Description

Komatsu WA320-3, WA320-3 CUSTOM 2007 Workshop Manual

I’ve seen more than a few loaders come through my bay with stripped threads or blown seals because some tech grabbed a generic manual and guessed on the torque. That stops here. This is a Komatsu WA320-3, WA320-3 CUSTOM 2007 Workshop Manual — factory-printed, 597 pages, and packed with the exact numbers Komatsu engineers wrote down. If you’re turning wrenches on a WA320-3 or the WA320-3 CUSTOM, this is the only document you should trust for torque, transmission work, or valve adjustments. Anything else is a gamble.

You’ll find the usual suspects in here: the torque converter hydraulic circuit diagram, transmission control valve breakdowns, and step-by-step testing procedures. But what sets this apart is the completeness. Every spec, every tolerance, every bleeding sequence comes straight from the 2007 factory release. No third-party re-interpretation. No missing pages. Just the data you need to get the job done the first time.

Before you crack a line or pull a valve body, read the disassembly precautions in section 30. Page 30-1 lists the exact order for removing the transmission control valve — skip that and you’ll be fishing snap rings out of the oil pan. The testing section on page 20-1 gives you standard value tables for engine, chassis, and electrical parts, plus the tools required for each check. Don’t own a flow meter? The manual tells you which tests you can skip and which you can’t.

Testing and Adjusting: Valve Clearance and Transmission Pressure

Section 20 starts with a Standard Value Table for Engine — things like valve clearance, injection timing, compression pressure. These are the numbers you set your feeler gauge to. The manual walks you through adjusting valve clearance with the engine cold, step by step. Then it hits the transmission: testing torque converter and transmission oil pressure, bleeding air from the steering circuit, even a procedure for moving the machine when the transmission valve fails. That last one saved my customer a tow bill last month.

Transmission Hydraulics: Factory Circuit Diagrams

Section 10 dives deep into structure and function. You get hydraulic system diagrams for the torque converter and transmission, plus the full piping layout. The transmission control valve is drawn out with every port labeled. If you’re diagnosing a shift hesitation or a no-forward condition, trace the oil flow through the valve spools using these diagrams. The manual includes the kick-down switch circuit and the transmission cut-off function too — both common failure points on these loaders.

What Torque Values Are Listed?

Torque specs are scattered through the manual where they matter. The axle mounting hardware, final drive bolts, brake valve fasteners — each one is called out with a specification in ft-lbs. The manual also gives you the tightening sequence for the torque converter housing bolts. I’ve seen a cracked housing because a tech ran them down in the wrong order. Don’t be that guy. Use the factory specs.

Why OEM Documentation Beats Aftermarket

I’ve got a stack of aftermarket manuals on my shelf that looked okay until I needed the accumulator charge pressure for the WA320-3 CUSTOM. The aftermarket book said “refer to dealer” — worthless. This OEM manual has the full accumulator charge cut-in and cut-out testing procedure, including the pressure values. Same for the brake valve, the priority valve, the 2-way restrictor valve. If you’re serious about not guessing, you buy the factory document. Related manuals worth looking at: Komatsu WA320-3 Workshop Manual – 852 Pages of Factory Specs (a different edition with more pages), Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual, and Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual.

Audience Fit: Who Needs This Manual?

If you’re a home garage guy who bought a used WA320-3 CUSTOM to clear brush on your property, you need this. The troubleshooting section covers engine starting issues, black smoke, oil contamination — real-world stuff. If you’re a shop owner who rents out loaders, you need it for the maintenance standard tables so your techs set the parking brake disc wear limits correctly. Even a fleet mechanic will use the 40-section for wear limits on the final drive and differential. The manual assumes you have basic mechanic skills but doesn’t assume you know Komatsu-specific sequences. For example, the procedure for moving the machine when the transmission valve fails — that’s not in any generic manual. And the electrical troubleshooting charts? They go pin by pin through connector locations and wire colors. For more background on manual transmission systems in general, check Manual Transmission and Manual Transmission for a wider understanding.

Does this manual cover both the WA320-3 and the WA320-3 CUSTOM?

Yes. The manual explicitly covers both models, with serial numbers 50001 and up. The CUSTOM variant uses the SA6D102E-1 engine, and engine details are referenced to the 102 Series Engine Shop Manual included in the package.

Are torque specs listed for the transmission valve body bolts?

Yes. Page 30-1 in the disassembly section gives the tightening sequence and torque for the transmission control valve bolts. Do not reuse the lock nuts.

Can I use this manual for a Komatsu WA380?

No. This manual is written specifically for the WA320-3 series. The hydraulic diagrams, transmission control, and torque values differ on larger models. Get the manual that matches your machine serial number.

What if I need help reading the hydraulic circuit diagrams?

The manual includes a structure and function section that explains each symbol and port. The electric circuit diagrams also have a connector pin arrangement table and connection table starting around section 10. Take fifteen minutes to study the diagram key before you start troubleshooting.

Every time I’ve picked up this manual, I’ve found the exact spec I needed without flipping through a reprint. It’s a solid 597-page reference that stays open on the bench. Whether you’re setting valve clearance after a rebuild or chasing a transmission cut-off fault, the Komatsu factory data is right there. Access the Factory Manual and keep it on your tablet or print it — just have it close when you’re working.