Part of the Case Repair Manuals.
Wrenching on a Case 621C, 721C, or 921C loader? This 760-page Case service manual PDF (OEM #7-13502) walks you through every system on these wheel loaders, from engine and fuel to steering, power train, brakes, hydraulics, and mounted equipment. Inside: a full troubleshooting section for transmission, brake, and hydraulic pressure checks, exploded views for teardown work, error code references for the Information and Diagnostic Center, and factory torque tables right up front. You get step-by-step procedures for the loader control valve, brake accumulators, ride control, even cab glass installation. Torque 1/2-inch Grade 5 hardware to 80 to 96 pound feet, and set new AC belt tension at 45 kg (100 pounds). No more chasing pressure problems with borrowed specs. Bookmarked and text-searchable; jump straight to any section or type in the spec you need.
What's Inside This Case 921C, 621C, 721C Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 1-20 | Section Index - General (Standard Torque Specifications, Fluids and Lubricants, Loctite Product Chart) |
| Engines | 23-30 | Engine Removal, Radiator Removal, Stall Test |
| Fuel System | 37-38 | Fuel System Repair, Cummins Engine Service Center |
| Electrical | 39-64 | Section Index - Electrical (Removal and Installation of Starter and Alternator, Electrical Specifications and Troubleshooting, Batteries, Starter and Starter Solenoid, Information and Diagnostic Center, Alternator) |
| Steering | 65-118 | Section Index - Steering (Removal and Installation of Steering Components, Steering Specifications, Pressure Checks, And Troubleshooting, Steering Control Valve, Steering Priority Valve, Steering Cylinders, Center Pivot) |
| Power Train | 119-294 | Section Index - Power Train (Removal and Installation of Power Train Components, Transmission Specifications, Pressure Checks, And Troubleshooting, Transmission, 621C Front and Rear Axle - 721C Rear Axle, 721C Front Axle, Drive Shaft, Center Bearing, And Universal Joints, Wheels and Tires, Transmission Control Valve) |
| Brakes | 447-488 | Section Index - Brakes (Removal and Installation of Brake Components, Hydraulic Brake Troubleshooting, Brake Accumulators, Brake Actuator Valve, Brake Accumulator Valve, Parking Brake) |
| Hydraulics | 489-642 | Section Index - Hydraulics (Removal and Installation of Hydraulic Components, Hydraulic Specifications, Troubleshooting, And Pressure Checks, Cleaning the Hydraulic System, Hydraulic Pump, Loader Control Valve, Cylinders, Remote Control Valves, Combination Valve, Accumulator for Ride Control, Solenoid Valve and Accumulator Valve for Ride Control) |
| Mounted Equipment | 649-760 | Section Index - Mounted Equipment (Pedals and Levers, Air Conditioning Troubleshooting and System Checks, Air Conditioner System Service, Removal and Installation of Air Conditioning Components, Air Conditioning Compressor and Clutch, Loader, ROPS Cab and ROPS Canopy, Cab Glass Installation, Hydraulic Schematic Foldout and Electrical Schematic Foldout) |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Grade 5 Bolts, Nuts, and Studs (1/4 inch) | 108 to 132 Pound Inches | p. 8 |
| Grade 5 Bolts, Nuts, and Studs (5/16 inch) | 204 to 252 Pound Inches | p. 8 |
| Air conditioning drive belt tension (New Belt) | 45 kg (100 pounds) | p. 25 |
| Air conditioning drive belt tension (Used Belt) | 41 kg (90 pounds) | p. 25 |
| Engine Oil Pressure Sender Resistance at 1 Bar | 178 ohms | p. 51 |
| Engine Oil Pressure Sender Resistance at 3 Bar | 90 ohms | p. 51 |
| Coolant and Hydraulic Temperature Sender Resistance at 20°C (68°F) | 3521 ohms | p. 51 |
| Coolant and Hydraulic Temperature Sender Resistance at 105°C (221°F) | 154 ohms | p. 51 |
| Hydraulic Filter Restriction Switch closing setpoint | 310 kPa (45 psi) | p. 51 |
| Fuel Solenoid Resistance (pull in) | 0.82 ohms | p. 51 |
| Fuel Solenoid Resistance (hold in) | 11.3 ohms | p. 51 |
| Air Filter Restriction Switch closing setpoint | 6.4 kPa (0.928 psi) | p. 51 |
Case 921C, 621C, 721C Common Problems This Manual Covers
Case 921C coolant temperature alarm and code 12110, radiator full but gauge climbs to hot
Test the coolant temperature sender before condemning the cooling system. Disconnect it and measure resistance: 3521 ohms at 20°C (68°F), 133.9 ohms at 110°C (230°F), per the chart on page 51. Verify the 5 volt reference at the connector. If the sender checks good, clean the radiator core and pressure test the cap.
Manual Section: Electrical Troubleshooting p. 51Low oil pressure warning and code 21070 at idle, engine sounds normal, oil level full
Verify actual pressure with a mechanical gauge before tearing into the engine; code 21070 trips below 70 kPa (10 psi). If the gauge reads healthy, test the sender resistance against the values on page 51: 178 ohms at 1 bar, 90 ohms at 3 bar, 38 ohms at 5.2 bar. Replace the sender if readings drift out of range.
Manual Section: Electrical Troubleshooting p. 51Transmission overheating under load, code 42125 on display, oil smells burnt after long pushes
Check transmission oil level and condition first; code 42125 is listed on page 197 and sets once oil passes 125°C (257°F). Replace the filter if the restriction warning has been coming on, then run the converter out pressure check and lubrication pressure check from the transmission troubleshooting procedures. Clean packed debris out of the cooler before condemning the converter.
Manual Section: Transmission Troubleshooting p. 197Hydraulic filter restriction light stays on after filter change, loader slow to raise when warm
Check the restriction switch before blaming the new filter; it closes at 310 kPa (45 psi), spec on page 67. Jump the switch connector with the key on: light goes out, the switch is bad. Light stays on, trace the harness for a short. If restriction is real, drain and inspect the oil for contamination.
Manual Section: Electrical Troubleshooting p. 67Air conditioner blows warm air, compressor clutch cycles on and off every few seconds
Inspect the compressor drive belt first; tension it to 45 kg (100 pounds) for a new belt or 41 kg (90 pounds) for a used one, specs on page 25. Clean packed dirt from the condenser fins, then pressure test the system. Rapid clutch cycling usually means low charge from a leaking hose or fitting.
Manual Section: Air Conditioning Troubleshooting p. 25Engine cranks slowly or will not crank in cold weather, batteries recently load tested good
Clean and tighten both battery ground connections and the starter feed before swapping parts; voltage drop across corroded terminals kills cold cranking. If it spins but will not fire, measure fuel solenoid resistance against page 51: 0.82 ohms pull in, 11.3 ohms hold in. An open hold winding lets the solenoid drop out and cut fuel.
Manual Section: Electrical Troubleshooting p. 51Frequently Asked Questions
How do I reset the information center on a Case 921C?
To reset a programmed location back to 000 (factory setting), hold the program/reset switch to reset for 5 seconds. When it is reset, the operator can view the hour meter at any time during normal operating conditions by pressing the reset switch. p. 37
How do I clear fault codes on a Case 921C?
To remove all diagnostic codes from field number locations 071 through 090, press the program/reset switch to program, then press the up/down count switch to up count until the display reads 055. Place the program/reset switch in the OFF position, press the up/down count switch to up count until the display reads 21, and press the program/reset switch to reset. p. 35
What are the replacement specifications for the engine oil pressure sender?
The engine oil pressure sender resistance specifications are 178 ohms at 1 Bar, 90 ohms at 3 Bar, and 38 ohms at 5.2 Bar. p. 51
What is the torque specification for the transmission control valve cap screws?
The cap screws for the transmission control valve should be tightened to 20 Nm (15 pound-feet). p. 123
What is the procedure for checking the nitrogen charge in the brake accumulator?
The nitrogen charge pressure must be 55 to 57 bar (800 to 825 psi). To check, connect the nitrogen charging kit to the accumulator valve stem and read the pressure gauge E. p. 142
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