Large Outboard Engine Surveys (V8 - V12)

Why is a Large Outboard Engine Survey so Unique? Large outboard engines (high horsepower, eight cylinder to 12 cylinder outboard engines) require a lot more work and advanced training compared to smaller outboard engines. Large outboard engines require very specific training to properly service, diagnose, repair, and survey. Large outboard engine surveys typically take longer to inspect and test than a comparable four or six cylinder outboard engine. Large outboard engines typically are rated at higher horsepower, produce more torque, endure more load, and propel larger vessels through the water. Large outboard engines typically have more electronics integrated into them and are mostly digitally controlled. Larger outboard engines cost more to purchase and to maintain compared to smaller outboard engines, therefore large powerhead engine surveys require a more in depth, comprehensive mechanical inspection. This is crucial for evaluating the health of the outboard engine (or multiple engines). These specialized outboard engine surveys are important before a prospective buyer or owner purchases the vessel, renews the insurance on the vessel, considers warranty repairs or manages the maintenance of the outboard engines.
In many cases, larger outboard engines are the most expensive components of the vessel. Typically larger outboard engines cost anywhere from $45,000.00 to over $77,000.00 per engine.
The inspection process and testing of large outboard engines during the marine engine survey require some (or all) of the following (depending on the year, make, and model of the V8 - V12 outboard engines):
  • Sea trial (running the engines at wide open throttle, backing the engines down, and hard over turns to inspect the steering assembly and joystick controls)
  • Digital integration checks at the binnacle, digital gauges, and joystick (if equipped)
  • Compression testing
  • Borescope viewing of the cylinders, pistons, and lower unit exhaust passages
  • Inductive testing of the ignition systems
  • Infrared thermal imaging of the powerheads and transmissions to ensure proper temperature anomalies throughout the engines while running
  • Computerized marine engine diagnostics (includes dynamic testing, static testing, and component activation of the engine's components - to learn more about marine engine diagnostics click here)
  • Inspection of the steering assembly (digital integrated or bolt on 12 volt / hydraulic steering systems)
  • Inspection of the engine's electrical actuators or hydraulic systems
  • Oil analysis to search for unusual wear metals and foreign substances in the engines
  • Testing of the fuel to search for phase separation, contamination, excess water or Ethanol in the fuel
  • Sampling the two-speed transmission fluid (Mercury V12 outboard engines only)
  • Proper rectified and regulated voltage to insure the engines are charging the batteries when running
  • Running a search through databases to search for warranty history and fix campaigns (service bulletin related repairs that are needed on the engines)
  • An overall visual inspection of the engine to look for things such as galvanic corrosion, back probing, worn timing belts, proper belt tension, proper wiring connections, improper previous repairs, etc
Below are some of the most common larger outboard engines I am qualified to survey:
  • Mercury Verado V12, 7.6 liter 600 HP outboard engines
  • Mercury Verado V10, 5.7 liter outboard engines
  • Mercury Verado V8 4.6 liter outboard engines
  • Yamaha XTO Offshore V8 5.6 liter outboard engines
  • Yamaha F350 V8 5.3 liter outboard engines
  • Honda BF350 V8 5.0 liter outboard engines
If requested or recommended, I can conduct more advanced inspections and testing during the marine engine survey or analysis. I can also provide diagnosis or determine the mechanical failures. These advanced inspections and testing I can perform are detailed here
Below are photos from large outboard engine marine surveys I have conducted in the past:
Sea trial of a vessel rigged with quint (five) Mercury Verado V12 600 HP outboard engines
Outboard engine survey of twin Mercury Verado V12 600 HP engines after the upper and mid section cowlings were removed
Outboard engine survey of quad Mercury Verado V10, 5.7 liter, 425 HP outboard engines
Outboard engine survey of twin Yamaha XTO Offshore, V8, 5.6 liter, 450 HP outboard engines
Leakdown testing of a Mercury Verado V10 400 HP outboard engine to test for suspected power loss
Conducting dynamic marine engine diagnostics on a Mercury Verado V12 600 HP outboard engine. The oxygen sensor is shown to be at a default setting and not adjusting making fuel trim not possible on this powerhead (faulty O2 sensor)
A loose camshaft to camshaft timing chain on a Mercury Verado V8 4.6 liter 350 HP outboard engine (during a more advanced engine survey)
This two-speed ZF transmission was pulled from a Mercury Verado V12 600 HP outboard engine. The four proportional valves can be seen
The crankcase oil seal on just under the flywheel was leaking on a Mercury Verado V10 outboard engine
Pulling the transmission fluid from the ZF two-speed transmission for inspection on a Mercury Verado V12 600 HP outboard engine
Monitoring fuel pressure during an outboard engine survey of the Mercury Verado V12 600 HP outboard engine survey
Marine engine diagnostics using Yamaha YDIS showing a faulty water pressure sensor on a Yamaha XTO Offshore 5.6 liter 450 HP outboard engine
Mid section inspection of a Mercury Verado V12, 7.6 liter 600 HP outboard engine after the mid cowlings and sound proofing blankets were removed
Lower unit inspection on quint (five) Mercury Verado V12, 7.6 liter 600 HP outboard engines
Removing the outer propeller of the dual propeller on a Mercury Verado V12 lower unit to inspect the shaft and shaft splines
Disassembling a Yamaha XTO Offshore, 5.6 liter 450 HP outboard engine for compression testing during an outboard engine survey
Borescope inspection of the intake and exhaust valves in the combustion chamber of a Mercury Racing V8, 4.6 liter 450 HP outboard engine
Borescope inspection of the cylinder and piston crown inside of a Mercury Racing V8, 4.6 liter 450 HP outboard engine
Infrared thermal image of twin Mercury Verado V12, 7.6 liter 600 HP outboard engines running (looking for unusual anomalies to indicate overheating or improper raw water flow in the powerheads)
Infrared thermal image of a single Mercury Verado V12, 7.6 liter 600 HP outboard engine running
Inspecting the remote mounted rigging center of a Mercury Verado V12 600 HP engine (verifying the rigging center is properly installed and with the optional MerCathode system wired in)
Checking for proper torque of the mounting bolts (going through the transom) on a Mercury Verado V12 600 HP outboard engine bracket
I am certified as a technician in several outboard engines, on specialized marine technologies, and have earned two SAMS® designations (Yachts and Small Craft and Engine-Gas). My combined training, education, and technical certifications can be found here. Please contact me if you would like to arrange a marine engine survey or engine analysis at (561) 255-4139 or via my contact page here. I would be more than happy to discuss it with you and can combine it with a pre-purchase and valuation survey for a prospective buyer. Capt. John Banister, AMS® SAMS® Accredited Marine Surveyor ABYC® Standards Accredited ABYC® Gasoline Engines Technician Certified Yamaha Certified Outboard Marine Technician Mercury Certified Outboard Engine Technician Mercury Certified V12 Outboard Engine Technician Honda Certified Outboard Engine Technician USPAP® Certificate on Appraisal Standards ITC® Certified Level III Master Thermographer USCG Licensed Master Captain Member SAMS®, ABYC®, IAMI®, & NFPA®
Suenos Azules Marine Surveying and Consulting - Palm Beach Gardens, Florida