Komatsu PC290 NLC overheating problem

Dear, I have problem with Komatsu PC290 NLC producing year 2009, after I start it and work about 15 minutes it overheat, I rest it at low engine speed for 5 minutes and it have normal temperature, but when I start to use machine and work with it it overheat very fast again ? Please help me.

Komatsu PC290 NLC overheating problem