From 1979 to 1987, Montanu served as project manager at the institute for hydropower studies and projections. Due to having relatives abroad, namely a sister in Germany, Montanu was dismissed from this position in March 1987. After a short series of projects abroad, Montanu returned to Bucharest in September 1989 as an engineering consultant.[2]
In December 1989, during the revolution, Montanu met with Petre Roman, a fellow dissident and one of three leaders in the FSN in the TV station of the central committee. Together, the pair decided upon a message, but due to a failure in equipment, they had to find other means of broadcasting, eventually settling on a broadcasting station belonging to Televiziunea Română (TVR).[3]
Since the revolution, Montanu has worked in the ministry of foreign affairs, with leading positions at the Romanian embassies in Namibia and Malaysia.[4] Later he was summoned to Rio de Janeiro to serve as the General Consul from 2004 to 2010.[5] Whilst in the position, Mihail Monceanu, said that approximately 90% of Romanians in Brazil were Jews and came during the World War II.[6]