A crazed motorist has been filmed revving a chainsaw during a vicious road rage brawl involving four men that disrupted peak hour traffic in Sydney's west.

Dashcam footage shows the moment a shirtless man sprints up to a four-wheel drive that had stopped on Horsley Drive in Fairfield about 5pm on Tuesday.

The man throws punches through an open window as the driver, a 34-year-old man, retaliates by hurling a drink.

Two other men wearing hi-vis shirts are seen running to help the driver as the brawl spills onto the busy road.

The three men eventually subdue the shirtless man before he storms off.

But as the driver of the 4WD climbs back into his vehicle the shirtless man returns to his ute and grabs a chainsaw from the rear tray.

Mobile phone footage aired by the Nine Network showed the man revving the chainsaw as he walked back towards the 4WD - which then drove off - as onlookers screamed.

The shirtless man then retreated to his own vehicle, swearing, before noticing he was being filmed.

"Put your f***ing phone down," he says to the person behind the camera. "Stop recording."

The chainsaw-wielding man's number plate has reportedly been provided to authorities and a NSW Police spokeswoman said local detectives were investigating.

"This type of behaviour is not acceptable in our community under any circumstances," she said in a statement.