An ambulance broke down on a call to bring a baby to a Dublin hospital and a replacement emergency vehicle also developed mechanical difficulties.
The series of mechanical mishaps resulted in long delays in bringing the baby from Cork to Our Lady's Children's Hospital in Crumlin.
It happened less than a fortnight before an ambulance broke down on Tonlegee Road in Dublin when a paramedic had to break a window to help get a child out of that vehicle.
This latest revelation involving ambulance failure has sparked warnings that a lack of investment in new ambulances could be endangering patients' lives.
"It's completely unacceptable that ambulance services are under-funded and under-resourced which could be putting lives at risk," said Fianna Fail health spokesperson Billy Kelleher.
He told the Irish Independent: "A full audit must be done on the age profiles of ambulance vehicles to allay the fears of the public."
The Health Service Executive confirmed that a neonatal ambulance broke down on its way to Cork to bring a baby from Cork University Hospital to Crumlin.
A second ambulance also developed problems and it was at least five-and-a-half hours until the baby arrived at hospital in Dublin.
A source in the ambulance service said the second vehicle "limped back to Dublin but they got the baby to the hospital".
This second ambulance had to stop to remove an incubator from the broken-down ambulance near Mitchelstown before continuing to Cork. The source said the neonatal ambulance is nearing the end of its life as it has in the region of 360,000km on its odometer.
The HSE said "the only vehicles planned to be purchased in 2014 are emergency ambulances"; it did not say whether a new neonatal ambulance would be one of them.
A HSE spokeswoman confirmed the neonatal ambulance was asked to go to Cork University Hospital "to transport a neonate back to Dublin".
She said the ambulance departed the Rotunda Hospital at 6.35pm on March 3 but developed "a mechanical problem" near Mitchelstown, Co Cork.
A medical team that had travelled with the ambulance was brought to Cork University Hospital.
She said "the second vehicle developed difficulties in the early hours of March 4".
John Kidd, chairman of the Irish Fire and Emergency Services Association, said he was "not surprised" by yet another case of ambulance mechanical difficulties as there has been insufficient investment in replacement ambulance vehicles.
"There should be no skimping on ambulance resources. Adults and children will suffer unless there is adequate investment," said Mr Kidd.