1998 Clark CMP 15/18 & CMP 20/25/30 Service Manual FSM (P/N SM 638)

This official 281-page Clark PDF publication (P/N: SM 638, Revision 1) covers the 1998 CMP 15, 18, 20, 25, and 30 industrial forklifts. It focuses specifically on models running the Mitsubishi 4G63 and 4G64 gasoline and LPG power plants. Whether you are rebuilding the engine block, diagnosing fuel delivery, or servicing the chassis, this reference provides the exact factory baseline required for the repair job.

• Contains over 80 pages dedicated specifically to exploded-view assembly diagrams and maintenance checklists
• Details complete engine tuning specifications, including exact torque settings for the 4G63/4G64 configurations
• Outlines factory procedures for the engine overhaul, cooling, fuel, and transmission systems
• Covers step-by-step rebuilding for TA-12 transaxles, hydrostatic steering units, load-sensing priority valves, hydraulic gear pumps, and lift cylinders
• Features essential circuit wiring diagrams, hydraulic schematics, troubleshooting charts, PM inspection forms, multi-piece rim matching charts, and pinion gear tooth contact patterns

Service and Maintenance Overview

You need exact tolerances when tearing down a CMP-series lift. Having these factory specifications on the bench significantly cuts down on diagnostic time, allowing technicians to confidently handle major in-house servicing instead of outsourcing heavy chassis repairs to a dealership. This manual breaks down the maintenance schedules by operating hours, pinpointing lubrication points and inspection intervals for both LPG and gas setups. It covers safe lifting, jacking, and towing protocols to keep the shop floor secure before the real work even begins.

Expect clear documentation on engine removal and installation, cylinder head service, and timing belt routing. For heavy overhaul work, the manual lists exact piston clearances, ring end gaps, and silent shaft bearing tolerances required to bring the Mitsubishi engines back to factory spec. The factory documentation also walks you through step-by-step procedures that save expensive workshop labor, such as adjusting the upright mast shims, setting the drive axle ring and pinion backlash, and overhauling the internal expansion duo-servo drum brakes.

Engine and Technical Specifications

This comprehensive documentation delivers precise metrics for complete system tuning. You get reliable baseline figures, including a spark plug gap of 0.7–0.8 mm (0.028–0.031 in) and a compression pressure reference of 1880 kPa (163.5 psi) at 300 rpm. The cooling system capacity sits at 8.5 liters, with the thermostat engineered to open right at 82°C.

When working on these specific Clark models, mechanics must be aware of certain repair traps. During a powershift transaxle stall test to diagnose clutch slippage, exceeding the 30-second testing limit will overheat the torque converter past 250°F (120°C), resulting in catastrophic transmission seal degradation. Furthermore, when servicing the upright hydraulic circuit, installing the flow limiting valve backwards completely disables its fail-safe function, creating a severe carriage drop hazard in the event of a hose rupture.

When reassembling the unit, structural integrity relies on proper torque. Upright trunnion bolts, for example, require exactly 75–80 Nm (55–59 ft-lbs). Keep in mind that heavy machinery maintenance carries inherent physical risks. Always cross-reference these operational baselines with the full OEM procedures provided in the manual before beginning any hands-on mechanical work to ensure total shop safety and proper equipment operation.