Part of the Yanmar Parts Manuals.
The crank is out of a 4TNC88L-RB on the stand, the journals are back from the grinder, and the question is not how to measure them, it is which bearing set Yanmar actually supplies. Guess at that number and you wait a week for a part that does not fit. This factory parts catalog (Yanmar publication Y00B4721) settles it, covering the 4TNC88L-RB engine as supplied for the B50-2, from cylinder block, crankshaft and piston through the fuel injection pump, governor, cooling water system, starting motor and generator.
All 39 pages arrive as a small PDF download, bookmarked by section, so you can move straight from the lubricating oil system to the optional gasket set listing. It identifies every part by its Yanmar number before you order, including the 0.25 undersize main bearings and 0.25 oversize ring sets the tables call out for reground and rebored engines.
What's Inside This Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Engine 4TNC88L-RB | 1-2 | Cylinder Block, Gear Housing, Flywheel Housing & Lub. Oil Sump, Cylinder Head & Bonnet, Suc. Manifold & Air Cleaner, Exh. Manifold & Silencer, Camshaft & Driving Gear, Crankshaft & Piston, Lub. Oil System, Cooling Water System, Fuel Injection Pump, Fuel Injection Pipe, Fuel Pipe, Governor, Engine Stop Device, Starting Motor, Generator, Gasket Set (Optional) & Tool |
| Suction Manifold & Air Cleaner | 10-11 | Silencer, Air Cleaner, Dust Pan, Element Retainer, Air Intake Manifold, Heater |
| Exhaust Manifold & Silencer | 12-13 | Gasket, Silencer, Silencer Stay, Exhaust Manifold, Nut, Stud |
| Fuel Injection Pump | 22-24 | Pump, Camshaft, Plunger, Delivery Valve, Control Rack, Fuel Feed Pump |
| Gasket Set (Optional) & Tool | 37-39 | Cylinder Head Gasket, Hydraulic Oil Pump Gasket, Fuel Injection Pump O-Ring, Valve Stem Seal, Liquid Gasket, Brush |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Piston Ring Oversize | 0.25 | p. 16 |
| Ring Set Oversize | 0.25 | p. 16 |
| Main Bearing Undersize | 0.25 | p. 2 |
| Bearing Thrust Oversize | 0.25 | p. 2 |
| Thrust Bearing Oversize | 0.25 | p. 2 |
| Gear Housing O-Ring Size | P-16.0 | p. 4 |
| Flywheel Housing Drain Plug Size | M22 | p. 6 |
| Cylinder Head Stud Size | M6x20 | p. 8 |
| Air Cleaner Clamp Size | 60 | p. 10 |
