Part of the Yanmar Parts Manuals.
This 34-page Yanmar 3TNA72L-UBA parts catalog pdf (OEM #Y00B4102) breaks down the complete cylinder block, fuel injection device, and governor assemblies for your 3TNA72L-UBA/B engine. Inside, you get detailed exploded view diagrams paired with factory part numbers for every single component, from the flywheel housing to the starting motor. Open to the fuel system section to find clear illustrations of the delivery valves, plungers, and complete fuel feed pump breakdowns, making component identification fast and accurate. Verify your main bearing undersize at 0.25 before submitting an order, and confirm you need the 36.5 V-belt for the cooling water pump assembly. Stop buying the wrong replacement parts based on internet guesswork. Grab this bookmarked file, pull up the exact schematic on your phone in the shop, and get your parts order right the first time.
What's Inside This Yanmar 3TNA72L-UBA, 3TNA72L-UBA/B Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Engine | 1-2 | Cylinder Block Assy, Main Bearing, Thrust Bearing, Camshaft Bush, Cylinder Head Gasket, Gasket, Joint PT1 |
| Cylinder Block | 3-4 | Gear Housing Assy, Housing Cover Assy, Oil Seal HTC456208, Knock Pipe, Cover, Pump Cover Gasket, Gasket, Lub. Oil Supply Cap |
| Gear Housing | 5-6 | Lub. Oil Sump Assy, Oil Sump Spacer, Oil Seal Case Assy, Oil Seal, Flywheel Housing, Flywheel Cover Cap |
| Flywheel Housing & Oil Sump | 7-8 | Cylinder Head Assy, Suction Valve, Exhaust Valve, Valve Spring, Spring Retainer, Valve Stem Seal, Valve Cap, Nozzle Protector |
| Cylinder Head & Bonnet | 9-10 | Air Cleaner Support, Support Felt, Air Cleaner, Case, Air Cleaner Element, Dust Pan, Retainer, Air Intake Pipe |
| Suction Manifold & Air Cleaner | 11-12 | Silencer Gasket, Gasket, Silencer, Silencer Stay, Exhaust Manifold, Exhaust Manifold Gasket |
| Exhaust Manifold & Silencer | 13-14 | Camshaft Assy, Camshaft Gear, Thrust Bearing, Push Rod, Tappet, Fuel Cam Bearing, Fuel Injection Pump Cam Assy, Idle Gear Retainer |
| Camshaft & Driving Gear | 15-16 | Crankshaft Assy, Crankshaft Gear, Crankgear, V-pulley, Flywheel Assy, Ring Gear, Piston w/ Rings, Ring Set |
| Crankshaft & Piston | 17-18 | Lub. Oil Pump Assy, Lub. Oil Pump Gasket, Lub. Oil Dipstick, Dipstick Guide, Oil Filter Bracket, Bracket Gasket, Gasket, Lub. Oil Filter |
| Lubrication Oil System | 19-20 | Cooling Water Pump Assy, Cw Pump Assy, Cooling Water Pump Gasket, V-belt, Cooling Water Pump V-pulley, Thermo Switch, Gasket, Thermostat Cover |
| Cooling Water System | 21-22 | Fuel Injection Pump Assy, Plunger w/ Barrel, Retainer, Plunger Spring, Delivery Valve w/ Seat, Delivery Valve Spring, Delivery Valve Holder, Delivery Gasket |
| Fuel Injection Device | 23-24 | F.feed Pump Gasket, Gasket, Feed Pump, Fuel Feed Pump Assy, F.o Strainer Assy, Taper Valve, Taper Valve Spring, Lever |
| Fuel Pipe | 25-26 | Governor Case, Governor Case Gasket, Gasket, Governor Case Cover, Link Color, Link, Governor Weight Assy, Governor Sleeve |
| Governor | 27-28 | Starter 12V- .0W, Retainer, Yoke Assy, Armature Assy, Bearing, Starter Clutch, Starter Pinion, Shaft |
| Starting Motor | 29-30 | Generator, Collar, Plate Assy, Stator, Coupler, Flywheel Assy, Belt Adjuster |
| Generator | 31-32 | Flex Horn, Gasket Set, Cylinder Head Gasket, Bonnet Gasket, Int.manifold Gasket, Silencer Gasket, Exhaust Manifold Gasket, Cooling Water Pump Gasket |
| Tool & Gasket Set Optional | 33-34 | Overview, Parts List, Brush, Gasket, Liquid, Cylinder Head, Rocker Cover, Oil Pan |
Every system also includes overview.
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Main Bearing Undersize | 0.25 (unit not specified) | p. 2 |
| Piston W/Ring Oversize | 0.25 (unit not specified) | p. 16 |
| Ring Set Oversize | 0.25 (unit not specified) | p. 16 |
| Bearing Pin Undersize | 0.25 (unit not specified) | p. 16 |
| V-Belt FM Length | 36.5 (unit not specified) | p. 20 |
| Fuel Pipe Diameter x Length | 12mm x 400mm | p. 24 |
| Governor Link Length (No Color) | 88.8 (unit not specified) | p. 26 |
| Governor Link Length (White) | 88.6 (unit not specified) | p. 26 |
| Starter Motor Rating | 12V-1.0W | p. 28 |
Yanmar 3TNA72L-UBA, 3TNA72L-UBA/B Common Problems This Manual Covers
Yanmar 3TNA72L-UBA engine starts poorly or will not crank over in cold weather conditions p. 29
Check the exploded view on page 29 for the starting motor components. Locate the 12V-1.0W starter assembly specification on page 28 to find the correct replacement part number. Verify the armature assembly and magnetic switch match your specific serial number block.
Manual Section: Starting MotorEngine overheats rapidly under load and the temperature gauge fluctuates wildly during normal operation p. 21
Inspect the cooling water system parts diagram on page 21. Find the exact part number for the V-belt, ensuring you select the one with a 36.5 length specification from page 20. Cross-reference the water pump assembly and gasket numbers before ordering replacement parts.
Manual Section: Cooling Water SystemSevere metal debris in the oil pan and low compression across all engine cylinders p. 17
Review the crankshaft and piston parts list on page 17. Identify the correct part numbers for the 0.25 oversize piston with rings listed on page 16. Match the connecting rod bearings and piston pins precisely to your engine series to ensure proper clearances.
Manual Section: Crankshaft & PistonEngine surges at idle or fails to maintain a steady RPM under changing loads p. 27
Examine the governor parts breakdown on page 27. Find the specific part number for the governor link, noting the 88.8 length specification from page 26 for the uncolored variant. Check the adjacent governor weight assembly and spring part numbers to complete your order list.
Manual Section: GovernorFrequently Asked Questions
How do you fix 3TNA72L-UBA engine starts poorly or will not crank over in cold weather conditions?
Check the exploded view on page 29 for the starting motor components. Locate the 12V-1.0W starter assembly specification on page 28 to find the correct replacement part number. Verify the armature assembly and magnetic switch match your specific serial number block.
How do you fix engine overheats rapidly under load and the temperature gauge fluctuates wildly during normal operation?
Inspect the cooling water system parts diagram on page 21. Find the exact part number for the V-belt, ensuring you select the one with a 36.5 length specification from page 20. Cross-reference the water pump assembly and gasket numbers before ordering replacement parts.
How do you fix severe metal debris in the oil pan and low compression across all engine cylinders?
Review the crankshaft and piston parts list on page 17. Identify the correct part numbers for the 0.25 oversize piston with rings listed on page 16. Match the connecting rod bearings and piston pins precisely to your engine series to ensure proper clearances.
How do you fix engine surges at idle or fails to maintain a steady RPM under changing loads?
Examine the governor parts breakdown on page 27. Find the specific part number for the governor link, noting the 88.8 length specification from page 26 for the uncolored variant. Check the adjacent governor weight assembly and spring part numbers to complete your order list.
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