(July 7, 2010) Several news sources including Bloomberg News have reported that Toyota received complaints more than three years ago about engine problems that sparked recalls this week of more than 270,000 Lexus and Toyota vehicles in Asia and North America.

The National Highway Traffic Safety Administration on Tuesday released Toyota's "Defect Information Report" on the vehicles affected by the recall.

In the report, Toyota said it monitored U.S. field technical reports from March 2007 to August 2008.

"The number of reports of broken valve springs was relatively small, and the vast majority reported abnormal engine noise, rough engine performance, and no start conditions readily noticeable to vehicle operators," Toyota said in the four-page report.

Toyota said it received no reports of any crashes or injuries. But beginning in October 2009, the automaker received an increasing number of reports of "total engine failure" and of broken 3.3 mm diameter valve springs, according to the report.

On July 1, Toyota said it decided to recall the Lexus vehicles following an investigation that found "a possibility that the strength of valve springs with a wire diameter of 3.3 mm may be degraded by a micro-foreign object in the material of the valve spring, causing the spring to break."

About 138,000 vehicles in the United States may be affected, according to the Toyota City, Japan-based company.

In Japan, the carmaker received the first customer complaints in March 2007 in Japan regarding defective valve springs that may cause engines to stall, Toyota spokeswoman Ririko Takeuchi said Tuesday. The recall in Japan covers cars built between July 2005 and August 2008.

The problem occurs when foreign substances enter the material used to make the part, causing the spring to weaken and break, Tokyo-based spokeswoman Monika Saito said. While Toyota decided to address the problem in August 2008 by altering the design of the valve spring and making it thicker, the company didn't feel that a recall was necessary given the rarity of the problem at the time, she said.