The reciprocating head pipe is a very promising technology in engine piston cooling, especially far heavy-duty diesel engines. The concept of the reciprocating heat pipe is verified through the experimental observation of a transparent heat pipe and by thermal testing of a copper/water reciprocating heat pipe. A comparative thermal analysis on the reciprocating heat pipe and gallery cooling systems is performed. The approximate analytical results show that the piston ring groove temperature can be significantly reduced using heat pipe cooling technology, which could contribute to an increase in engine thermal efficiency and a reduction in environmental pollution.