Mr Stein's departure is not thought to be imminent, and may not take place until next year, according to insiders.
Under his leadership and that of Mike Turner, GKN's chairman, the company has enjoyed a strong recent run, with its shares buoyed by a pledge to increase defence spending by Donald Trump, the new US President.
The search for Mr Stein's successor means that a handful of Britain's biggest industrial names will all have replaced their chief executives within a roughly two-year period.
Cobham and Rolls-Royce, which have both been hit by a string of profit warnings, BAE Systems and Babcock International have also installed fresh leadership during that period.
Mr Stein joined the company in 1994, working his way up through roles including group finance director and chief executive of its automotive division, before landing the top job five years ago.
The company, which operates in the automotive and aerospace sectors, has long been touted as a takeover target for a foreign predator.
It makes wing components through its Fokker division, and supplies components used in roughly half of the world's cars.
Its large pension deficit has, however, acted as a poison pill deterrent to a potential bidder, or a possible break-up of the company.
Mr Turner, who will lead the search for Mr Stein's successor, is expected to look at both internal and external candidates for the job.
GKN, shares in which are up more than 30% during the last year, giving it a market value of £6.35bn, declined to comment on Wednesday night.
SKY News.