top of page

Mercury diesel-powered engines give you unparalleled durability. Thermostatically optimised closed-coolant systems. Advanced control systems. And ultimate corrosion resistance. These engines are built to go the distance.


Mercury diesel leads the industry in power-to-weight ratios, delivering heavy-duty propulsion in a lightweight package. For you that means quicker acceleration, faster planing, and improved maneuverability. Higher efficiency, too. Another bonus.


Advanced intake systems keep Mercury diesels running easy and clean. None of the harshness or fumes from traditional diesels. And an increase of up to 50 percent in fuel efficiency compared to gas engines of the same horsepower. More reasons to go Mercury diesel.


Quiet Ride.

The high-pressure common-rail fuel-injection system not only ensures fuel economy, it also minimises Noise, Vibration and Harshness (NVH), along with smoke and odor – the undesirable factors many boaters associate with yesterday’s diesels.


Repower Reasons.

The lightweight, compact design of these diesel engines makes them ideal drop-in replacement power packages for many older, fuel-guzzling petrol engines. Mercury’s full range of drives offers outstanding versatility to owners of sterndrive-powered boats.


Peak Performance.

Impressive acceleration and quick throttle response are delivered by the proven common-rail fuel system, which incorporates a turbocharger and seawater after-cooler. These engines combine smooth performance with key diesel advantages, such as high torque and optimum fuel economy.


Intuitive Design.

A sophisticated Control Module and Mercury SmartCraft compatibility provide complete control over key engine functions. SmartCraft Digital Throttle & Shift (DTS) offers smooth shifting, immediate throttle response and high-tech digital controls.



Mercury diesels feature state-of-the-art anti-corrosion, including a thermostatically controlled closed water-cooled system. Water-cooled engine oil, gear oil and steering fluid decrease engine-room temperatures, extending engine life. The SeaCore® system is available for the ultimate in saltwater protection.


Mercury® Diesel: 4.2L (270-350hp)



Power mhp / kW
  • 350 / 257
Bore and stroke
  • 3.70 x 3.94" / 94 x 100 mm
Maximum RPM (WOT)
  • 3800
Engine type
  • Inline 6
Displacement (L)
  • 4.2
Dimensions (L x W x H)
  • 42 x 30 x 31" / 1077 x 773 x 790 mm
Weight (engine only)
  • 1014 lbs / 460 kg
Weight (incl. transmission)
  • 1111 lbs / 504 kg
Weight - Bravo Three
  • 1272 lbs / 577 kg
Cooling system
  • Closed cooling
Fuel consumption
  • 21.5 gal/hr / 81.46 l/hr @ 3800 rpm
Compatible drives
  • Bravo Three
  • EPA Tier 2 IMO RCD BSO/SAV certified


Price advertised is for the 4.2L inline 6, 270HP, Mechanical - Engine Only

Please Note: Transoms & Sterndrives are additonal 


Mercury Bay Marine are you're Mercury Outboard specialists that service the coromandel and wider Waikato areas


Call our sales team today 6 days a week for any further information or if you would like a complete quoted driveaway price


Trade ins welcome


Nobilo Finance


We can also provide access to competitive finance options available through Nobilo Finance, so talk to us today on how we can provide this service to you


Mariner Marine Insurance


Mercury Bay Marine are an authorised agent for Mariner Insurance, click the link below to get a quote for insurance

Mercury® Diesel: 4.2L (270-350hp) - 270HP Mechanical

    Mercury Bay Marine price match
    bottom of page