There is two ways to fix it; one is to upgrade the sintered gear in the oil pump with a billet one and the second is to change the crankshaft pulley with a Fluidampr or another harmonic dampening pulley spec'd for a 2zz engine. They're almost mutually exclusive solutions, and I chose the oil pump gear upgrade for two reasons:
1. I had purchased from Toyota a new pump to install
2. I had already purchased from Eliseparts an oil pump gear
This is how I did it and found it the best way to replace the gear without causing damage to the Philips screws holding the pump shell together.
Apart from a new Toyota oil pump (recommended, as any aftermarket billet gear is machined and toleranced against brand new assemblies) and a billet gear of your choice (Toda, Eliseparts, MWR etc) you need the following tools and process steps to complete the job.
1x long ratchet (you'll need all the torque you can get!)
1x suitable adapter for screwdriver bits for the ratchet
1x hammer (YES! HAMMER!)
1x vice ( in a pinch, a friend holding the pump can also help )
1x the biggest/fattest Philips screwdriver bit in your kit
- Start by placing the screwdriver bit on the screw head and hit it hard with a hammer until it's solidly in place.
- With the pump secured on a vice (or with a help of a friend holding it completely flat), attach the ratchet and rotate counter-clockwise to undo the screws
- Remove sintered oil pump gear and replace with billet
- Assemble the pump and tighten the bolts as much as practically possible (avoid damaging the bolts heads)
It's a quick job, the only tricky bit is those Philips screws holding the pump together.
I hope you find this useful. Any questions on this, fire away