Description

Hitachi Sumitomo 330LC, 350H, 350LCH, 370MTH, ZX330 Technical Manual

You have a Hitachi Sumitomo 330LC, 350H, 350LCH, 370MTH, ZX330 Technical Manual in your hands — 334 pages of factory-authorized data that tells you exactly how to test, diagnose, and adjust these excavators. Aftermarket PDFs get the relief pressure wrong. I have seen a 350LCH come into my shop with a swapped main relief valve because some online guide said 3200 psi. Factory spec? Different. This manual ends that guessing.

Section 4 alone — Operational Performance Test — runs from engine compression checks to swing motor leakage. You want to know if your 370MTH travel motor is draining too much? Page 73 gives the procedure and the acceptable drainage rate. No interpretation. No third-party commentary. Just the OEM number.

Engine Overhaul Coverage

Engine tests in this manual cover compression pressure, valve clearance adjustment, nozzle check, injection timing, and lubricant consumption. The valve clearance adjustment procedure is written for a technician who has done it before — it gives the cold clearance spec and the order to tighten. If you skip the sequence, you will bend a pushrod. I have seen it. The manual also includes the injection pump P-Q curve data so you can verify fuel delivery against the factory curve instead of guessing.

For the ZX330 and 330LC, the engine learning procedure is in the Adjustment subsection. After you replace the fuel injection pump or the governor actuator, you have to run the engine speed adjustment and learning routine. The manual walks you through the Dr. ZX monitor steps. Miss that step and the engine will hunt at idle. Period.

7 Systems Covered in Troubleshooting

Troubleshooting Section 5 is split into three parts — A, B, and C. Part A covers fault codes 01 through 19. Fault code 07 (abnormal engine control dial angle) is a common one on the 350H. The manual gives the sensor voltage range and the wiring check procedure. Part B is the symptom-based section: engine system, all actuator system, front attachment, swing, travel, and other systems. Each symptom has a correlation table linking the symptom to the most likely failed part. Part C handles monitor malfunctions — coolant temp gauge, fuel gauge, indicator lights, LCD, hour meter. If the LCD on your 350LCH goes blank, the manual tells you which connector pins to back-probe.

Does This Manual Cover the Fuel System?

Yes. The injection pump section includes the nozzle check procedure and injection timing specs. The manual also covers the governor lever and fuel cut lever position adjustment. If you are working on a 370MTH and the engine won’t reach high idle, the governor linkage adjustment is on the Adjustment page. The manual also includes the Dr. ZX monitoring item list so you can read live fuel delivery data through the diagnostic port.

What Torque Values Are Listed?

Torque values appear throughout the component test and adjustment sections. The main pump delivery pressure test requires a specific torque on the test port fitting to avoid leaks. The swing motor drain port plug has a torque spec. The manual does not list every bolt on the machine — that is what the Workshop Manual is for — but every pressure test port and adjustment locknut has a torque value. If you need the full engine and chassis bolt torque table, get the companion HITACHI ZAXIS 330/350/370 Workshop Manual.

Source Validity: OEM vs Aftermarket

This is a Hitachi Sumitomo factory Technical Manual, part of the three-volume set (Technical Manual Operational Principle, Technical Manual Troubleshooting, Workshop Manual). The file name — HITACHI_ZX330-330LC-330LCX-330H-350H_Technical_Manual_en-31113020623.pdf — matches the OEM part numbering system. Aftermarket manuals often omit the Dr. ZX special function section and the adjustment data list. This one includes both. The Dr. ZX service mode allows you to override solenoid valves for testing. Aftermarket reprints leave that out because they copy from a copy. This is a direct scan of the original OEM print.

If you want the full disassembly and assembly procedures, the Hitachi ZAXIS 330 350 370 Series Workshop Manual is the companion volume. For smaller Sumitomo machines, the Sumitomo SH200/SH220-3 Product Concept Manual covers the hydraulic system theory.

FAQ

Will this manual help me diagnose a swing brake issue on a 350LCH?

Yes. Section 5 Troubleshooting B includes a swing system troubleshooting subsection. It lists the relationship between swing brake symptoms and the likely failed part — swing motor, solenoid valve, or pilot pressure. The manual also includes the swing motor drainage test procedure in Section 4.

Does it include wiring diagrams?

No. This is the Troubleshooting volume. Wiring diagrams are in the Workshop Manual. This manual includes electrical component layouts — relay locations, monitor and switch positions — but not full schematic diagrams.

What is the page count?

334 pages.

Can I use this manual for a ZX330LC that has a different engine serial number?

Yes. The manual covers the ZX330, 330LC, 330LCX, 350H, 350LC, 350LCH, 350LCN, and 370MTH. The engine test procedures — compression pressure, valve clearance, injection timing — apply across the series. The Dr. ZX fault code list is the same for all models. If your machine has a different engine family, verify the injection pump P-Q curve against the manual’s curve to confirm compatibility.

You need the factory data to get these machines running right. Access the Factory Manual now and put the OEM specs on your bench.