Description

Komatsu D455A-1 1988 Workshop Manual

If you’re turning wrenches on a Komatsu D455A-1, you already know this isn’t a small job. That machine weighs over 60 tons, and guessing on a torque spec or skipping a step on the engine can cost you a weekend and a pile of broken parts. I’ve seen guys try to use a Chilton’s or a third-party PDF for these dozers, and that’s how you end up with a stripped cylinder head bolt or a PTO that leaks oil from the wrong gasket. What you need is the actual Komatsu D455A-1 1988 Workshop Manual – the same book the factory techs used when these machines were new. 1202 pages, OEM prints, and all the revision updates included. There’s no substitute for that.

1202 Pages of OEM Data – Not Aftermarket Guesswork

This manual came from Komatsu’s own press in Japan, printed in December 1988. It covers serial numbers 1013 and up. The revision table inside shows that Komatsu kept updating it – pages marked with revision symbols and multiple revision numbers (⑤, ④, ③ etc.). That means you’re getting the corrections and updates, not some dump of the first edition. I’ve seen aftermarket manuals that claim to cover this model but they skip the oil cooler fan drive section for machines after serial 1301. This original has it. You want a manual that lists revised pages and tells you exactly which pages to replace? That’s a factory document.

Engine Overhaul: What This Manual Covers

The engine section (Chassis Related) breaks down into three sub-sections: 11 Structure and Function, 12 Testing and Adjusting, and 13 Disassembly and Assembly. Start with section 11 to understand the engine mounting, the radiator, the P.T.O. (power take-off), and the oil cooler fan drive system – including the pump and motor for serials 1301 and up. Fuel piping diagrams, engine control cable routing, and ether starting control are all drawn out. Then hit section 12 for testing procedures. Page 12-1 kicks off the testing and adjusting chapter – you’ll get compression checks, boost pressure specs, and temperature limits. Section 13 is where you’ll live if you’re pulling the engine. It starts with Torque Specifications for Nuts and Bolts on page 13-1. That’s not a generic chart – it’s specific to the D455A-1’s engine, covering every bolt from the fan belt tensioner to the cylinder head. Need the torque for the P.T. pump mounting bolts? It’s in there.

3 Major Systems Beyond the Engine

The Power Train section alone is bigger than most aftermarket books. It covers the torque converter, the Torqflow transmission, transfer case, steering controls, and brakes. You get hydraulic circuit diagrams for the steering brake system – separate versions for serials 1013-1500 and 1501-up. The center clutch control valve, the steering pump, the brake booster – all thoroughly documented. If you’re troubleshooting a counterrotation control problem or a brake that doesn’t release, the manual gives you the hydraulic system diagrams and the component disassembly steps. I’ve used these diagrams to trace a steering circuit leak in under an hour. Without them, you’d be tracing hoses blind.

What Torque Values Are Listed? (Don’t Guess on Fasteners)

Torque specs live in section 13, page 13-1, as I mentioned. But the manual also gives torque values throughout the disassembly/assembly procedures. When you’re mounting the cylinder head, you get a sequence and a torque value. When you install the turbocharger, there’s a torque for the mounting nuts. This is critical on an engine that sees high heat and vibration. Using the wrong torque on a water pump bolt can crack the housing. Komatsu’s specs are in both Nm and lb-ft – but I always convert to Imperial for my shop. This manual makes that straightforward because the values are printed in both units.

Does This Manual Cover the Fuel System?

Yes. The ENGINE section includes FUEL PIPING DIAGRAM, which shows the lines from the tank through the filters to the P.T. pump (full name: P.T.PUMP, dismounting and mounting procedures included). There’s also an ETHER STARTING CONTROL section for cold-weather starts. If you’re dealing with a fuel leak or a pump that won’t prime, the manual’s structure and function pages explain the flow path. You won’t find a step-by-step injection pump rebuild in this manual – that’s typically a separate pump manual – but the removal and installation steps are here. That’s enough to do the swap correctly.

Avoid Aftermarket Pitfalls – Why OEM Matters

Aftermarket print shops often copy a 1987 manual and label it as covering a 1988 model. But this manual includes revision pages through the 1988 print run – see the list of revised pages on pages 00-2 through 00-2-6. They’ll sell you a basic manual that says ‘covers D455A-1’ but omits the oil cooler fan drive updates for later serial numbers. That’s a problem when you’re working on a machine built in 1990 with serial 1501. The OEM manual from AutoRepairManuals is a direct scan of the original binder, not a reworked PDF. It’s the same quality as what I keep in my shop’s cabinet.

Related manuals you might need: Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual for wheel loaders, and Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual if you service those smaller machines. For a heavy dozer like this, nothing beats the original.

One more thing – the power train on this dozer uses a Torqflow transmission, not a standard Manual Transmission with a clutch pedal. Understanding the hydraulic controls is key. The manual’s steering brake section clarifies how the brake check valve and booster work – topics you’d never find in a Manual Transmission repair guide.

How many pages does this manual have?

1202 pages.

Does it include wiring diagrams?

Yes, the Power Train section includes hydraulic circuit diagrams. For complete electrical, check the structure sections – there are diagrams for the oil cooler fan drive and steering brake systems.

Can I use this for a different serial number range?

This manual covers D455A-1 machines with serial numbers 1013 and up. However, many procedures reference specific machine serial number ranges, especially for the oil cooler fan drive pump (1301 and up), engine mounting (1013-1500 vs 1501 and up), and PTO disassembly. Always check the serial number range listed in each section before following a procedure. Using the wrong range can lead to incorrect components or torque specs, which I’ve seen cause oil leaks and premature bearing failures. The manual is explicit about these ranges – pay attention to them.

What is the publication year?

1988, printed in Japan. The manual includes revision pages marked with revision numbers (e.g., ⑤) that show updates made through that year.

If you have a D455A-1 in your shop, having this OEM manual on your tablet or printed out saves time and prevents mistakes. Komatsu PW95R-2 Workshop Manual – 520 Pages of Factory Specs is another option for smaller dozers, but for this 60-ton machine, go with the source. Access the Factory Manual from AutoRepairManuals today.