An initial investigation into a potential leak of toxic chemicals at a Sydney housing estate has cleared the site of "significant contamination", more than three years after the possible safety risk to thousands of residents was first recognised.

Since 2015, Ford Motoring Company suspected chemicals, including ammonia, could have spread from a former waste dump at its old factory to the residential precinct at Centenary Park in Homebush West.

Centenary Park estate at Homebush West is home to about 2500 residents. Credit:James Brickwood

But the Herald revealed earlier this year that the extent of any contamination from the former landfill site remained unknown.

That was because Ford and the developer, Telmet Ventures, had been locked in a dispute over Ford's access to test for the presence of any chemicals on the site.