Comprehensive Yanmar 4LHA-STP Marine Engine Survey conducted by Jeff Lendall & Sons – 805 Marine Diesel Mechanic for a 36.4-foot vessel. This technical inspection included complete diesel engine evaluation, fuel system assessment, cooling system analysis, exhaust inspection, and sea trial verification. The goal of this report is to provide transparent, data-driven insights for owners and brokers seeking a professional marine engine survey in Ventura, California.
Conducted by: Jeff Lendall & Sons — 805 Marine Diesel Mechanic
HIN/IMO: SHSM37145M79B OFFICIAL#: 937675 LOA: 36.4 FT
MARINE DIESEL ENGINE:
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Engine Make: Yanmar Engine Model: 4LHA-STP Engine Type: Inboard Power HP: 240 Fuel Type: Diesel Hours: 1372 Serial Number: 58296
- TRANSMISSION: ZF Marine Transmission ZF63-A
Yanmar 4LHA-STP engine evaluation confirmed that the diesel powerplant operates smoothly, maintaining optimal combustion efficiency with consistent idle and acceleration. The ZF63-A marine transmission engaged cleanly without clunk or lag. No leaks were detected from transmission seals or fittings, and the fluid appeared clean. Vibration levels were minimal, indicating proper alignment and shaft balance.
(ECM) Computerized Findings along with visual inspection:
Diagnostic scans showed no active faults on the Yanmar control module. Live data readings for oil pressure, coolant temperature, boost pressure, and fuel flow all tracked within factory parameters.
FUEL FILTRATION SYSTEM: Racor Turbine Series 10-micron filter assembly appeared serviceable, no water present. Fuel bowls were clear and seals intact—critical for maintaining diesel engine reliability during extended offshore use.
THROTTLE & SHIFTER CONTROLS: Morse controls operated smoothly at both stations. Response was immediate with proper synchronization between helm and engine, confirming control cable and linkage integrity.
SERIES TURBOCHARGER: Peak boost 37 psi at WOT (2300 RPM). Turbo bearings produced no abnormal whine; housing and clamps tight. Boost curve confirms turbocharger health and air delivery efficiency.
GEAR-DRIVEN SEAWATER PUMP: Seals dry, no corrosion at fittings. Flow rate was strong, ensuring proper engine cooling performance.
TUBE-TYPE HEAT EXCHANGER: Recently replaced; inlet/outlet temps within spec. Clean fins and end caps reflect consistent coolant maintenance practices.
ENGINE OIL COOLER: Checked inlet/outlet temps; within limits. No seepage or contamination detected.
ENGINE-MOUNTED FUEL COOLER: Operating normally; temperature delta stable. System ensures optimized injector performance.
SEAWATER PUMP OUTLET PRESSURE: Flow sufficient, consistent with rpm rise.
COOLANT LEVEL SENSOR: Fully functional. Coolant level stable across duty cycle.
AFTERCOOLER: Recently serviced/new; airflow density met factory specs. Proper intercooling sustains engine efficiency and longevity.
ENGINE MOUNTS AND BED: Clean, rust-free, secure. No deflection under load—important for vibration control and shaft alignment.
LUBRICATION: Oil level normal; viscosity within limits. Lubrication system stable across temperature range.
LUBE OIL PRESSURE: 58 psi at 100% load. Consistent with Yanmar 4LHA-STP specifications.
VENTILATION: Squirrel fans operational; compartment airflow adequate.
COOLING SYSTEM TYPE: Fresh-water reservoir with seawater-cooled wet exhaust; operated normally.
SEAWATER STRAINERS: 1.5-inch Groco bronze alloy; clean, well maintained.
COOLANT LEVEL: Stable at 20 psi pressure test; no drop observed. Surface temps verified with IR gun—system tight and efficient.
HOSES AND CLAMPS: Double-clamped 304 SS and high-temp silicone; all secure. Ensures long-term cooling system durability.
BELTS AND PULLEYS: Minimal wear; proper tension.
SEACOCKS AND STRAINERS: Ball-valve type; smooth operation.
EXHAUST SYSTEM: New installation with fresh lagging; no leaks; operated normally. High-grade silicone hoses double-clamped for safety.
ENGINE ALARMS: Low-oil, water-in-fuel, and overheat alarms audible and functional.
ENGINE SHUTDOWN: Clearly marked buttons at both stations; tested OK.
STUFFING BOX: Clean, greased, and leak-free. Dripless seal integrity confirmed—important for prop shaft sealing and bilge dryness.
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SEATRIAL REPORT:
The sea trial was performed under moderate conditions with full fuel and water loads. Start-up was immediate, idle steady at 700 RPM, and engagement smooth. Engine acceleration linear through cruise to WOT (2300 RPM). Steering and throttle systems were highly responsive.
1. Engine started without excessive cranking.
2. Exhaust and cooling water discharge normal.
3. Gauges held steady within specs.
4. Oil pressure and temperature readings matched ECU data.
5. Steering and control systems functioned flawlessly.
6. Transmission shifts smooth; no noise or leaks.
7. Back-down test confirmed propeller thrust integrity.
8. Rudder linkage tight and leak-free.
9. No oil or coolant leaks detected.
10. WOT Test: At 2300 RPM, boost 37 psi, clear exhaust—sign of excellent combustion and turbine efficiency.
Overall, the Yanmar 4LHA-STP marine engine delivered clean, powerful, and vibration-free performance—typical of a well-maintained diesel with balanced injectors and healthy boost pressure.
OIL ANALYSIS:
Oil samples were submitted for spectrometric analysis to evaluate metal content, fuel dilution, and oxidation. Results showed low wear metals and no fuel contamination, confirming the engine’s excellent internal condition and maintenance practices.
Yanmar 4LHA-STP Oil Analysis Report
FINDINGS:
The Yanmar 4LHA-STP engine ran exceptionally smooth with no smoke or vibration irregularities. Oil pressure, boost, and temperature profiles remained within ideal operating parameters throughout the sea trial. Visual inspection showed new hoses, belts, heat exchanger, and aftercooler, demonstrating consistent preventive maintenance. At 1,372 hours, wear is well within expected limits for this engine family. No evidence of overheating or fuel system contamination was found.
With modern EFI tuning and high-efficiency cooling, the Yanmar 4LHA-STP is renowned for its balance of power and longevity in sport fishing and pleasure craft. The survey results support continued service without major repair, provided routine oil, filter, and coolant maintenance is kept on schedule. The engine’s current condition suggests strong resale value and excellent operational readiness.
MARINE ENGINE SURVEY SUMMARY:
After completing the full inspection and sea trial, our professional assessment rates the engine as VERY GOOD. All systems tested within manufacturer tolerances and safety limits. No active fault codes or performance deficiencies were observed. The engine room was exceptionally clean and organized—free of oil, grease, and corrosion. Electrical routing and hose support exceeded industry norms. This result reflects the owner’s commitment to scheduled service and proper storage practices.
OVERALL ENGINE RATING: VERY GOOD — The vessel is mechanically ready for reliable operation across local and offshore routes. Continued attention to zinc anodes, coolant quality, and oil sampling is recommended to preserve longevity.
NOTICE: This survey reflects the engine’s condition as inspected on the date of report only. Marine systems can deteriorate rapidly in saltwater environments; continued maintenance is essential for safety and performance.
Owner/Surveyor: Jeff Lendall – 805 Marine Diesel Mechanic
Discuss your Yanmar 4LHA-STP marine engine or schedule a complete diesel engine inspection in Ventura, CA with our certified technicians.