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Doosan GC25P-3 - User Manual

Doosan GC25P-3
182 pages
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G430 LP Engine
Standard Version
Low Emission Version
G20P-3, G25P-3, G30P-3
GC20P-3, GC25P-3, GC30P-3
SB4005E01
Oct. 2001
Service Manual

Table of Contents

Questions and Answers

  • J
    Julia MaxwellAug 12, 2025
    Why is there no spark in my Doosan GC25P-3?
    • W
      William HensleyAug 13, 2025
      If your Doosan Engine has no spark, it could be due to several reasons. Start by inspecting and replacing the distributor cap or spark plug leads if they are arcing. Also, replace the spark plugs if they are fouled, burned, or have cracked porcelain. Check the battery and electrical connections, and replace the spark plug wires if they are broken or have faulty insulation. If these steps don't solve the problem, replace the ignition switch or inspect and replace any other faulty ignition components. Clean or replace the distributor cap if it is cracked or dirty. Finally, disconnect the tachometer and test again to rule out a shorted tachometer.
  • M
    Marissa MccormickAug 16, 2025
    Why is my Doosan GC25P-3 Engine spark knocking?
    • R
      russellnorrisAug 16, 2025
      If your Doosan Engine is experiencing spark knock, it could be due to several reasons. First, try retarding the ignition timing. If that doesn't solve the problem, switch to a higher quality fuel. Also, inspect the cooling system to ensure the engine isn't running hot. Finally, clean the engine to remove any carbon deposits.
  • K
    Kathy ReevesAug 20, 2025
    What to do if the Doosan GC25P-3 will not crank over?
    • C
      Christopher PachecoAug 20, 2025
      If your Doosan Engine won't crank over, there are several potential causes. Start by charging the battery and checking the wiring for damage or loose connections. If that doesn't work, check if the circuit breaker has tripped and reset it if necessary. Other possible issues include a bad ignition switch, a bad starter solenoid, or a defective starter motor, all of which would need to be replaced.
  • R
    Richard ParkerAug 25, 2025
    How to fix poor engine idle on a Doosan GC25P-3?
    • J
      James CarrAug 25, 2025
      To fix a poor engine idle on your Doosan Engine, begin by checking the air breather for clogs and clean or replace it as needed. Then, adjust the idle-fuel mixture. Inspect and replace any faulty spark-plug wires that may be arcing. Other solutions include using higher grade fuel, adjusting the ignition timing, or replacing the spark plugs. You may also need to replace the ignition coil, clean or replace the distributor cap, or clean the carburetor. Repair any leaks at the intake manifold or carburetor base. If these steps don't resolve the issue, perform a compression check. Finally, tighten or replace the distributor if it is loose or worn, and inspect and replace any damaged components such as the head gasket, exhaust manifold, cracked head, or valve seat.
  • M
    michaelbrownAug 27, 2025
    Why is my Doosan GC25P-3's alternator noisy?
    • L
      Linda HarveyAug 27, 2025
      A noisy alternator in your Doosan Engine can stem from several causes. Begin by tightening the mounting bolts. If the noise persists, replace the drive belt if it's worn, frayed, or loose. Additionally, tighten the drive pulley. If the issue continues, consider replacing or cleaning the bearings if they are worn or dirty. Lastly, replace the defective diode trio or stator if they are faulty.
  • M
    myersnicoleSep 1, 2025
    What causes malfunctioning instruments or gauges in a Doosan Engine?
    • H
      Harold BlackSep 1, 2025
      Malfunctioning instruments or gauges in your Doosan Engine can be caused by faulty wiring, loose, or corroded terminals, so check and repair the wiring. Other potential causes include a bad key switch, a faulty gauge, or a faulty sender, all of which would need to be replaced.
  • F
    frankbrianSep 4, 2025
    What causes noise around the valve cover area on a Doosan GC25P-3 Engine?
    • T
      Theresa FranklinSep 4, 2025
      Noise around the valve cover area of your Doosan Engine can be due to several factors. It could be that the rocker arm is striking the valve cover, in which case you should adjust the rocker arm. Alternatively, the rocker arm might be out of adjustment, requiring you to re-adjust it. Other potential causes include a worn rocker arm, a bent push rod, or a collapsed lifter, all of which would need to be replaced.
  • J
    Jennifer RichardsonSep 8, 2025
    Why is there water found on top of the pistons in my Doosan GC25P-3 Engine?
    • L
      littlewilliamSep 8, 2025
      If you find water on top of the pistons in your Doosan Engine, it could be due to a cracked exhaust manifold (if water cooled), which would need to be replaced. Another cause could be improper installation of the manifold-to-elbow gasket (if water cooled); reinstall it properly. Also, check for and tighten any loose cylinder head bolts. Other potential causes include a blown cylinder head gasket, a cracked valve seat or porous/cracked casting, all of which would need to be inspected and replaced.

Summary

General Information

Shop Safety Precautions

Safety in the workplace, covering precautions for working on engines and fuel systems.

Fuel Information and LPG Properties

Information about LPG, its properties, grades, and comparison to gasoline.

Engine Performance Factors: Air Temperature

Explains how intake air temperature affects engine horsepower output.

Engine Performance Factors: Altitude

Discusses the impact of altitude on engine horsepower and fuel mixture.

General Engine Description and Operation

Provides an overview of the engine and its main components.

Cleanliness, Gasket Replacement, and Sealant Use

Covers proper cleaning, gasket procedures, and types of sealants.

Tools and Equipment for Engine Service

Lists essential tools and equipment required for engine maintenance.

Specifications

Technical Engine Data

Provides general engine specifications including type, displacement, bore, stroke, and compression ratio.

Fuel System Specifications

Details specifications for standard and low emission LP fuel systems, including pressures and components.

Engine Mechanical Data and Tightening Specifications

Includes fastener tightening specifications and lists of sealers, adhesives, and lubricants.

Maintenance Procedures

Fuel System Testing and Inspection

Procedures for testing fuel system for leaks and inspecting fuel lines and fittings.

Engine Oil, Coolant, and Belt Maintenance

Covers engine oil level checks, coolant checks, and accessory drive belt inspection.

Ignition, Vacuum, and Compression Checks

Procedures for inspecting ignition system, vacuum lines, and performing compression checks.

Maintenance Schedule

Provides a schedule for routine maintenance tasks based on interval hours.

Troubleshooting Engine Performance

Engine Performance and Starting Issues

Diagnoses common engine performance complaints like poor idle or starting problems.

Engine Noise and Oil Pressure Problems

Guides on diagnosing engine noise sources and oil pressure issues.

Cooling System and Fuel System Troubleshooting

Addresses overheating and issues related to the LP fuel system, including stalls and performance.

Starting System Service

Starting System General Description

Explains the function and components of the engine starting system.

Starting System Diagnosis and Testing

Provides a procedure for diagnosing starting system issues and testing components.

Start Relay and Starting Motor Procedures

Details tests for the start relay and procedures for starting motor removal/installation.

Charging System Service

Charging System General Description

Overview of the alternator's function in charging the battery.

Alternator Specifications and Types

Lists available alternators, their manufacturers, series, and specifications.

Alternator Removal and Installation

Step-by-step instructions for removing and installing the alternator.

Ignition System Service

Ignition System Overview and Types

Compares conventional and High Energy Ignition (HEI) systems.

Ignition System Components and Operation

Describes modules, pulse generators, coils, and magnetic flux paths.

EST Distributor and Component Testing

Details the EST distributor, its testing, and related component checks.

Ignition Timing Adjustment

Procedure for checking and adjusting the spark timing for the EST system.

LP Fuel System

LP Fuel System Overview and Components

Describes the basic components of the LP fuel system and their interconnections.

Fuel Tank, Relief Valve, and Carburetor

Details the fuel tank, LP relief valve, and carburetor functions.

Carburetor Adjustment Procedures

Guides on adjusting low idle speed, idle mixture, and power mixture.

Fuel System Leak Checks and Converter Inspection

Procedures for checking fuel system leaks and inspecting the converter.

LP Converter and Fuelock Service

Covers checking, cleaning, disassembly, and assembly of LP converter and fuelock.

LP Fuel System (Low Emission Version)

Low Emission System Overview and Components

Explains the closed-loop system with catalytic muffler and ECU for emission control.

Fuel Lock, Pressure Regulator, and Mixer Operation

Details the function of electric fuel lock, pressure regulator, and variable venturi mixer.

Catalytic Muffler and ECU Functionality

Describes the catalytic muffler's role in emission reduction and the ECU's control logic.

Fuel System Component Tests and Adjustments

Procedures for checking and cleaning the LP carburetor and inspecting fuel lock/control valves.

LP Converter Service Procedures

Covers disassembly, assembly, and inspection of the LP converter.

Governor System Service

Governor System Overview and Components

Describes governor types, function, and key components.

Governor Operation Modes

Explains governor operation during engine stopped, low, and high load conditions.

Governor Adjustment Procedures

Provides steps for adjusting engine speed and addressing surging issues.

Lubrication System Service

Lubrication System Overview

Details the engine lubrication system, oil flow, and components.

Lubrication System Problems and Diagnosis

Covers common lubrication issues like oil consumption, low/high pressure, and component wear.

Oil Pressure Check Procedure

Instructions for checking engine oil pressure and acceptable values.

Cooling System Service

Cooling System General Description

Explains the pressurized cooling system, components, and operation.

Cooling System Testing and Inspection

Covers visual inspection, pressure cap testing, leak checks, and thermostat tests.

Thermostat and Heat Problem Diagnosis

Details thermostat function, testing, and troubleshooting heat problems.

Cooling System Recommendations and Coolant

Provides coolant mixture recommendations and antifreeze guidelines.

Belt Adjustment and V-Belt Diagnosis

Covers drive belt adjustment, tension, and diagnosis of belt failures.

Cooling System Service Procedures

Instructions for draining, filling, and flushing the cooling system.

Radiator Service and Thermostat Replacement

Details radiator cleaning, scale removal, and thermostat replacement.

Water Pump Replacement

Step-by-step instructions for removing and installing the water pump.

Base Engine Service Procedure

Engine Component Disassembly Steps

Illustrates disassembly of major engine components like flywheel, distributor, and manifolds.

Crankshaft, Rods, and Bearings Service

Covers removal, cleaning, inspection, and installation of crankshaft, rods, and bearings.

Piston and Cylinder Bore Service

Details procedures for piston and cylinder bore measurement, cleaning, and assembly.

Camshaft and Oil Pump Service

Procedures for camshaft and oil pump inspection, installation, and assembly.

Cylinder Head and Valve Train Service

Covers cylinder head disassembly, cleaning, inspection, and valve train service.

Final Engine Assembly Procedures

Guides on installing crankshaft seals, bearings, pistons, camshafts, and covers.

Special Tools and Equipment

Illustrated Special Tools

Illustrations and names of specialized tools for engine service.

Fuel System Troubleshooting Kits

Details the contents of the ITK-1 Pressure Gauge Kit and FSA-1000 Fuel System Analyzer.

Doosan GC25P-3 Specifications

General IconGeneral
BrandDoosan
ModelGC25P-3
CategoryEngine
LanguageEnglish

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