Nine different organisations, including West Midlands Police, the Health and Safety Executive and the Gangmasters and Labour Abuse Authority, took part in the raid this week after wide number of concerns were raised.
However nobody was found at the site and nobody has been arrested over any allegedly illegal activity.
Wolverhampton Council said a variety of health and safety concerns were found including the unsafe storage of metal, lack of limited toilet facilities, blocked fire exits and unsafe electrics.
Pallets and scrap metal were found piled up near engines alleged to have been stolen, while a door marked as a fire escape was also blocked at the yard at Bilston Industrial Estate.
Businesses are believed to have been operating without permits at the yard, the council said, adding that vehicles are thought to have been transporting metal waste to sell at the site without licences.
Photos shared by the council showed pallets stacked on top of a container full of fridges and a warehouse full of car parts, office equipment and gym machines.
The council said there were also concerns over the release of unsafe gases from the many fridges and freezers left inside and outside the buildings.
Further investigations are now planned by the police and other agencies involved.
Inspector Ned Kelly, from Wolverhampton Police, said: “These kinds of premises are simply dangerous. We know illegal activity often takes place in some of them too.
“It was great to be able to work with in partnership with a number of different agencies. Our coordinated approach means we had the right people involved to tackle a wide variety of issues which were found.
“We have excellent working relations with many agencies locally, and work like this really highlights how beneficial it can be.”
As well as Home Office immigration officers, the council said the Refugee and Migrant Centre and British Red Cross were involved to ensure the welfare of any workers at the unit.
Councillor Steve Evans, Wolverhampton Council’s cabinet member for city environment and climate change, said: “This was a complicated and detailed operation co-ordinated by our dedicated Commercial Regulation Service in partnership with a significant number of other agencies.
“The reports on which the operation was based were of huge concern to us and we have acted in a planned and targeted way to determine what exactly is happening at the site.
“I would like to thank our Commercial Regulation Service for coordinating the efforts of all the partners involved.
"I would also like to recognise the support of West Midlands Police, the Environment Agency, Health & Safety Executive and The National Vehicle Intelligence Service. Thanks, should also go to those organisations who attended to offer support to any workers who may have needed it.”
“What was found at the scrapyard premises is now being fully investigated and appropriate action will be taken in due course.”