Description

Doosan G643E LP Engine, G643 LP Engine, G35-S, G40S-5, G45S-5 2007 Service Manual

If you’re tearing down a Doosan G643E LP Engine or any of the G35-S, G40S-5, G45S-5 models from 2007, you need the factory service manual — not a reprint, not a scanned copy from some forum. I’ve been turning wrenches for 28 years, and I can tell you the difference between guessing and having the OEM spec on paper is the difference between a job that stays together and a comeback that costs you a weekend. This 308-page document came straight from Doosan’s printing press in May 2007. Every torque value, every clearance spec, every fuel system check procedure — it’s all here, photographed and diagrammed the way the engineers intended. You don’t get to skip steps because somebody on YouTube said it’s fine. You follow the factory order or you risk pulling a head bolt through the casting. Your call.

2007 Doosan G643E LP Engine Service Manual — 308 Pages of Factory Data

Chapter 1 covers general information you need before you touch anything: the tightening torque table on page 10, recommended lubricants and capacities on page 12, and engine model/serial number locations. The engine power and torque curves for the G643F and G643FE are on page 16. That’s not guesswork — those are dynamometer results from Doosan’s test cells. Chapter 2 walks you through recommended maintenance: test fuel system for leaks (page 17), inspect vacuum lines, foot pedal operation, and a full maintenance schedule on page 29. If you’re running a shop that sees these lift trucks or industrial engines regularly, you’ll appreciate the compressed pressure check procedure on page 20 — it saves you from chasing phantom misfires.

Torque Specs and Fluid Capacities

Page 33 lists the torque specifications for the engine mechanical system: cylinder head bolts, main bearing caps, connecting rods. These are not generic values — they are specific to the G643E and G643 LP Engine blocks. Use a beam-type torque wrench that’s been calibrated within the last year. The manual calls out lubricant grades and capacities in imperial units — quarts and pints, not liters. Coolant concentration vs. specific gravity table on page 22 tells you exactly what mix prevents cavitation in the cast-iron liners. Follow it.

Engine Mechanical System: Cylinder Head & Bottom End

Chapter 3 is where the real work happens. Engine exploded view on page 41, construction details on page 45, and a statement on cleanliness and care that every apprentice should memorize. RTV sealer and anaerobic gasket eliminator usage is spelled out on page 46 — use the wrong stuff and you’ll be pulling the pan again inside a month. Thread repair instructions are on page 47. Special tools list on page 48 tells you exactly what you need to do the job without damaging the components. Cooling system testing and adjusting starts on page 52 — thermostat removal, water pump inspection, radiator cap pressure test. Engine lubrication section begins on page 57 with oil pump clearance checks and pressure specs. If you’re rebuilding one of these engines, you need the data on page 33 for torque and page 48 for tooling. No shortcuts.

Why Factory OEM Documentation Matters

I’ve seen aftermarket manuals that claim to cover the G643E G643 LP Engine but leave out the TMAP sensor check (page 28, exclusive to the G643E). They also skip the fuel lock-off test procedure (page 27). When you’re dealing with LP fuel systems — especially on a forklift that runs indoors — you don’t guess on leak-down rates. This manual includes the safety warnings from page 3 that Doosan printed in bold red text. Warnings about propane vapor accumulation, battery spark risks, and proper ventilation. The aftermarket reprints strip those out to save paper. That’s not a service manual — that’s a liability. You get the original OEM print with all safety notices intact. Related manuals you should pair with this one: Doosan Lift Trucks Operation & Maintenance Manual for daily operator checks, Doosan Power Train Transmission Manual 2007 if you’re also servicing the drivetrain, and Doosan Power Train Drive Axle Brake Manual for brake system work. For general transmission knowledge, the Manual Transmission article on Wikipedia provides a solid overview of fundamentals, but it won’t give you Doosan-specific clearances — neither will Manual Transmission articles from generic sources. That’s why this manual exists.

Get the Right Torque Data Before You Bolt Anything

One of the first things I check in any service manual is the torque chart. This one has it on page 10 (Chapter 1) and again on page 33 (Chapter 3) with engine-specific values. If you’re used to working on domestic V8s, the step pattern for the G643E head bolts is different — the manual shows the sequence in a clear diagram. Use a 3-step torque-plus-angle method as specified. Skip the angle and you’ll blow the head gasket at 300 hours. The data is verified — the 2007 publication year means it matches the production run exactly. No revisions, no corrections past that year. For these models, that’s what you need.

Does this manual cover the G643 LP Engine as well as the G643E?

Yes. The G643 LP Engine is covered alongside the G643E. The TMAP sensor section on page 28 is marked “G643E only” — everything else applies to both. 308 pages, same binding.

I have a G35-S forklift — will the fuel system procedures match my LP setup?

The G35-S, G40S-5, and G45S-5 all use the same base G643E/G643 LP Engine family. Fuel system maintenance on pages 27-28 — LP filter replacement, pressure regulator inspection, air/fuel valve mixer check — are identical across these models. The manual was written for the engine, not the chassis, so it applies to any application that uses these engines: forklifts, industrial sweepers, aerial lifts. The only difference you’ll encounter is the intake plumbing layout, which is covered in the engine exploded view on page 41. Do not use aftermarket parts unless they match the OEM part numbers listed in the manual’s specification tables. I have seen a G40S-5 come in with a swapped regulator that caused a lean misfire at idle — the factory spec on page 28 would have caught it. The manual includes the original Doosan illustration of the LP converter assembly, including hose routing and vacuum line orientation. That detail matters because a misrouted vacuum line can cause the lock-off to stay closed, starving the engine. The manual also covers the fuel lock-off test procedure — a simple vacuum pump and pressure gauge check that takes 10 minutes and eliminates the most common cause of no-start on LP systems. If you have the G643E, the TMAP sensor diagnostic on page 28 gives you voltage readings at key-on, idle, and full throttle. Compare those to your multimeter readings and you’ll pinpoint a bad sensor in minutes. All of this is in the 308 pages you are buying.

If you are a DIY mechanic who keeps a Doosan G35-S, G40S-5, or G45S-5 in the garage, or a shop that sees these engines weekly, this 2007 service manual is the difference between a profitable repair and a parts cannon. The OEM torque values alone are worth the price — they’ll keep bolts from stretching and gaskets from weeping. Access the Factory Manual from AutoRepairManuals and put it on your shop tablet or print it out for the binder. Your torque wrench will thank you.