On June 7, 2003, at 0745 central daylight time, an amateur-built Glastar, N109BZ, piloted by a private pilot, sustained substantial damage when it nosed over during a precautionary landing near Pierce, Nebraska. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 without a flight plan. The pilot was uninjured. The local flight departed at 0720. The purpose of the flight was to test the airplane's engine in the traffic pattern. The pilot reported he entered the downwind leg and the engine temperature rose to 260 degrees Fahrenheit (F). The pilot stated he "had a choice [to] continue around the pattern with an overheating engine, or land immediately directly into a 15 [mile per hour] headwind, in a flat meadow [with] 12 inch tall grass." The pilot reported he chose to land in the meadow rather than continue on downwind and land on the mowed grass airstrip. The pilot reported the nose gear became stuck in the tall grass during landing rollout and the aircraft nosed over. The pilot reported the airplane had flown a total of 8.6 hours since receiving an Federal Aviation Administration (FAA) airworthiness certificate. He reported he had experienced trouble with the engine cooling system on previous flights. The pilot stated the engine's maximum temperature is 230 degrees F. The pilot indicated he had experienced engine temperatures between 250 and 260 degrees F while at low airspeeds, idling, or during taxi tests. The pilot stated, "In hindsight, I wish I wouldn't have flown with a questionable engine, but I figured I had to get [the airplane] in the air and get more air going through the radiators to test [the engine's] cooling abilities." A FAA airworthiness inspector conducted an on-scene inspection of the airplane. The inspection revealed engine and control surface continuity. The inspection of the engine cooling system did not reveal the reason for the high engine temperatures.