Description

Komatsu D57S-1 Service Manual – 570 Pages of Factory Specs

If you’ve ever chased a fuel leak on a D57S-1 because an aftermarket manual printed the wrong injection timing, you know the cost of bad documentation. I’ve seen billable hours disappear over a half-degree timing error. That’s why I only trust the Komatsu D57S-1 Service Manual when I’ve got one of these machines on the lift. This is the same binder Komatsu dealers used – 570 pages, serial-number-specific, with judgment standards and tool lists that actually match the hardware.

Serial numbers matter on this machine. Units 6501 through 20000 use the S4D130-1 engine; 20001 and up run the S6D108-1. The manual calls out both, with separate references to the 130 Series and 108 Series engine shop manuals where needed. You don’t guess which engine you’re working on – the manual tells you exactly what to look for.

Komatsu D57S-1 Service Manual – Engine Section (10)

The engine section is where most of the heavy work lives. Section 10 splits into Testing and Adjusting (12) and Disassembly and Assembly (13). You get a Table of Judgment Standard Value right at the start – no flipping through appendices to find compression limits. The tool list is specific: which socket for the valve adjuster, which adapter for the compression gauge. Everything is written for a mechanic, not a parts counter clerk.

Valve Clearance and Compression Testing – Page 12-1

Page 12-1 kicks off the testing chapter. The valve clearance adjustment procedure is listed clearly – intake and exhaust specs, cold engine only, sequence order. I’ve seen guys jump straight to the adjustment without checking the judgment standard values first. That’s how you burn a valve. The manual also covers measuring compression pressure, with a warning to disable the fuel injection pump before cranking. Common sense? You’d be surprised how many skip it.

Fuel Injection Timing: What the Manual Says

Fuel injection timing is covered under “Testing and Adjusting Fuel Injection Timing (Delivery Method).” No generic “remove pump and align marks” nonsense. The manual walks you through static timing with the delivery method using the nozzle holder assembly. It lists the exact fuel injection pump removal steps in Section 13 – dismounting and mounting sequences with torque values for the mounting bolts. If you’ve got an aftermarket pump, you still need to set it to factory spec, not guess.

Disassembly and Assembly – 13 Steps for Major Components

Section 13 is a beast: alternator, starting motor, water pump, engine oil cooler, fuel injection pump, turbocharger, nozzle holder and prechamber, cylinder head, engine, radiator. Each component has separate dismounting and mounting procedures. The cylinder head section is worth the price alone – it gives you the head bolt tightening sequence and torque in stages. You’ll also find removal and installation instructions for the same components repeated in a different order (disassembly vs. removal). That’s not a mistake; it’s two different levels of repair. The dismounting/mounting sections assume the engine is out; the removal/installation sections are for in-frame work.

Power Train: Torqflow Transmission Hydraulic Circuit

Drop the transmission? Section 21 (Structure and Function) breaks down the entire power train: damper, universal joint, torque converter, Torqflow transmission, steering clutch hydraulic system, final drive. The Torqflow hydraulic circuit diagram is in there – no blurry photocopy, it’s the original Komatsu drawing. For those wrenching on the transmission itself, the manual covers the control valve, inching valve, and lubrication system. A quick note: if you’re ordering a replacement Manual Transmission for a different application, this one uses a Torqflow powershift – don’t confuse the two.

Test the Steering Linkage Correctly – Section 22

Section 22 covers Testing and Adjusting for the power train. The steering (brake) linkage adjustment procedure is on page 22-1 along with oil pressure and temperature measuring. The manual gives you the pressurize-and-hold test for the steering clutch and brake. You need a 0-150 psi gauge with a 1/8 NPT fitting – the tool list tells you exactly what to buy. No generic “use a pressure gauge.” It also covers adjusting the gear shift lever linkage and inching linkage. If your D57S-1 wanders or the brake pedal feels spongy, start here. For more on basic transmission types, see Manual Transmission.

Why OEM Documentation Matters

This is an original Komatsu service manual – no third-party reprint, no scanned facsimile. The page revision list on page 00-3 shows which pages were updated and when. You can see exactly what changed. Aftermarket manuals often combine multiple serial number ranges into one generic procedure, which is how you get a torque value that strips a bolt. This manual specifies torque values, judgment standards, and tool lists by serial number. That’s the difference between a fixed machine and a comeback.

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Does this manual cover both engine variants?

Yes, it covers the S4D130-1 (serial 6501-20000) and S6D108-1 (serial 20001 and up).

What is the correct procedure for adjusting valve clearance on the S6D108-1 engine?

The manual specifies intake and exhaust clearance values for a cold engine, with a specific sequence that must be followed using the timing marks on the flywheel. You need a feeler gauge and a socket for the rocker arm adjusting screw. The adjustment is done with the engine at room temperature – hot engine specs are different and not given in this section. After adjusting each valve, recheck with the feeler gauge to confirm the drag is correct. Torque the lock nut to the value listed in the judgment standard table. Failure to follow the sequence can bend a pushrod or cause the valve to hit the piston on startup.

You can pay a dealer $180 an hour to guess what the manual says, or you can own the manual yourself. If you’re tired of chasing aftermarket errors and want the same specs Komatsu put in the hands of its own technicians, Access the Factory Manual.