4BY3-150

The 4BY3-150 is part of the BY3 series (4BY3-150, 4BY3-180, 6BY3-220, 6BY3-260), the third generation of Yanmar's BMW-derived pleasure-boat diesels, which replaced the BY2 on Yanmar's line-up around 2013 with unchanged ratings. The engines use a 1.995-litre four or 2.993-litre six (84 x 90 mm), a 15-degree inclined block with double overhead camshafts and hydraulic valve adjustment, Bosch common-rail injection at 250-1600 bar, a wastegated turbocharger (MHI on the four, Holset on the six) and a seawater-cooled charge-air cooler; all are rated at 4000 rpm. A related 160 mhp sail and small-craft rating, the 6BY3-160, was added in 2015.

According to the BY3 operation manual, models without a suffix are for marine-gear installations (Kanzaki KMH41A on this model) and models with a Z suffix are for sterndrives, either Yanmar's ZT370 or MerCruiser Bravo 1, 2 or 3. Control is Yanmar's 'Classic' (hybrid) or 'Unlimited' (electronic CAN-bus) system.

Yanmar developed the 4LV series, on sale from 2017, to replace the 4/6BY engines, and yanmar.com now lists the BY3 with 'Legacy' status.