Toyota VZ (3VZ-E / 5VZ-FE)

Toyota's V6 before the GR — the 3.0 3VZ-E and the 3.4 5VZ-FE — in the 4Runner, T100, Tacoma, Tundra and Previa. The two have opposite reputations and it is worth knowing which is which.

The 3VZ-E is the one with the head gasket problem, and it was widespread enough that Toyota extended coverage. Coolant loss and overheating on a 3.0 of that era points there first, and by now the question is whether it has already been done rather than whether it will happen.

The 5VZ-FE is the opposite — one of the most durable engines Toyota has built, and the reason so many high-mileage Tacomas and 4Runners are still working.

Both are belt-driven and non-interference, which is the single most useful thing to know about them: a snapped timing belt strands the vehicle and does not bend the valves. That changes the calculation on a cheap example with no belt history entirely — and it is the opposite of most of their contemporaries.

The water pump is driven by the timing belt, so the two are replaced together as a matter of course. A pump changed on its own means the belt has been disturbed and not renewed, which is worth asking about.