At 16:33 CDT, a Mooney M20F lost engine power near Tomball and was damaged in the forced landing. The pilot suffered a minor injury and the passenger was not injured. The airplane was climbing through 4,000 feet on an IFR flight plan from Conroe to San Marcos, Texas, when the engine rpm increased and the engine oil pressure dropped to zero. The pilot was vectored toward Hooks Airport but landed in a field short of the runway. Examination of the engine revealed the No. 4 connecting rod sticking out of the crankcase.