One problem related to engine rattling and whining sounds has been reported for the 2003 Nissan Altima. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Nissan Altima based on all problems reported for the 2003 Altima.
While driving on the highway, engine began to make rattling noise and lost a significant amount of power during acceleration. Due to location and time of night, I coasted (barely using any acceleration) to a safe location. Turned engine off to look under the hood- could not find any problem. Tried starting car again and would not start. Had it towed the next day to mechanic- he found shards of metal in the engine oil and stated that the valves screws had came off and ruined the engine. I had always put in synthetic oil every 5k miles, and did a complete engine flush every year/25,000 miles ever since I bought the car 6 years ago. This occurred at 133500 miles and the engine cannot be salvaged. To replace the engine, the estimates I am receiving are between 2,000 and 3,000 usd.