The family had climbed about 10m down the bank, finding bits and pieces that looked to be from a car.
"There was one part where I was always fixing dad's back door, putting a panel on the back door. I found that," son Selwyn Koia said yesterday as they waited for the dive squad to arrive.
A jetboat went around in the morning but the water was too deep for anything to be seen. Mr Koia's car was found by a search and rescue team in the river about 1.30pm.
"I know he's gone," Selwyn said before the car was found. "It's something you can't talk about but you feel it."
Detective Brett Humphrey said family had begun to worry about Mr Koia when he left to take his car into Wanganui for a service and never got there.
The great-grandfather lived by himself.
Selwyn described his father as a "very humble man", highly respected by those around him.
"To me he was a really good father. He taught us a lot - there's stuff you don't find in a dictionary, you can't find in a library to read about. Knowledge within himself about life.
"A lot of people go to him and ask about knowledge of a lot of things."
Joe Koia had been at Pipiriki for more than 20 years and was the kaumatua there, his son said. He had six sons and one daughter, although Selwyn was the only biological child.
He had previously lived in Waipukurau in Hawke's Bay and had been an elder at the Manu Ariki Marae.
Driver dies in accident
Wanganui man Shane Edgecombe, 20, died in a single-vehicle crash on State Highway 3 near Bulls yesterday morning.
A member of the public contacted emergency services after spotting a vehicle in a ditch. While a scene examination had been completed, the crash investigation was ongoing.
It was unclear what caused the crash, Manawatu police said.