is as heavy as a 40bhp marinised tractor engine, partially compensated by the very good torque delivery comparable to a 30bhp tractor engine at the same rpm. And measuring 845mm long by 470mm wide and 640mm high, it’s as bulky as a 35bhp marinised tractor engine. So it’s viable only for repowering a full displacement cruiser or keel boat.

The maximum static installation angle is 12-degrees with up to 25-degrees of heeling acceptable underway – good for motorsailing. The standard instrument panel lacks a tachometer and hour meter, so I’d be hitting up your local Bukh agent about that one!

THE TRADE-A-BOAT VERDICT

Bukh seems to be trapped in a time warp. The DV 24 has been around as long and unchanged as I can remember, but that’s a good thing. Its engineering takes me back to a time when hand-starting was the norm, with electric starting an option – a time when the ability to start an engine was way more important than any exhaust-emission compliance.

After all, who cares about that when the starter battery is flat?

The DV 24 has the true mechanical essence of what a small marine diesel is all about!

For more information on the Bukh DV 24 ME contact Graham at Bukh Diesel Australia, phone (02) 9525 0011.

BUKH 24 PERFORMANCE

Torque and fuel consumption. Maximum torque at low rpm makes the Bukh DV 24 a good choice for powering hefty cruising boats. The direct injection also gives good midrange fuel efficiency

BUKH DV 24 ME DIESEL ENGINE SPECIFICATIONS

TYPE Two-cylinder diesel marine engine

RATED HP 23.6 at 3600rpm

TORQUE 57Nm at 1800rpm

DISPLACEMENT 964cc

BORE X STROKE 85 x 85mm

WEIGHT 210kg (dry w/gearbox)

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Originally published in Trade-A-Boat #456, August / September 2014. Why not subscribe today?