By Ernest Scheyder

(Reuters) - Caterpillar Inc uncovered a "deliberate, multi-year, coordinated accounting misconduct" at a subsidiary of a Chinese company it acquired last summer, leading it to write off most of the value of the deal and wipe out half a quarter's profits.

Caterpillar, the world's largest maker of tractors and excavators, said on Friday it would take a noncash goodwill impairment charge of $580 million, or 87 cents per share, in the fourth quarter of 2012.

Analysts had expected the company to earn $1.70 per share in the fourth quarter, according to Thomson Reuters I/B/E/S.

Caterpillar closed the purchase of ERA Mining Machinery Ltd and its subsidiary Siwei last June, paying HKD5.06 billion, or $653.4 million at current exchange rates.

A member of the Caterpillar board during the course of the Siwei deal told Reuters the board was distracted at the time by a larger transaction and paid relatively little attention to the Siwei acquisition.

In a statement, Caterpillar said an ongoing investigation launched after the deal closed "determined several Siwei senior managers engaged in deliberate misconduct beginning several years prior to Caterpillar's acquisition of Siwei."

The company said it had replaced several senior managers at Siwei, adding that their conduct was "offensive and completely unacceptable."

Caterpillar was not immediately available for further comment.

Representatives for Siwei were not immediately available for comment before business hours on Saturday morning in China.

(Reporting by Ernest Scheyder; Writing by Ben Berkowitz; Editing by Gary Hill)