Part of the Yanmar Parts Manuals.
The crank is out, the micrometer says the journals need a regrind, and the next question is whether Yanmar ever cataloged undersize bearings for this engine. This catalog settles it: 0.25 undersize main and crank-pin bearings and a 0.25 oversize ring set are all listed, with the part numbers to order them.
Publication Y00B3761 is Yanmar's parts catalog for the 3TNA72L-UTB industrial diesel in its YB10-2 specification. Seventy pages in 35 sections run from the cylinder block and gear housing through the fuel injection pump, governor, starting motor, and the gasket set at the back. Every plunger, shim pack, seal, and bush has its listing, so the parts order that comes back matches the engine on your stand.
It does not matter what this engine is bolted into. As a small PDF it goes wherever the work is: on a phone at the bench, or printed and clipped up above the parts washer.
What's Inside This Yanmar 3TNA72L-UTB (YB10-2) Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Engine | 1 | - |
| Cylinder Block | 2-3 | Cylinder Block Assy, Main Bearing, Thrust Bearing, Camshaft Bush, Cylinder Head Gasket, Joint PT1, Gasket |
| Gear Housing | 4-5 | Gear Housing Assy, Gear Housing Cover, Oil Seal HTC456208, Knock Pipe, Generator Bracket |
| Gear Housing Blind Cover | 6-7 | Cover, Pump Cover Gasket, Lub. Oil Supply Cap, Hydraulic Oil Pump Cover, Blind Cover, F.feed Pump Gasket |
| Flywheel Housing | 8-9 | Flywheel Cover Cap, Bolt, Pin |
| Oil Seal Housing | 10-11 | Oil Seal, Pin, Bolt |
| Lub. Oil Sump | 12-13 | Lub. Oil Sump Assy, Oil Sump Spacer, Plug, O-Ring |
| Cylinder Head | 14-15 | Cylinder Head Assy, Suction Valve, Exhaust Valve, Valve Spring, Spring Retainer, Valve Stem Seal, Valve Cap, Nozzle Protector |
| Rocker Arm | 16-17 | Arm Support Assy, Rocker Shaft Assy, Rocker Arm Assy, Rocker Arm Support, Spring |
| Bonnet | 18-19 | Lub. Oil Supply Cap, Knob, Head Bonnet Assy, Joint, Shelter Plate, Plate Gasket, Bonnet Gasket, Pipe 12X |
| Air Cleaner | 20-21 | Case Assy, Dust Pan Assy, Retainer, Air Cleaner Element, Air Intake Pipe, Suction Pipe, Air Cleaner Support |
| Suction Manifold | 22-23 | Air Intake Manifold, Int.manifold Gasket, Bolt |
| Exhaust Manifold | 24-25 | Exhaust Manifold Gasket, Washer, Bolt |
| Camshaft | 26-27 | Bearing, Fuel Injection Pump Camshaft, Camshaft Gear, Tappet, Push Rod, Fuel Injection Pump Gear |
| Crankshaft | 28-29 | Crankshaft Assy, Crankshaft Gear, V-pulley, Key |
| Flywheel | 30-31 | Flywheel Assy, Ring Gear, Bolt, Pin |
| Piston | 32-33 | Piston w/ Rings, Ring Set, Pin, Circlip |
| Connecting Rod | 34-35 | Connecting Rod Assy, Crank-pin Bearing, Piston Pin Bush, Bolt |
| Driving Gear | 36-37 | Idle Gear Retainer, Idle Gear Shaft, Idle Gear w/ Bush, Idle Gear Bush |
| Lub. Oil Pump | 38-39 | Pump Assy, Lub. Oil, Gasket, L.O.PUMP, Bolt M 6X 20 |
| Lub. Oil System | 40-41 | Lub. Oil Dipstick, Dipstick Guide, Oil Filter Bracket, Bracket Gasket, Lub. Oil Filter, Oil Press Valve Assy, Lub. Oil Pipe Assy, Oil Pressure Switch |
| Cooling Water Pump | 42-43 | Cooling Water Pump Assy, Cooling Water Pump Gasket, V-belt, Cooling Water Pump V-pulley, V-pulley, Cooling Fan, Sub Reservoir Assy, Reservoir Tank Cap |
| Thermostat | 44-45 | Gasket, Thermometer, Thermostat Cover, Thermo.cover Gasket |
| Fuel Injection Pump | 46-47 | Fuel Injection Pump Assy, Plunger w/ Barrel, Retainer, Plunger Spring, Delivery Valve w/ Seat, Delivery Valve Spring, Delivery Valve Holder, Delivery Gasket |
| Fuel Injection Valve | 48-49 | Fuel Injection Valve Assy, Nozzle Assy.fuel Injection, Valve w/ Case Holder, Valve Spring, Seat Spring, Valve Stop Spacer |
| Fuel Strainer | 50-51 | Fuel Strainer Assy, Strainer Body Assy, Taper Valve Spring, Cock Handle, Taper Valve, Spring, Fuel Element, Retaining Ring |
| Fuel Injection Line | 52-53 | Injection Pipe Retainer, Fuel Inject Pipe, Bolt |
| Fuel Line | 54-55 | Fuel Oil Pipe, Gasket, Pipe, Feed Pump |
| Fuel Return Line | 56-57 | Fuel Over Pipe Assy, Joint, Fuel Return Pipe, Gasket |
| Governor | 58-59 | Governor Case Gasket, Governor Case Cover, Governor Weight Assy, Governor Sleeve, Governor Case, Link Color, Spacer Assy, Governor Lever Shaft |
| Control System | 60-61 | Torque Spring Assy, Lead, Wire, Nut |
| Starting Motor | 62-63 | Starter 12V- .0W, Retainer, Yoke Assy, Armature Assy, Bearing, Starter Clutch, Starter Pinion, Shaft |
| Generator | 64-65 | Plate Assy, Stator, Coupler, Collar, Pulley, Flywheel Assy, Belt Adjuster |
| Glow Plug | 66-67 | - |
| Gasket Set & Special Tool (Op) | 68-70 | Gasket Set, Cylinder Head Gasket, Pump Cover Gasket, F.feed Pump Gasket, Plate Gasket, Bonnet Gasket, Int.manifold Gasket, Silencer Gasket |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Main Bearing Undersize | 0.25 | p. 2 |
| Piston Ring Set Oversize | 0.25 | p. 32 |
| Connecting Rod Bearing Undersize | 0.25 | p. 34 |
| V-Belt Length | 36.5 FM | p. 42 |
| Governor Link Length (No Color) | 88.8 | p. 58 |
| Governor Link Length (White) | 88.6 | p. 58 |
| Governor Link Length (Red) | 89.0 | p. 58 |
Yanmar 3TNA72L-UTB (YB10-2) Common Problems This Manual Covers
Hard starting with white smoke
Long cranking and white smoke on this engine usually trace back to fouled injection nozzles. The Fuel Injection Valve section lists the complete valve assembly, nozzle assembly, holder, spring, and shim pack, so you can replace parts outright instead of gambling on a cleaned tip.
Manual Section: Fuel Injection Valve p. 48Injection pump plunger wear
Dirty fuel wears the plunger and barrel and sticks the delivery valve, showing up as rough running and lost power. The Fuel Injection Pump section breaks the pump down to the plunger with barrel, delivery valve with seat, springs, and shim packs.
Manual Section: Fuel Injection Pump p. 46Crank journals worn past limits
When the crank goes out for a regrind, this catalog confirms Yanmar lists 0.25 undersize main bearings, alongside the thrust bearings and camshaft bush in the same Cylinder Block section.
Manual Section: Cylinder Block p. 2Blow-by and rising oil consumption
Worn rings mean the bores get measured, and a rebore needs the 0.25 oversize ring set listed in the Piston section, together with pistons with rings, pins, and circlips.
Manual Section: Piston p. 32Low oil pressure warnings
Before condemning the oil pump, the pressure switch and valve are cheaper suspects. The Lub. Oil System section lists the oil filter, oil pressure valve assembly, switch, and dipstick, so you can work through the circuit part by part.
Manual Section: Lub. Oil System p. 40Overheating from cooling drive wear
A glazed V-belt or a tired water pump will cook this engine quietly under load. The Cooling Water Pump section carries the pump assembly, gasket, V-belt, V-pulley, and fan.
Manual Section: Cooling Water Pump p. 42Hunting or surging at idle
A worn governor sleeve and tired weights let the engine hunt under light load. The Governor section lists the weight assembly, sleeve, and lever assembly, and distinguishes governor links by color code so you order the correct length.
Manual Section: Governor p. 58Frequently Asked Questions
Which engine does this parts catalog cover?
The Yanmar 3TNA72L-UTB in its YB10-2 specification, a vertical multi-cylinder industrial diesel from Yanmar's T series. The publication number is Y00B3761. If the code on your engine plate matches 3TNA72L-UTB, this is the correct book regardless of what the engine is installed in.
Is this a service manual with repair procedures?
No. It is the factory parts catalog: 35 bookmarked sections from Cylinder Block through Glow Plug and the Gasket Set, each listing the parts for that assembly. Use it to identify and order the right components; pair it with a service manual for procedures and torque figures.
Does Yanmar list undersize bearings and oversize rings for this engine?
Yes. The Cylinder Block section lists 0.25 undersize main bearings, the Connecting Rod section lists 0.25 undersize crank-pin bearings, and the Piston section lists a 0.25 oversize ring set, so a reground crank or rebored block can be built back with cataloged parts. p. 32
How much of the fuel system is covered?
All of it, by section: the Fuel Injection Pump (plunger with barrel, delivery valve with seat, shim packs), Fuel Injection Valve (nozzles, holders, springs), Fuel Strainer, Fuel Injection Line, the Fuel Line with its feed pump, and the Fuel Return Line. p. 46
Is this Yanmar 3TNA72L-UTB (YB10-2) & variants Parts Catalog a digital download?
A 70-page Parts Catalog in searchable PDF format, available the moment you complete checkout. View on computer, tablet, or phone, with no shipping wait.
Can I print specific sections of this Yanmar 3TNA72L-UTB (YB10-2) & variants?
Yes. The PDF has no DRM restrictions, so print any page or section you need for your shop. Works with any standard printer.
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