John Deere 444D-644D Loader Workshop Technical Manual (1985-1987) – 400 Pages | OEM Specs

John Deere 444D, 544D, and 644D Loader Technical Manual - 1987 Edition

John Deere Technical Manual TM-1341 provides essential diagnostic, operational, and testing procedures for the D-Series loader range. To ensure maximum operational uptime, the air filter restriction indicator must be inspected via the left engine side shield to verify it does not show red, preventing premature engine wear caused by carbon build-up and elevated combustion temperatures.

Chassis Infrastructure: Technical Applicability & Serial Ranges

Standard Configuration Models (Serial No. —512188)

• John Deere 444D Four-Wheel Drive Loader (1985–1987)
• John Deere 544D Four-Wheel Drive Loader (1985–1987)
• John Deere 644D Four-Wheel Drive Loader (1985–1987)

Updated Configuration Models (Serial No. 512189—)

• John Deere 444D Four-Wheel Drive Loader (1987 Revision)
• John Deere 544D Four-Wheel Drive Loader (1987 Revision)
• John Deere 644D Four-Wheel Drive Loader (1987 Revision)

Specialized Commercial Variants

• John Deere 444D Log Loader (Chassis-Specific Tiring)
• John Deere 544D Feller-Buncher (Specialized Lift Arm Relief)
• John Deere 544D Log Loader (Heavy-Duty Logging Spec)
• John Deere 644D Log Loader (High-Capacity Logging Spec)

Operational Parameters: Efficiency and Safety Benchmarks

• Precision diagnostics are achieved through the three-step "Repair, Operation, or Tests" methodology utilizing specialized yellow and

Calibration Data: Engine & System Performance

• Slow Idle (644D): 900 ± 25 rpm (Increased from previous specifications).
• Fast Idle (444D): 2600 ± 25 rpm.
• Fast Idle (544D/644D): 2400 ± 25 rpm.
• Main Hydraulic System Relief (444D): 2250–2450 psi (155–159 bar).
• Turbocharger Boost Pressure (644D): 16–22 psi (1.24–1.52 bar) at 2200 rpm.
• Unloading Valve Closing Pressure: 1880 ± 75 psi (130 ± 5.18 bar).

System Architecture: Visual Navigation Aids

• Hydraulic System Schematics: Covers Steering, Brake, and Loader functions.
• Power Train Block Diagrams: Illustrates Neutral, Low, High, and Reverse torque paths.
• Electrical Wiring Standards: Detailed color-coded and numbered circuit mapping for Serial No. 512189 and above.

Table of Contents

• Section I: General Information (Safety, Specifications, Torque, Lubricants)
• Section 9005: Operational Checkout Procedure (Seven-Step Diagnostic Logic)
• Section 9010: Engine Operation and Tests (Theory, Adjustments, Power Tests)
• Section 9015: Electrical System Operation and Test (Charging, Starting, Gauges)
• Section 9020: Power Train (Transmission, Brakes, Differentials)
• Section 9025: Hydraulic System (Priority Valves, Reliefs, Pump Performance)
• Section 9031: Heating and Air Conditioning (Refrigerant R-12 Procedures)

Operational Limits & Component Specifications

• Hardware Torque: Grade 8 Customary hardware (1/2") requires 120 lb-ft (163 N-m).
• Wheel Retainer Cap Screws: 300 ± 30 lb-ft (410 ± 40 N-m).
• Fluid Capacities (644D): Fuel Tank (67 gal / 254 L); Hydraulic Reservoir (100 qt / 95 L).
• Lubricant Grade: John Deere HY-GARD® Transmission and Hydraulic Oil (J20A/J20B).
• Accumulator Pressure: Maximum working pressure of 3200 psi (22060 kPa) using dry nitrogen only.

FAQ

Does this manual cover the specific serial number breaks for the D-series loaders? Yes, the manual provides comprehensive coverage for the 444D, 544D, and 644D models, with specific technical updates for units starting at serial number 512189. It includes critical revisions such as the inclusion of a thrust washer in the transmission case for the first turbine drive gear and updated assembly instructions for the reverse and low-range clutch packs for these later units.

What is the specific slow idle specification for the 644D model according to the latest revisions? The slow idle for the 644D Loader has been specifically increased to 900 ± 25 rpm to ensure optimal engine stability and performance. This represents a critical update from earlier documentation and is essential for technicians performing governor adjustments or engine troubleshooting.

Can I find detailed diagnostic procedures for the hydraulic and steering systems? The manual contains Section 9025, which is dedicated to Hydraulic System Operation and Tests. It details specific procedures for testing the priority valve, checking main system relief pressures (ranging from 2250 to 2450 psi on the 444D), and performing pump efficiency tests to identify internal leakage or component wear.

What specialized maintenance insight is provided for the air conditioning system? A vital instruction for maintaining the air conditioning system is the strict prohibition of using hydraulic hoses as replacements; the manual mandates using only certified hoses meeting SAE J51b requirements to prevent refrigerant gas migration. Additionally, it specifies using 525 viscosity refrigerant oil on all O-rings and connections to ensure leak-proof joints during assembly.

How does this digital technical manual improve efficiency for urgent field repairs? This digital edition allows for instant navigation through the specialized yellow and gray tabbed diagnostic sections, such as Section 9005 for Operational Checkout Procedures. Technicians can immediately print high-resolution wiring schematics or torque sequence charts—such as the 300 lb-ft requirement for wheel retainer cap screws—ensuring factory-standard accuracy directly at the machine site.