Yanmar 6LY3-STP – Inboard Diesel Engine 440 HP

Vessels demanding high power density for sportfishing or charter work can utilize the Yanmar 6LY3-STP. This 5.813-liter inline 6-cylinder diesel engine generates 440 horsepower at 3300 RPM, giving planing hulls strong acceleration. Electronic common-rail fuel injection optimizes fuel atomization across all throttle settings, keeping mechanical vibration low and exhaust smoke minimal during dock maneuvering.

Closed freshwater heat exchanger cooling protects internal block passages from saltwater corrosion. Built on an SAE 3 flywheel housing, the engine includes a 12V 80-amp alternator, an 18-liter oil sump, and a dry weight of 640 kg (1411 lbs) without marine gear.

Helm Use and Readability

High power output combined with inline 6-cylinder smooth firing makes this Yanmar inboard engine a trusted propulsion choice. Forced lubrication safeguards internal crank journals, while the water-cooled exhaust manifold keeps engine room ambient temperatures low.

Why Choose the Yanmar 6LY3-STP Inboard Marine Engine

Captains select the 6LY3-STP marine engine for its proven 5.813-liter block and strong 440 horsepower rating. Its electronic common-rail fuel delivery and intercooled turbocharging provide rapid planing performance without heavy soot. Closed heat exchanger cooling, SAE 3 housing compatibility, and robust construction make it a top repower choice.

Warranty and Support

Yanmar covers this engine package with a 2-Year Limited Recreational Warranty protecting against manufacturing defects. provides product-information support before purchase and assistance with order-related questions. A pre-shipment visual inspection confirms the engine crate and documented included rigging items. Review warranty eligibility and current coverage details on before placing your order.

Before Ordering the Yanmar 6LY3-STP Inboard Marine Engine

Measure your engine room length and hatch access dimensions for an inline 6-cylinder block. Confirm your marine transmission ratio, propeller shaft coupling dimensions, and fuel line sizes before placing your order.