valve clearance interval check will depend on on your Paj model. Only sure way is if adjustment is needed is to remove valve cover

Valves that DON'T need adjutment have NO adjusting screws

There is NO specified check and adjustment interval for 2.5L and 2.8L diesel engines.

Valve clearances (engine at normal operating temp)

2.5L diesel engine- 0.25mm

2.8L diesel engine
Inlet valves- .25mm
Exhaust valves- .35mm

Generally speaking, later models starting with ND automatic trannies DON'T require valve adjustment

Haynes Pajero Repair Manual 1-3 1-17