DETROIT  A successful turnaround without government assistance has lifted the Ford Motor Company’s reputation and raised expectations about the company on Wall Street.

Now Ford, the No. 2 American automaker, is learning that good times can be difficult to manage, too. On Friday, it reported results for 2010, its best year in more than a decade, but investors were disappointed and drove the company’s stock price down 13 percent.

Ford earned $6.6 billion last year, retired more than 40 percent of its debt, and became financially healthy enough to promise $5,000 profit-sharing checks to each of its 40,000 hourly workers in the United States.

But it stumbled in the fourth quarter in Europe and reported relatively flat earnings in North America. Net income in the fourth quarter fell to $190 million, a 79 percent decrease from the same period a year earlier.