Need the exact part number for your Yanmar 3TNE78A-B1? This 36-page parts catalog (OEM #Y00B5871) maps every component across 17 engine sections: cylinder block, crankshaft and piston, fuel injection pump, governor, starter motor, and generator. Inside, exploded views break each assembly into labeled components with factory part numbers and cross-references, taking you from a broken part on the floor to an order number in seconds. Component identification details are woven in throughout: the cooling circuit calls out an A-38 V-belt and a 110°C thermoswitch, so you can confirm the right replacement before you order. Stop guessing at part numbers from a worn casting or a vague description. Bookmarked by section and searchable by keyword, so you jump straight to fuel injection pipes or camshaft assembly and find your number without scrolling.
What's Inside This Yanmar 3TNE78A-B1 Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Cylinder Block | - | Block Assembly, Plugs, Main Bearings, Thrust Bearings, Camshaft Bush, Cylinder Head Bolts |
| Gear Housing | - | Flange, Oil Seal, Lubrication Oil Supply Cap, Cover, Gasket, O-Rings, Bolts |
| Flywheel HOUSING&LUB.OIL Sump | - | Flywheel Housing, Cover, Plugs, Sump Assembly, Drain Plug, Oil Seal Case |
| Cylinder Head & Bonnet | - | Head Assembly, Valve Guides, Valves (suction/exhaust), Valve Springs, Retainers, Cotters, Valve Stem Seals, Rocker Arm Assembly |
| Suction Manifold & Air Cleaner | - | Suction Manifold, Air Cleaner Assembly, Elements, Dust Pan, Wing Bolts, Air Cleaner Supports, Heater |
| Exhaust Manifold & Silencer | - | Exhaust Manifold, Gasket, Silencer, Stay, Bolts, Nuts |
| Camshaft & Driving Gear | - | Tappets, Push Rods, Camshaft Assembly, Thrust Metal, Camshaft Gear, Idle Gear, Idle Gear Bush |
| Crankshaft & Piston | - | Crankshaft Assembly, Crankshaft Gear, Flywheel, Piston w/rings, Piston Pin, Connecting Rod Assembly, Crankpin Bearings |
| LUB.OIL System | - | Lubrication Oil Pump, Dipstick, Oil Inlet Pipe, Oil Strainer, Oil Filter, Oil Pressure Switch |
| Cooling Water System | - | Water Pump, V-Belt, Fan, Thermostat, Thermoswitch, Cooling Water Pipe |
| Fuel Injection Pump | - | Plunger, Barrel, Delivery Valve, Control Rack, Shims, Springs |
| Governor | - | Links, Levers, Shafts, Springs, Weights, O-Rings, Washers, Bolts |
| Fuel Injection Pipe | - | Fuel Injection Valve Assembly, Nozzle Assembly, Nozzle Holder, Nozzle Springs, Shims, Injection Pipes |
| Fuel Oil Pipe | 28-29 | Fuel Strainer, Fuel Filter, Fuel Pipes, Clamps, Fuel Oil Pump |
| Starting Motor | - | Starter Assembly, Armature, Bearings, Field Coil, Brushes, Clutch, Pinion, Shift Lever |
| Generator | - | Assembly, Washers, Collar, Stator, Coupler, Flywheel Assembly, Adjuster |
| Gasket SET(OPTIONAL) & Tool | - | Liquid Gasket, Flex Horn |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Stud Size | M6 x 30 mm | p. 8 |
| Nut Thread | M8 x 1.0 | p. 8 |
| Thermoswitch Activation Temperature | 110 °C | p. 20 |
| V-Belt Type | A-38 | p. 20 |
| Bolt Size | M10 x 65 mm | p. 32 |
Yanmar 3TNE78A-B1 Common Problems This Manual Covers
Cannot locate the correct Yanmar 3TNE78A-B1 water pump and thermoswitch part numbers after engine overheating p. 20
Check the cooling water system parts diagram on page 20. Locate the replacement thermoswitch, noting the activation temperature is rated at 110 °C. Verify the V-belt type is A-38 to ensure the new water pump pulley matches your existing drive setup before ordering components.
Manual Section: Cooling Water SystemDifficulty sourcing exact starter assembly or internal components when the starter cranks but engine does not fire p. 32
Inspect the starter assembly breakdown in the starting motor section. Match your specific armature and pinion gear part numbers to the exploded view. Ensure the replacement mounting hardware matches the standard M10 x 65 mm bolt size found on page 32 to secure the unit.
Manual Section: Starting MotorNeed to identify exact replacement mounting hardware for a leaking exhaust manifold and blown gasket p. 8
Review the exhaust manifold and silencer parts list to find the correct gasket part number. Verify the required mounting hardware includes the M6 x 30 mm stud size shown on page 8. Cross-reference the associated M8 x 1.0 nut thread to complete the assembly order.
Manual Section: Exhaust Manifold & SilencerFrequently Asked Questions
What are the replacement specifications for the fuel filter?
The manual identifies the fuel filter as 'STRAINER ASSY, FUEL' with part number 119833-55620. This assembly is depicted in the fuel system diagrams, providing the specific part number for replacement.
What are the replacement specifications for the fuel injection pump?
The fuel injection pump is listed as 'FUEL INJECTION PUMP' with part number 719910-51370. This part number specifies the correct component for replacement in the engine's fuel system.
How do you fix cannot locate the correct Yanmar 3TNE78A-B1 water pump and thermoswitch part numbers after engine overheating?
Check the cooling water system parts diagram on page 20. Locate the replacement thermoswitch, noting the activation temperature is rated at 110 °C. Verify the V-belt type is A-38 to ensure the new water pump pulley matches your existing drive setup before ordering components.
How do you fix difficulty sourcing exact starter assembly or internal components when the starter cranks but engine does not fire?
Inspect the starter assembly breakdown in the starting motor section. Match your specific armature and pinion gear part numbers to the exploded view. Ensure the replacement mounting hardware matches the standard M10 x 65 mm bolt size found on page 32 to secure the unit.
What format is this manual in?
Instant PDF download. You get the full 36-page searchable Parts Catalog immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Can I print this manual?
Yes, print as many copies as you want, and there are no restrictions. Many mechanics print the section they need and bring it to the shop floor.
Document Quality
This document is a scanned PDF with an OCR layer, allowing you to search and copy the full text. The text quality is generally good, though some scanned portions exhibit minor blurriness or fading. Diagrams and illustrations are raster images, which are clear enough for identification, and their labels are readable. Pages are mostly clean with minimal scan artifacts and occasional slight skewing. There are no notable blank or filler pages present.
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