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 Yanmar 4TNC88L-RB, B50-2 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 |
Yanmar 4TNC88L-RB, B50-2 Common Problems This Manual Covers
Low Compression and Oil Burning
Worn rings and bores show up as blow-by, oil consumption and hard cold starts, and the fix is a proper top-end and bottom-end rebuild. The Crankshaft & Piston section identifies pistons, rings and bearings by number, including the 0.25 oversize ring sets listed for rebored engines.
Manual Section: Crankshaft & PistonFuel Injection Pump Wear
Uneven running, hard starting and loss of power on an aging diesel often trace back to worn plungers and delivery valves. The Fuel Injection Pump section breaks the pump down into camshaft, plunger, delivery valve, control rack and fuel feed pump so you can order the exact wear parts.
Manual Section: Fuel Injection Pump p. 22Overheating and Cooling System Failures
A chafed hose or tired cooling components can cook this engine before the gauge tells the whole story, and a cracked head is an expensive way to find out. The Cooling Water System section identifies every replacement part by number so worn items go on the bench, not back in service.
Manual Section: Cooling Water SystemOil Leaks From Aged Seals
Once one gasket weeps, the rest of the same vintage are usually close behind, and resealing piecemeal means repeat teardowns. The Gasket Set (Optional) & Tool section lists the cylinder head gasket, valve stem seals, fuel injection pump O-ring and liquid gasket as a set for a full reseal.
Manual Section: Gasket Set (Optional) & Tool p. 37Clogged Air Cleaner Starving the Engine
Dust load in the intake shows as black smoke and falling power, and running a collapsed element will dust the bores. This section lists the element, element retainer, dust pan and air intake manifold parts so the whole intake path can be put right.
Manual Section: Suction Manifold & Air Cleaner p. 10Exhaust Leaks at the Manifold
Broken studs and blown manifold gaskets announce themselves with ticking under load and soot tracks on the head. The Exhaust Manifold & Silencer section lists the gaskets, studs, nuts and silencer parts needed to seal the system properly instead of reusing crushed hardware.
Manual Section: Exhaust Manifold & Silencer p. 12Surging or Unstable Idle
Hunting at idle on a mechanically governed diesel often comes down to wear in the governor components rather than fuel delivery itself. The Governor section identifies each part by number so you replace the worn piece instead of guessing at the whole assembly.
Manual Section: GovernorFrequently Asked Questions
Which engine does this parts catalog cover?
It covers the Yanmar 4TNC88L-RB diesel engine, factory publication Y00B4721, as supplied for the B50-2. Sections run from Cylinder Block, Gear Housing and Cylinder Head through Fuel Injection Pump, Governor, Starting Motor, Generator and the optional Gasket Set & Tool listing.
Is this a workshop manual with repair procedures?
No. This is a factory parts catalog: it identifies components and their Yanmar part numbers rather than giving disassembly steps or torque procedures. It does list service sizes, such as 0.25 undersize main bearings and 0.25 oversize ring sets, so you can order correctly for a rebuild.
Does it break down the fuel injection pump?
Yes. The Fuel Injection Pump section, starting on page 22, itemizes the pump, its camshaft, plunger, delivery valve, control rack and fuel feed pump, so individual wear parts can be identified and ordered by number.
Are gaskets and seals listed as a complete set?
Yes. The Gasket Set (Optional) & Tool section on page 37 lists the optional set, including the cylinder head gasket, valve stem seals, fuel injection pump O-ring, hydraulic oil pump gasket and liquid gasket, which covers a full reseal during overhaul. p. 37
What exactly do I receive with this Yanmar 4TNC88L-RB Parts Catalog?
Instant PDF download. You get the full 39-page searchable Parts Catalog immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Am I able to print pages from this manual?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
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