On August 15, 1994, at 2135 Pacific daylight time, a Cessna 150M, N714GV, collided with power lines during an attempted forced landing near Mettler, California. The forced landing was precipitated by a loss-of-engine power during cruise. The aircraft was rented from the operator for a personal cross- country flight. Visual meteorological conditions prevailed during the night operation. The aircraft incurred substantial damage. The certificated commercial pilot, the sole occupant, was not injured. The flight originated at Bakersfield, California, on the day of the accident at 2110 as a cross- country flight to San Diego, California. In a Mayday radio call to the Bakersfield Air Traffic Control Tower, the pilot reported a loss of power with a rough running engine. The pilot was given a radar vector toward a private airstrip, but he had insufficient altitude to make the runway. The pilot attempted to make a night forced landing in the center median of an interstate highway and collided with power lines. The aircraft was examined on August 18th by a Federal Aviation Administration (FAA) airworthiness inspector from the Fresno, California, Flight Standards District Office. In his report of the examination, the inspector noted that the right hand heat exchanger internal baffling was deteriorated, allowing stainless steel material to loosen and exit out the exhaust pipe. In the same section of exhaust pipe, a 1/4-inch bolt was installed to retain the pipe on the exhaust assembly. The bolt was found to be a nonstandard installation and protruded 1/2 inch into the pipe forming a restriction. In addition to the exhaust system anomaly, the inspector noted that the number 1 engine cylinder was cracked on the exhaust side of the head. All spark plugs were worn. The right hand magneto was an incompatible model with the Continental O-200 series engines and could not be timed to the engine.