1990 TOYOTA 4RUNNER

Typical onset: 80,000-150,000 mi

Symptoms: White smoke from exhaust, sweet smell, Overheating within minutes of driving, Coolant loss with no visible leaks, Milky oil on dipstick or cap, Coolant in overflow tank pressurizing rapidly

Fix: Factory head gaskets were poorly designed and blow between cylinders. Proper fix requires both heads off, machining if warped (common), upgraded OEM or aftermarket gaskets, new head bolts, timing components, and coolant flush. 12-16 labor hours. Many engines are damaged by the time owners notice, requiring full rebuilds with new pistons, rings, and bearings.

Estimated cost: $2,500-5,000 for head gaskets alone; $4,500-7,500 if engine damage requires rebuild

Typical onset: 100,000-180,000 mi

Symptoms: Transmission fluid leaking near radiator, Pink or red fluid dripping from front of truck, Transmission slipping or delayed engagement after leak starts, Overheating transmission

Fix: Steel cooler lines rust through where they pass the frame or connect to radiator. If coolant mixes with ATF (radiator internal leak), transmission is often toast. External line replacement is 2-3 hours; if internal radiator leak occurred, add transmission rebuild or replacement (8-12 hours).

Estimated cost: $300-600 for lines only; $2,000-3,500 if transmission contaminated

Symptoms: Visible rust-through on frame rails, especially rear crossmember, Rust around body mount points and rear suspension mounts, Soft or flaking metal on frame when probed, Leaf spring mounts separating from frame

Fix: Not mileage-dependent—climate and use driven. Rust-belt and coastal trucks suffer worst. Minor surface rust is normal; structural rust on frame rails or crossmembers often means the truck isn't worth fixing. Frame replacement or professional plating runs 20-40 hours labor minimum.

Estimated cost: $4,000-8,000+ for frame section replacement; total loss if too far gone

Typical onset: 80,000-150,000 mi

Symptoms: Wandering or loose steering on highway, Clunking when turning at low speed, Steering wheel off-center after hitting bumps, Excessive play in steering wheel (more than 1-2 inches)

Fix: The relay rod (center link) and inner/outer tie rod ends wear out, especially on lifted or off-roaded trucks. Full steering refresh includes relay rod, four tie rod ends, alignment. 3-4 hours labor. This was subject to a recall but many weren't fixed.

Estimated cost: $600-1,000

Typical onset: 120,000-200,000 mi

Symptoms: Gear oil dripping from front of rear diff, Oil coating underside of differential and spare tire, Low diff fluid on dipstick check

Fix: Pinion seal hardens and leaks over time. Requires driveshaft removal, pinion nut torque preload reset. 2-3 hours labor. Not urgent unless leaking heavily, but low fluid kills diffs fast.

Estimated cost: $300-500

Typical onset: 150,000-250,000 mi

Symptoms: Rattling or slapping noise from front of engine on cold start, Noise quiets after 30 seconds to 1 minute, Metallic clicking at idle

Fix: Plastic timing chain guides wear and the chain slaps. If caught early, replace guides and tensioner (6-8 hours with cover off). If ignored, chain can jump time or break, bending valves. 22R-E is interference.

Estimated cost: $800-1,400 for guides; $2,500-4,000 if valves bent

Typical onset: 100,000-180,000 mi

Symptoms: No start, cranks but won't fire, Intermittent stalling, especially when fuel tank below 1/4, Loss of power under acceleration or at highway speed, Whining noise from rear of vehicle

Fix: In-tank pump wears out. Requires fuel tank drop or bed removal. 3-4 hours labor. OEM pumps last; cheap aftermarket units fail quickly.

Estimated cost: $500-800