2024 LEXUS IS 350

Typical onset: 60,000-90,000 mi

Symptoms: rough idle, especially cold start, misfires under load, reduced throttle response, check engine light with multiple misfire codes

Fix: Walnut blasting the intake valves is the proper fix. Takes 4-6 hours labor to remove the intake manifold, blast all six cylinders, and reassemble. Some shops try induction cleaning sprays first but results are temporary at best.

Estimated cost: $600-1,200

Typical onset: 70,000-120,000 mi

Symptoms: transmission fluid drips near front of engine, low fluid level on dipstick, harsh shifting or slipping if fluid gets very low, burnt ATF smell

Fix: The cooler lines that run to the radiator crack at the crimp fittings or corrode through. Replacement is 2-3 hours — need to lift the car, drain some coolant, replace both lines as a set. Critical to catch early before the trans runs low on fluid and damages clutch packs.

Estimated cost: $400-800

Typical onset: 80,000-130,000 mi

Symptoms: coolant leak from front of engine, squealing or grinding noise from accessory belt area, overheating, coolant in the oil (catastrophic bearing failure mode)

Fix: The 2GR water pump is buried behind the timing cover. It's a 6-8 hour job: timing cover off, new pump, new timing cover gaskets, new coolant. Always replace the thermostat and hoses at the same time since you're in there. If the bearing fails completely, coolant mixes with oil and you're looking at engine damage.

Estimated cost: $1,200-2,000

Typical onset: 100,000+ mi

Symptoms: rattling or ticking noise at cold start for 2-5 seconds, noise disappears once oil pressure builds, no performance issues or check engine light

Fix: The variable valve timing gears wear and develop internal play. It's mostly a nuisance noise. Fix requires 8-10 hours: valve covers off, timing cover off, replace all four VVT gears and the timing chain while you're in there. Most owners live with the noise unless selling the car.

Estimated cost: $1,800-3,000

Typical onset: 60,000-100,000 mi

Symptoms: clunk when shifting from Park to Drive or Reverse, vibration at idle in gear, excessive drivetrain movement felt through the cabin

Fix: The rear transmission mount (also called the pitch stop) is a fluid-filled design that fatigues and collapses. Replacement is straightforward: 1-1.5 hours with a lift. OEM mount is pricey but aftermarket options exist. Improves shift feel noticeably.

Estimated cost: $300-600

Typical onset: 50,000-90,000 mi

Symptoms: vibration or shudder during light acceleration at 25-45 mph, feels like driving over rumble strips, worse when transmission is hot or under load

Fix: Toyota's 8-speed in the IS can develop torque converter lockup clutch shudder, often related to ATF degradation. First step: drain and fill with fresh Toyota WS fluid (4-5 quarts, repeat 2-3 times to flush). If that doesn't fix it, you're replacing the torque converter, which is 8-10 hours with trans removal. Some cases need valve body updates too.

Estimated cost: $400-800 for fluid service, $2,500-4,000 for torque converter replacement