Part of the Yanmar Parts Manuals.
The fastest way to stall a rebuild on a Yanmar 3TN66L-(E)UB is to order the wrong bearing, because this engine turns up under several designations. This parts catalog, Yanmar publication Y00B4522, applies whether your data plate reads 3TN66L-(E)UB, 3TN66L-EUB, or 3TN66L-UB, so the part numbers you pull match the engine on your stand.
Across 35 pages it breaks the engine into part groups: cylinder block, cylinder head and bonnet, camshaft, crankshaft and piston, the lubricating oil and cooling water systems, fuel injection device, fuel pipe, governor, starting motor, generator, and the gasket set with tools. Exploded views sit beside the listings, so you count washers and O-rings instead of guessing.
At 0.65 MB the PDF rides along on a phone to the parts counter as easily as it opens on a laptop beside the bench. When the head is off and you need the valve guides and bonnet gasket identified before reassembly, the right number is a bookmark away.
What's Inside This Yanmar 3TN66L-(E)UB Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Engine Information | 1 | Cylinder Block, Gear Housing, Flywheel Housing & L.O. Sump, Cylinder Head & Bonnet, Suction & Exhaust Manifold, Camshaft & Driving Gear, Crankshaft & Piston, Lub.Oil System, Cooling Water System, Fuel Injection Device, Fuel Pipe, Governor, Starting Motor, Generator, Gasket Set & Tools |
| Cylinder Block | 2-3 | Cylinder Block Assy, Main Bearing, Thrust Bearing, Camshaft Bush, Bush, Joint PT1, Cylinder Head Gasket, Gasket |
| Flywheel Housing & L.O. Sump | 6-7 | Flywheel Housing, Flywheel Cover Cap, Lub. Oil Sump Assy, Oil Sump Spacer, Oil Seal Case Assy, Oil Seal Housing, Oil Seal |
| Cylinder Head & Bonnet | 8-10 | Bonnet Assy, Filler Cover, Joint, Breather Joint, Shelter Plate, Gasket, Bonnet Gasket, Vinyl 12X Pipe |
| Suction & Exhaust Manifold | 11-12 | Suction Manifold, Intake Manifold, Suction Manifold Gasket, Exhaust Manifold, Exhaust Manifold Gasket |
| Camshaft & Driving Gear | 13-14 | Camshaft Assy, Camshaft Gear, Thrust Bearing, Tappet, Push Rod, Fuel Cam Bearing, Fuel Injection Pump Cam Assy, Flange |
| Crankshaft & Piston | 15-16 | Crankshaft Assy, Flywheel Assy, Ring Gear, V-pulley, Piston w/ Ring, Ring Set, Connecting Rod Assy, Crankpin Bearing |
| Lub.Oil System | 17-18 | Lub. Oil Pump Assy, Lub. Oil Pump Gasket, Dipstick Guide, Dipstick, Lub. Oil Filter, Oil Press Valve Assy, Lub. Oil Inlet Pipe Assy, Oil Pressure Switch |
| Cooling Water System | 19-20 | C.w Pump Assy, Cooling Water Pump Assy, Cooling Water Pump Gasket, Cooling Water Gasket, Gasket, Cooling Water Pump V-pulley, V-belt, Fan |
| Fuel Injection Device | 21-23 | Fuel Injection Pump Assy, Plunger w/ Barrel, Retainer, Plunger Spring, Delivery Valve w/ Seat, Delivery Valve Spring, Delivery Valve Holder, Delivery Gasket |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Oil Pressure Switch Setting | 0.5KG | p. 17 |
| Governor Link Length (No Color) | 88.8 | p. 26 |
| Governor Link Length (White) | 88.6 | p. 26 |
| Governor Link Length (Red) | 89.0 | p. 26 |
| Key Size (Camshaft) | 4x12 | p. 13 |
Yanmar 3TN66L-(E)UB Common Problems This Manual Covers
Hard starting after sitting
An engine that cranks but will not fire after a layup usually points to air ingress or a clogged strainer in the fuel supply. The Fuel Pipe section lists the F.O. strainer assembly, fuel oil pipes, and pipes with joints, so you can replace the leak path instead of bleeding it over and over.
Manual Section: Fuel Pipe p. 24Low oil pressure warning
Oil pressure faults on a small diesel come down to the pump, the relief valve, or a lying switch. This section lists the lub. oil pump assembly, the oil pressure valve assembly, the lub. oil filter, and the oil pressure switch with its 0.5 kg setting.
Manual Section: Lub.Oil System p. 17Overheating under load
Thermostats and water pumps are routine wear items on the 3TN series, and an overheating engine rarely announces which one gave up. This section breaks out the C.W. pump assembly and gasket, V-pulley, fan, thermostat, and thermostat cover for a complete cooling-side refresh.
Manual Section: Cooling Water System p. 19Rough running from injection wear
Worn plungers and delivery valves let a diesel hunt, smoke, and lose power long before it quits. The Fuel Injection Device section itemizes the injection pump assembly down to the plunger with barrel, delivery valve with seat, delivery valve holder, and rack.
Manual Section: Fuel Injection Device p. 21Surging or unstable idle
Hunting at idle often traces to the mechanical governor: worn weights, sleeve, or linkage. This section lists the driving set, weight assembly, sleeve, shaft, and levers, and identifies the color-coded governor links by length so you order the correct one for your engine.
Manual Section: Governor p. 26Blow-by and oil consumption
Rising blow-by and a smoking breather mean rings and bores are due. The Crankshaft & Piston section lists the piston with ring, piston pin, connecting rod assembly, and crankpin bearings, so the whole bottom-end order goes in as one list.
Manual Section: Crankshaft & Piston p. 15Starter clicks but will not crank
Starter faults on these engines usually land on the magnetic switch or the pinion drive. The Starting Motor section breaks the starter into its magnetic switch, rear cover assembly, pinion assembly, and shift lever kit, so you can repair the unit instead of replacing it outright.
Manual Section: Starting Motor p. 29Frequently Asked Questions
Which Yanmar engine models does this parts catalog cover?
It is Yanmar publication Y00B4522 for the 3TN66L-(E)UB engine, and the same listings apply to the 3TN66L-EUB and 3TN66L-UB designations you may see on paperwork or data plates. It covers the engine itself, whatever equipment that engine happens to be installed in.
Is this a service manual with torque specs and clearances?
No. This is a parts catalog: exploded views, part numbers, names, and quantities for every group from cylinder block to gasket set. Use it to identify and order components during a teardown; rebuild clearances and cylinder head torque sequences belong in a separate service manual.
Does it include a complete gasket and seal listing?
Yes. The Gasket Set & Tools section lists the full gasket set along with individual items such as valve stem seals, the bonnet gasket, and the C.W. pump gasket, which is exactly what you need to order while the engine is apart for reassembly. p. 33
Can I look up fuel injection pump components?
The Fuel Injection Device section itemizes the injection pump assembly, including the plunger with barrel, delivery valve with seat, delivery valve holder, and rack, and the neighboring Fuel Pipe section covers the F.O. strainer assembly and fuel oil lines. p. 21
How will I receive this Yanmar 3TN66L-(E)UB Parts Catalog?
A 35-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 3TN66L-(E)UB Parts Catalog?
The PDF is DRM-free. Print whatever sections you need to take out to the shop. Standard letter or A4 paper works.
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