Part of the Yanmar Parts Manuals.
From the cylinder block casting to the starting motor pinion, this Yanmar parts catalog (publication Y00B5881) breaks the 3TNA72L-UBA and 3TNA72L-UBB down into sixteen exploded sections, one system per spread: Crankshaft & Piston, Fuel Injection Device, Governor, Lub. Oil System, Cooling Water System, and the rest.
Anyone who has tried to order bearings or a delivery valve for a small Yanmar triple by guesswork knows how that ends: the wrong part in the mailbox and the engine still apart on the stand. This catalog pins each component to its factory part number, so the head gasket, thermostat, or injection nozzle you order is the one built for this engine, whichever equipment it happens to live in.
It is a 34-page bookmarked PDF, 0.55 MB, in English. Download it once, print the pages you need, and it is yours for the life of the rebuild.
What's Inside This Yanmar 3TNA72L-UBA, 3TNA72L-UBB, 3TNA72L-UBA/UBB Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Cylinder Block | 3-4 | Gear Housing Assy, Housing Cover Assy, Oil Seal HTC456208, Knock Pipe, Cover, Gasket, Lub. Oil Supply Cap, Blind Cover |
| Gear Housing | 5-6 | Lub. Oil Sump Assy, Oil Sump Spacer, Oil Seal Case Assy, Oil Seal, Flywheel Housing, Flywheel Cover Cap |
| Flywheel Housing & Lub. 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 |
| Suc. Manifold & Air Cleaner | 11-12 | Gasket, Silencer, Silencer Stay, Exhaust Manifold, Exhaust Manifold Gasket |
| Exh. 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, Crankgear, V-Pulley, Flywheel Assy, Ring Gear, Piston W/ Rings, Ring Set, Piston W/ Ring |
| Crankshaft & Piston | 17-18 | Lub. Oil Pump Assy, Lub. Oil Pump Gasket, Lub. Oil Dipstick, Dipstick Guide, Oil Filter Bracket, Gasket, Lub. Oil Filter, Oil Press Valve Assy |
| Lub. Oil System | 19-20 | Cooling Water Pump Assy, Cooling Water Pump Gasket, V-Belt, Cooling Water Pump V-Pulley, Thermo Switch, Gasket, Thermostat Cover, Thermostat |
| 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 | Gasket, Fuel Feed Pump Assy, F.o Strainer Assy, Taper Valve, Taper Valve Spring, Lever, Strainer Cup, Retaining Ring |
| Fuel Pipe | 25-26 | Governor Case, Gasket, Governor Case Cover, Link Color, Link, Governor Weight Assy, Governor Sleeve, Spacer Assy |
| 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, Bonnet Gasket, Exhaust Manifold Gasket, Cooling Water Pump Gasket, Liquid Gasket |
| Gasket Set (Optional) & Tool | 33-34 | Flex Horn, Gasket SET(NON-ASB.), Gasket, Bonnet, O-Ring, EXH.MANIFOLD |
Yanmar 3TNA72L-UBA, 3TNA72L-UBB, 3TNA72L-UBA/UBB Common Problems This Manual Covers
Hard starting after sitting
Stale fuel, a clogged strainer, or air pulled in at a loose pipe joint will leave this engine cranking without firing. The Fuel Pipe section diagrams the fuel feed pump, strainer assembly, and every pipe and fitting between tank and injection pump so you can replace the leak point instead of chasing it.
Manual Section: Fuel Pipe p. 25White smoke and rough running
Worn injection nozzles and plungers make a small diesel smoke, knock, and lose power. The Fuel Injection Device section itemizes the injection pump assembly, plunger with barrel, delivery valve, and nozzle assemblies so you can order exact replacements rather than rebuilding around mystery parts.
Manual Section: Fuel Injection Device p. 23Slow cranking or starter grinding
Slow, inconsistent cranking often ends at the starter itself once wiring and battery check out. The Starting Motor section breaks the 12V starter into yoke, armature, clutch, pinion, and housing, so you can replace one worn piece instead of the whole unit.
Manual Section: Starting Motor p. 29Overheating or coolant temperature creeping up
A tired coolant pump, a stuck thermostat, or a glazed V-belt will push the temperature up long before anything seizes. The Cooling Water System section lists the pump assembly, thermostat, thermo switch, V-belt, and pulley with their part numbers.
Manual Section: Cooling Water System p. 21Low oil pressure warnings
Low pressure at operating temperature points to the oil pump, a bypassing filter, or a sticking pressure valve, and none of those are parts to guess at. The Lub. Oil System section covers the pump assembly, filter, oil pressure valve, and dipstick.
Manual Section: Lub. Oil System p. 19Hunting or surging engine speed
When the engine hunts at idle or surges under load, worn governor linkage and weights are the usual suspects. The Governor section diagrams the case, link, weight assembly, shaft, and lever so you can see how the mechanism assembles and which pieces to renew.
Manual Section: Governor p. 27Oil leaks after reassembly
Reusing crushed gaskets and hardened O-rings is how a fresh rebuild ends up dripping on the bench. The Gasket Set (Optional) & Tool section lists the non-asbestos gasket set, bonnet gasket, exhaust manifold gasket, and O-rings so the engine goes back together sealed.
Manual Section: Gasket Set (Optional) & Tool p. 33Frequently Asked Questions
Which Yanmar engines does this parts catalog cover?
It covers the Yanmar 3TNA72L-UBA and 3TNA72L-UBB three-cylinder diesel engines, Yanmar publication Y00B5881. Both variant suffixes are covered in the same catalog, and it distinguishes them where it matters: the governor link is listed in three lengths by colour code on page 26 — 88.8 mm unmarked, 88.6 mm white, 89.0 mm red — so you order the one your engine actually carries.
Is this a service manual with torque specs and procedures?
No, this is the factory parts catalog: exploded diagrams and part numbers for every system from the Cylinder Block through the Starting Motor and Generator. Use it to identify and order the right components; pair it with a service manual when you need rebuild procedures.
Does it list rebuild-grade parts like oversize pistons?
Yes. The Crankshaft & Piston section lists oversize piston and ring sets for rebored cylinders, and undersize main bearings appear with the Cylinder Block parts, so after machining you can order the correct oversize or undersize components by part number. p. 17
Which cooling system parts can I identify with it?
The Cooling Water System section diagrams the coolant pump assembly, thermostat, thermo switch, V-belt, and V-pulley, each with its Yanmar part number. If the engine runs hot, every replaceable cooling component is identified there. p. 21
What format is this 3TNA72L-UBA manual in?
Immediate download of the complete 34-page searchable Parts Catalog. Access it on any device, from a laptop at your desk to a phone in the field.
Am I able to print pages from this 3TNA72L-UBA?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
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