Maserati 2009 Quattroporte Variator (Cam Phaser) Rattle

Looped 7 times - Can clearly hear the variator (phaser) rattle on start-up.
This happens because the variator is hydraulically operated.
After a few days or even hours oil drains out.
The phaser then rapidly rocks back and forth (rattles) for a moment until it re-pressurizes with oil upon starting.
I fixed mine by adding a Canton oil accumulator which I energize to pressurize the oil galleries (and phaser) before starting.
You can also use a momentary kill switch on the fuel pump - so you crank and pressurize before starting.
Or you can remove the valve covers and the hydraulic actuators and install an anti-drain-back check valve (the official fix).