The engine was found to have a leaking valley plate and cam tower cover with little over 82,000 miles on it. An online search indicates that this is a common problem shared across the Lexus (GX460) and Toyota (Tundra) platforms with this engine.

- Charlotte, Nc, NC, USA

The timing cover gasket began to leak oil at 65,000 miles. This is a known manufacturing defect for this engine.

- Simpsonville, SC, USA

10.6.19 radiator blew.while driving.on bridge on interstate. Engine over heated. Engine was supposed to shut down. Engine blew head gasket. Engine light was on from a emission systems recall. I was not aware that engine was over heating. No alerts. Had an appointment on 10.13.19 to fix recalled emissions system. Need new engine and radiator. Cost $10,000 minimium

- Slidell, LA, USA

Lexus GX460 & Toyota 4.6L exhaust manifold cracks and potential carbon monoxide poisoning. The symptoms I identified were a diesel-like clatter on cold start which went away when the engine warmed up. I did feel above normal fatigue when sitting in the car for long periods. My multiple repair attempts with the Lexus dealer should be documented with Lexus. Lexus and Toyota 4.6L V8 exhaust manifolds have chronic cracking problems. These cracks could expose drivers and passengers, including young children, the elderly and people in poor health, to carbon monoxide poisoning when the car is in traffic or stationary with the engine running for long periods of time. It took over 2 years of complaints with my local Lexus dealer and me, the owner, suggesting the 'highly trained and certified Lexus tech' check out the exhaust manifold. It was determined there was a crack. The noise was caused by the crack vibrating/rattling/exhaust gases escaping which reduced the noise after the engine heated up. My concern is the techs did not receive sufficient training to identify a potentisl, Y injurious or fatal problem. The situation is similar to the carbon monoxide issue in law enforcement Ford Explorer. Researching on the internet I identified a large number of complaints from individuals with the 4.6L Toyota V8 engine who also had exhaust manifold cracks. It was also apparent, people with the GX470, the Gx460S predessor, had similar issues with their 4.7L Toyota V8. Unsure if this is a design problem, manufacturing defect or broken quality process with Lexus & Toyota or their vendors.

- Broomfield, CO, USA

Throttle actuator valve stuck open, repaired 3 different times & now secondary air injection system switching valve is stuck open bank 1 car stalls out & goes into limp mode. Check engine light, 4lo, trac light- vehicle is unsafe to drive. Codes P2440 & P2442 this is a faulty part on Toyota Tundra & seqouia.

- Longview, TX, USA