Toyota built the 3.4 liter V6 with a cast iron block and aluminum head, using a dual overhead cam valve system and sequential 1-2-3-4-5-6 firing order. The engine had a 9.6:1 compression ratio and was used in Land Cruiser, Tacoma, HiLux, 4 Runner, Tacoma, Tundra, T-100, and Granvia models during its 9-year production run.
It was based on the 3VZ-FE 3.0 liter V6 and shared the same block, although the cylinder bore was increased from 87.4mm to 93.5mm. The camshaft and intake and exhaust manifolds were redesigned to produce more torque in the lower rpm range, making the engine better for rock crawling and meandering along wooded trails.
The fuel injection and ignition systems were also upgraded, and the 3.4 liter V6 got an oil cooler and more powerful radiator fan to help prevent overheating at low speeds and during other situations where airflow to the front of the vehicle might be restricted.
Despite occasional problems with head gasket failure that could lead to coolant loss and overheating, a properly lubricated and maintained 5VZ-FE 3.4 liter V6 can last more than 200,000 miles. After 2004, it gave way to the 1GR-FE 4.0 liter V6.
