Yanmar YM series diesel engines are the top choice for boat owners with small vessels, sailboats, and pleasure crafts. The integration of common rail fuel injection into lightweight applications makes these engines a source of clean and energy-efficient powering solution for propulsion systems. Despite the cutting-edge features, Yanmar engines require regular scheduled maintenance to achieve higher fuel efficiency and optimal performance. With a smart engine care regimen and on-time parts replacement with genuine items, vessel owners can enjoy an extended engine lifecycle, too.
In this blog post, we are offering everything you need to keep your Yanmar 3YM20 engines running in perfect condition for years. From a compatible spare parts list to troubleshooting tips, this article has all the information for vessel operators and technicians to take good care of Yanmar diesel engines.
Yanmar 3YM20 Marine Engine – An Overview
Yanmar 3YM20 is a robust diesel engine featuring a revolutionary three-cylinder block configuration. This 29HP engine offers a powerful 15.3 kW / 21 mhp rated output at 3600rpm and a displacement of 0.854 L / 52.1 cu. In. The in-line pump integration and common rail indirect injection combustion system make these engines ideal for achieving clean and noiseless operation even at higher torque—all in all, a fabulous powering solution for small pleasure crafts and sailboats. With a decent 2.4-2.7L oil capacity, the module is one of the best in high-output diesel engine technology. Stay safe with an eco-friendly model with RCD 2, EPA Tier 3, EPA Tier 3C, and BSO II EMC certification.
OEM Yanmar Spare Parts for 3YM20 Marine Engines
Timely maintenance is crucial for achieving optimal engine efficiency in Yanmar-powered vessels. The process also involves changing the worn-out and faulty parts with genuine items. Yanmar manufactures spare parts for its entire engine lineup. Choose Yanmar replacement parts by OEM part number to achieve the same output as delivered by the original components.
If you want to upgrade to a Yanmar 3YM20 diesel engine, it is highly recommended to keep the following spare parts handy. Regular maintenance and timely replacement of parts offer vessel safety and an extended engine lifecycle. Here is a list of original compatible spare parts for Yanmar 3YM20 engines.
Filters Components
Oil Filter (119305-35170)
Fuel Filter Element (104500-55710)
Air Filter Element (128270-12540 or 128170-12540 depending on version)
Cooling & Impellers
Impeller (128990-42200)
Yanmar Ready-Mixed Coolant (Pink) (COOLANT-PRO-5L)
Engine Components & Gaskets
Exhaust Mixing Elbow (L-type) (128370-13600)
Exhaust Manifold Gasket (104211-13201)
Cylinder Head Assembly (728170-11700)
Valve Stem Seal (124950-11340)
Packing, Pre-combustion Chamber (101204-11452)
Sensors & Electrical Systems
Oil Pressure Switch (124060-39452)
Electric Stop Solenoid (119653-77950)
Alternator & Belts
V-Belt for Alternator (A37.5) – (119831-42290)
Alternator (12V–125A) – (128990-77250)
Belt Cover Assembly – (128990-77460)
Alternator Drive Belt (119831-42290E)
Serpentine Belt (128790-77580)
Timing Belt (119771-00201)
Drive Belt for Seawater Pump (104511-78780)
Exhaust Components
Silencer Assembly – 128990-12500
Exhaust Mixing Elbow (L-type) – 128370-13600 (Elbow Assembly, mixing)
Gasket, Exhaust Manifold – 119717-13110
Engine Lubrication (Oil System)
Oil Filter Assembly (D68xL65) – 119305-35170
O-Ring, P15.0 – 119717-32060
Oil Inlet Pipe Assembly – 128890-35080
Oil Pressure Switch (hydraulic switch) – 114250-39450
Water & Cooling System
Fresh-Water Pump Assembly – 119540-42000
Seawater Pump V-Belt (M/19) – 104511-78780
Impeller Kit (Seawater Pump) – 128990-42570
Wear Kit (Seawater Pump) – 128990-42550
Water Cooler Assembly (Fresh-Water) – 128990-44900
Miscellaneous
Engine Stop Cable (104271-67550)
Oil Drain Connector (196311-92960)
Expansion Tank (fresh-water cooling) (OEM fit)
Flexible Engine Mounts (OEM fit)
B20 Control Panel (164100-30100)
Belt Cover Assembly – (128990-77460)
Air Intake Silencer Element – (128270-12540)
Yanmar Expansion Tank Parts for Fresh Water Cooler
Tank Assembly, Expansion – 748999-44260
Tank Assembly, Expansion – 148999-44050
Plug, M36×2 – 148620-01091
Cover – 153605-11720
Gasket, Tank Cover – 153605-11731
Gasket, 36×1.0 – 23414-360000
Bolt, M8×20 Plated – 26106-080202
Liner, Cylinder – 148960-44500
Filler Assembly – 126677-44600
Filler Assembly – 128623-44210
Gasket – 126650-44610
Bolt, M8×16 Plated – 26106-080162
Gauge, Level – 146613-44900
Bolt – 146613-4490C
O-Ring – 146613-4490D
O-Ring – 146613-4490E
Cock Assembly, 1/4 – 119620-49290
Washer, 12 – 22137-120000
Bolt, M12×60 Plated – 26116-120602
Bolt, M12×115 Plated – 26116-121152
Support – 148960-49370
Bolt, M12×25 Plated – 26116-120252
Bolt, M12×30 Plated – 26116-120302
Plug, Blind – 41649-000130
Plug, M36×1.5 – 127610-44900
Washer, Seal 36 – 22190-360002
Troubleshooting Tips for Yanmar 3YM20 Marine Engines
Problem 1 – The Engine does not start immediately after changing the fuel filter.
Probable reason and solution – Presence of air bubbles within the filter bracket. Bleed the filtration system to start the operations.
Things You Will Need
- 10mm/12mm spanners
- Nitrile gloves
- Rags
- Catch tray
Stepwise Guide
- Fill the primary (Racor) to the full level.
- Open the Fuel tank shutoff.
- Half-turn the bleed screw of the secondary filter of the engine.
- Work with the priming lever on the mechanical pump until the air bubbles escape from the fuel filter.
- Crack all the injector line nuts ½ turned at the injector. Give a burst for 10 seconds until the fuel spurts appear on each line. Now tighten the injector line nuts.
- Set the throttle to ~½. Preheating may be required if it is already fitted. Now start the system to hear a blip. The blip should be sufficient to remove the traces of remaining air bubbles.
Problem 2 – Wrong reading or dead Tachometer
Probable reason and solution – Find the W/stator signal at the alternator
Things You Will Need
- Wiring diagram/chart
- Contact cleaner
- Multimeter with (Hz) frequency
Stepwise Guide
- Locate the tack signal wire marked W/Y/P at the alternator
- Clean and tighten the spade/ring
- Run the engine to take the AC measurement
- Measure the AC on the tach lead to the engine ground.
Problem 3 – Engine Overheating at Higher RPM
Probable reason and solution – Faulty impeller replacement is required
Things You Will Need
- Screwdrivers
- Pliers
- New impeller
- Cover O-ring
- Belt
- Bucket
Stepwise Guide
- Open the seacock to check the seawater
- Clean the seawater strainer
- Pull the cover of the raw water pump
- Use a puller and pliers to remove the impeller
- Remove the hose connected to the heat exchanger inlet
- Clean the traces of chipped rubber particles on the exchanger
- If the vanes are missing, install the new ones after applying glycerine
- Remove the worn-out o-rings and replace them with new ones
Note: The Yanmar OEM impeller kit includes glycerine, O-rings, and replacement vanes.
Only genuine spare parts are good enough to keep your Yanmar-operated sailboats cruising without any glitches. Alfa Marine Spare Parts is your ultimate destination to purchase genuine Yanmar marine engines, accessories, and spares at affordable prices. Contact us today to procure OEM spare parts from the world’s best marine engine brands – Cat, Cummins, Deutz, Detroit Diesel, Perkins, Scania, Wartsila, and others.
