2004 LEXUS GX 470

Typical onset: 80,000-150,000 mi

Symptoms: Check engine light for air injection codes, Failed emissions testing, Rough cold starts in some cases, Rattling from engine bay on cold start

Fix: The air injection pump, vacuum switching valve, and associated hoses fail from heat and age. Most owners delete the system entirely (not legal everywhere) or replace the pump and valves. Pump replacement is 2-3 hours labor, full system refresh can be 4-5 hours with hoses and valves.

Estimated cost: $800-1,800

Typical onset: 100,000-180,000 mi

Symptoms: Transmission fluid leaking at radiator area, Transmission overheating, Delayed or harsh shifting, Milky fluid if cooler fails internally and coolant mixes with ATF

Fix: The factory transmission cooler lines rust through where they pass the frame, and the internal radiator cooler can fail allowing coolant contamination. External leak fix is 2-3 hours for lines. Internal cooler failure requires radiator replacement, full transmission fluid flush, and often transmission rebuild if contamination went unnoticed. Many add an external cooler as preventive measure (1.5 hours).

Estimated cost: $400-900 for lines alone, $3,000-6,000 if coolant contaminated transmission

Typical onset: 80,000-140,000 mi

Symptoms: Clunking over bumps from front end, Wandering or loose steering feel, Uneven tire wear on inside edge, Play in wheel when lifted and checked

Fix: The lower ball joints wear out and can separate catastrophically, causing loss of control. Toyota issued TSB and revised parts. Requires pressing out old joints or replacing entire lower control arms (easier method). 3-4 hours per side with alignment. Some shops won't press due to liability and insist on complete arm replacement.

Estimated cost: $800-1,400 for both sides with arms

Typical onset: 150,000-250,000 mi

Symptoms: Sudden severe knocking or rattling, Oil pressure warning light, Metal shavings in oil, White smoke from exhaust initially, then blue/black, Seized engine in worst cases

Fix: A documented design weakness in early 2UZ-FE pistons causes the ring land to crack and collapse, dropping debris into the cylinder. This scores cylinder walls and spins rod/main bearings. Once it starts, the engine is done. Requires short block replacement minimum, often full rebuild or replacement long block. 18-25 hours labor for in-chassis rebuild with machine work, 12-16 hours for replacement long block.

Estimated cost: $5,500-9,000 for rebuild, $7,000-11,000 for replacement long block installed

Typical onset: 90,000 mi intervals

Symptoms: Whining from front of engine (water pump bearings), Coolant leak at water pump weep hole, Squealing belt noise, Catastrophic failure if belt breaks - bent valves

Fix: The 2UZ-FE is an interference engine. If the timing belt breaks, valves hit pistons causing major damage. Factory interval is 90k miles but many go longer. Smart practice is replace belt, water pump, tensioner, and idler pulleys as a kit. 4-6 hours labor depending on AC and other accessories.

Estimated cost: $800-1,400

Typical onset: 100,000-160,000 mi

Symptoms: Clunking on acceleration or deceleration, Vibration at highway speeds, Squeaking from underneath while driving, Visible rust or play in driveshaft joints

Fix: The two-piece front driveshaft develops play in the U-joints and center support bearing. Can cause vibration and eventually catastrophic failure if ignored. Driveshaft removal, U-joint pressing, and reinstallation is 2-3 hours. Some replace entire driveshaft assembly instead of rebuilding.

Estimated cost: $400-800

Typical onset: 120,000-180,000 mi

Symptoms: Coolant smell in cabin, Coolant loss with no visible external leak, Wet carpet on passenger side, Overheating if leak is severe

Fix: A plastic T-valve under the intake manifold cracks and leaks coolant. Accessing it requires removing the intake manifold and various lines. 6-8 hours labor due to location. Often discovered during other engine work. Should replace all coolant hoses in area while in there.

Estimated cost: $800-1,400