An ambitious restoration project to revive the historic Great Melbourne Telescope (GMT) in time for its 150th anniversary is running out of time and money.

A team of devoted volunteers has spent eight years helping to bring the astronomical treasure back to life, but more help is needed if the GMT is to be ready by 2019.

Once the largest fully steerable telescope in the world, the GMT was built in Dublin and erected at the Melbourne Observatory in 1869.

Astronomer Jim Pollock works to restore the GMT every Wednesday. ( ABC News: Michael Barnett )

It became a symbol of "marvellous Melbourne" when a young, ambitious colony reached for the stars.

Housed on the edge of Melbourne's Royal Botanic Gardens, for decades it was used to explore the southern skies.

By the 1940s it fell into disuse and was transferred to the Mt Stromlo Observatory near Canberra, where it was remodelled and repurposed for new astronomical projects.

Many of the original smaller parts, like the metal mirror and eye pieces, were stored in a Museum Victoria warehouse.

In 2003, fierce bushfires swept through parts of Canberra, destroying all the major telescopes on Mt Stromlo.

Museum Victoria, the Astronomical Society of Victoria and the Royal Botanic Gardens agreed to work together with Mt Stromlo Observatory to return the GMT's remains to Melbourne.

Volunteer astronomers piece together telescope

Since 2008, volunteer astronomers have been working alongside curators every Wednesday at the museum warehouse in Melbourne's north, which they describe as "the best men's shed in Victoria".

The Great Melbourne Telescope in the early 1900s. ( Supplied: State Library of Victoria )

"Most of us are retired. It's like Dad's Army goes to play group," astronomer Jim Pollock said.

Without the original designs, the rebuilding process is painstaking, detailed and exacting, relying on technical expertise and massive devotion.

"It's measuring every bolt and recording that, and measuring every component," Neville Quick from Museum Victoria said.

"It's not romantic, but by gee it's important. It's a beautiful piece of Victorian engineering; a really major piece of scientific heritage of Melbourne, Victoria, Australia, the world."

The project is seeking a financial injection to help pay for crucial parts like a new mirror costing around $500,000.

"Maintaining a positive attitude and enthusiasm over more than eight years is a pretty hard thing to keep up, sadly even some of us have died," Mr Pollock said.

"We have no government support, we've got no corporate support yet," he said.

"We hope that as more and more people and companies realise what we are doing they will support us.

"If the Melbourne City Council would come to the party, it would make the job a lot easier and give us fresh hope that we could do it."

Royal Botanic Gardens CEO Tim Entwisle said the GMT had enormous educational and tourism potential.

"I want this to be the focus of a new science precinct," he said.

"By bringing this telescope back to the botanic gardens we are not only going to recreate a bit of history, the bit that we thought was gone forever, but it's a really great opportunity to bring together botany, astronomy, meteorology, all those sciences to do with the natural world," he said.

"This is a unique opportunity because those things don't exist together in many places in the world."

Astronomical society volunteers (LtoR) Jim Pollock, Graeme Bannister, Mal Poulton, Dr Barry Clark, Ian Barry, Barry Cleland, John Cavedon and Bryan Mooney. ( ABC News: Michael Barnett )

ABC cameraman Michael Barnett has spent eight years documenting the GMT restoration project. Watch the story on Australia Wide, 11:30am Saturday on News 24, 10:30am Sunday on ABC1, and ABC iView.