Case 450 Crawler Tractor Service & Repair Manual – 1973

This J.I. Case service and repair manual covers the 1973 Case 450 Crawler and its mounted equipment. Burl. Form 9-72332, May 1973 combines crawler-specific chapters with shared engine material for the 188D diesel and 188G, 159G, and 148G spark-ignition engines.

PDF Bookmarks, Diagram Detail, and Page Count

Section access and wiring detail: Embedded bookmarks provide access to the main sections. The manual body is not text-searchable. Small labels in wiring and hydraulic diagrams require zooming.

The download contains one printable, 643-page PDF: 642 manual pages, including the two-page sprocket-mounting supplement, plus one additional cover page.

Engine Overhaul, Power Train Testing, and Attachment Service

The following selected topics outline the repair coverage rather than reproduce the full contents. Further sections address battery load testing and removal of the seat and tank assembly.

• Engine repair: Step-by-step engine removal and installation, diesel cylinder-head and valve service, engine-block overhaul, cylinder-sleeve inspection, and cooling-system maintenance.

• Fuel systems: Roosa Master DB pump installation and timing, injector testing and adjustment, fuel-filter service, system bleeding, and throttle-linkage adjustment.

• Power train and brakes: T145 transmission overhaul, torque-converter diagnosis, final-drive service, clutch-pack inspection, master-cylinder repair, and brake bleeding.

• Equipment hydraulics: Pump testing, loader and dozer control-valve service, Commercial-Shearing backhoe valves, relief-pressure checks, and hydraulic-cylinder overhaul.

• Track and suspension: Sealed-track assembly, pin and bushing wear checks, idler alignment, roller service, track adjustment, and sprocket installation.

• Electrical diagnosis: Wiring diagrams, starting and charging circuit checks, ignition-system testing, starter overhaul, and generator and voltage-regulator service.

• Mounted equipment: Loader and dozer repairs, Models 26, 26C, 32, and 33 backhoes, Models 9 and 19 Gearmatic winches, ripper installation, and rollover-protection inspection.

This manual is suited to mechanics experienced in crawler overhaul and hydraulic testing; injector service requires a test stand and dedicated tooling.

Cylinder Heads, Sleeves, and Timing Gear Service

Compression testing and valve-train inspection are supported by cylinder-sleeve brush deglazing and honing procedures. Sleeve-protrusion charts guide cylinder-head fire-ring selection, while valve-face grinding drawings explain the seating geometry.

The engine chapters distinguish diesel and spark-ignition timing-gear arrangements and include camshaft-nut, crankshaft-hardware, and cylinder-head fastener torques. Bearing-installation notes explain how dirt behind the bearing liners can create hot spots and cause premature failure.

Cooling and intake: Radiator, water-pump, and thermostat work is supported by oil-bath and dry-type air-cleaner instructions. The restriction indicator is tested with a manometer; it is nonadjustable and serviced as an assembly. Maintenance charts and U.S./metric torque tables provide routine service references.

Injection Equipment and Gasoline Fuel Controls

Roosa Master pump coverage addresses removal, installation, timing, and external speed adjustments, rather than internal pump rebuilding. The manual reserves authorized engine-speed adjustments for Case dealers.

Injector procedures cover opening pressure, leakage, leak-off, spray pattern, reconditioning, and adjustment using test stand M20322 and tool kit M20520. Pump-installation cautions explain how missing fuel-line connector washers can cause pump seizure.

Zenith carburetor specifications apply to the 188G and 159G; Marvel-Schebler specifications apply to the 148G. Governor and carburetor linkage inspection and adjustment are also documented.

Transmission and Hydraulic Fault Isolation

The factory flowmeter tests distinguish charging-pump losses, control-valve leakage, and leakage at clutch seals or oil-control rings. This helps locate the source of poor drive performance before major teardown. Stall checks separately address gasoline and diesel engines, with loader and dozer test conditions.

Transmission repair distinguishes aluminum-piston and cast-iron-piston clutch packs. The transmission/converter hydraulic diagram supports diagnosis alongside charging-pump, declutch-lockout, and final-drive procedures.

Attachment hydraulics: Component-specific coverage includes D31254/D41390 equipment pumps, the D39297 4-In-1 bucket relief valve, anti-rollback check valves, and diversion valves. Loader hydraulic diagrams distinguish production configurations; separate sections address backhoe boom lockout and cushioned boom and swing cylinders.

Undercarriage, Attachments, and Electrical Variants

Track procedures distinguish earlier assemblies from crawler S/N 3050801 and after. On the later machines, the welded recoil-spring housing is serviced only as a complete assembly. The sprocket-mounting supplement expands the bolt-tightening procedure.

Backhoe chapters include removal, disassembly, reassembly, pivot shimming, and extendable-dipper or extendable-boom work. Gearmatic winch chapters cover brake and clutch service, hydraulic-line bleeding, gear adjustment, and adapter installation. Rollover-protection coverage includes inspection and replacement requirements after an impact.

Wiring references: Separate diesel wiring diagrams cover the change at crawler S/N 3038436. Spark-ignition and Return-To-Dig wiring diagrams support circuit tracing, including the loader's different return-control arrangements.

Follow the manual's lifting and pressure-relief precautions when working around raised loader arms, hydraulic lines, and heavy drivetrain assemblies.

A Preview of Engine Clearances and Thermostat Data

For the 188D, the detailed engine tables list main-bearing oil clearance of 0.0012–0.0042 inch. The crawler's diesel specifications give oil pressure of 50–70 psi with the engine warm and operating at rated speed.

The cooling-system reference specifies that the thermostat starts opening at approximately 177°F and is fully open at 202°F.