Part of the Yanmar Parts Manuals.
The rod caps are off, the crankpin bearings are scored, and the job stalls right there for want of one part number. This PDF is Yanmar's own parts catalog for the 3TNE78A-B1 diesel, publication Y00B5871, and its listings are how you turn a bench full of worn pieces back into an order sheet.
Seventeen sections run through the whole engine: cylinder block, cylinder head and bonnet, camshaft and driving gear, crankshaft and piston, the lubrication and cooling water systems, fuel injection pump, governor, injection pipes and nozzles, starting motor, and generator, down to the optional gasket set. Each one itemizes the assemblies and the small hardware (valve stem seals, thrust bearings, delivery valve shims) that a rebuild actually consumes.
At 36 pages and under a megabyte, it opens on anything and prints clean, so the part numbers are at the bench, or wherever the engine happens to be, when you need them.
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 |
| 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
Clogged fuel filter starves the engine
Hard starting and power that fades under load often trace back to a dirty fuel filter or a cracked line pulling air. The Fuel Oil Pipe section lists the filter, strainer, pipes, clamps, and fuel oil pump, so you can replace the whole supply path in one order.
Manual Section: Fuel Oil Pipe p. 28Worn injection pump elements cause rough running
A tired plunger and barrel or a leaking delivery valve shows up as uneven firing and a rack that hunts. The Fuel Injection Pump section breaks the pump down to plungers, barrels, delivery valves, control rack, shims, and springs, so you can order elements instead of a complete pump.
Manual Section: Fuel Injection PumpDribbling injectors smoke and knock
A nozzle that no longer seals leaves raw fuel in the cylinder, and you hear it as knock and see it as smoke. The Fuel Injection Pipe section itemizes the injection valve assemblies, nozzles, holders, springs, and shims, plus the injection pipes themselves.
Manual Section: Fuel Injection PipeGovernor hunting and surging idle
Surging at idle or under light load usually means wear in the governor linkage rather than the pump itself. The Governor section lists the links, levers, shafts, springs, weights, and O-rings individually, so the sloppy piece can be replaced on its own.
Manual Section: GovernorStarter drags or fails to engage
When the engine cranks slowly or the pinion grinds without engaging, the fault is often brushes, the clutch, or the shift lever inside the starter. The Starting Motor section lists the armature, bearings, field coil, brushes, clutch, and pinion, so a rebuild is an option instead of a whole new unit.
Manual Section: Starting MotorOverheating from cooling system wear
A stuck thermostat, a glazed or loose V-belt, or a tired water pump will push this engine hot no matter what it is powering. The Cooling Water System section covers the water pump, V-belt, fan, thermostat, thermoswitch, and cooling water pipe.
Manual Section: Cooling Water SystemBlow-by and rising oil consumption
Heavy breather fumes and oil disappearing between changes point to worn rings or crankpin bearings, and that means the engine comes apart. The Crankshaft & Piston section lists pistons with rings, piston pins, connecting rod assemblies, crankpin bearings, and the flywheel.
Manual Section: Crankshaft & PistonFrequently Asked Questions
Which engine does this parts catalog cover?
It covers the Yanmar 3TNE78A-B1 diesel engine and matches Yanmar publication number Y00B5871. It is in English and runs 36 pages. If the plate on your engine reads 3TNE78A-B1, this is the matching parts book.
Does it cover the fuel system?
Yes. The Fuel Injection Pump section lists plungers, barrels, delivery valves, control rack, shims, and springs; the Fuel Injection Pipe section covers nozzle assemblies, holders, and pipes; and the Fuel Oil Pipe section on pages 28 and 29 lists the fuel filter, strainer, pipes, and fuel oil pump. p. 28
Does it include torque specs or rebuild procedures?
No. This is a parts catalog: it identifies components and part numbers, from main bearings to valve stem seals, but it does not contain procedures, clearances, or torque values. Pair it with a service manual for the actual rebuild work.
Are internal engine parts listed for a full rebuild?
Yes. The Cylinder Block section covers main bearings, thrust bearings, and the camshaft bush; Crankshaft & Piston lists pistons with rings, piston pins, connecting rods, and crankpin bearings; Cylinder Head & Bonnet covers valves, guides, springs, and the rocker arm assembly. An optional gasket set section rounds it out.
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.
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