RAILWAY volunteers are still steaming at the ears, as they step up their campaign to secure a serviceable diesel locomotive to back-up their broken down steam train.

Members of the Southern Downs Steam Railway have been left furious after five years of searching for a diesel locomotive has again fallen on deaf ears, this time leaving the group off the tracks indefinitely.

A tour to Wallangarra had been scheduled for tomorrow, but was cancelled on Thursday after a steam leak forced the group's popular steam train off the tracks.

Southern Downs Steam Railway president Peter Gregory said he was frustrated by the situation.

"We're just banging out heads against a brick wall," he said.

"Every time we ask for a diesel locomotive we get knocked back."

Queensland Rail and Aurizon both use the diesel locomotives which the Southern Downs Steam Railway are chasing.

Committee member Bob Keogh said there were plenty of the 1700 class diesel locos in Queensland.

"We have got to have a diesel here at all times," he said.

"Down at the Ipswich workshop there is a shed full of old locomotives.

"When we ask for one they say 'sorry we don't have anything'."

While a diesel locomotive wouldn't be exactly the same as a steam engine tour, it could be used as a back up in the instance of the regular breakdowns which the group have grappled with over the years.

Mr Keogh told the Daily News the current steam loco was in fair condition, but was over worked.

"If it did half the work it would last us twice as long," he said.

"In the old days you could just go next door and use a spare steam train, but it's not the case anymore."

The group estimate a new diesel locomotive would set them back between $20,000 - $80,000, though money was the least of their concerns.

"I don't give a damn if we own it or not," Mr Keogh said. "We'll buy it or we'll lease it - we just can't go on without one."

Aside from being used to assist in the event of a breakdown, a diesel engine would prove beneficial in a number of situations.

"The good thing with a diesel is you can go from here to Stanthorpe without having to go and turn around in Wallangarra," fitter John Brady said.