The 1998 Explorer is notorious for transmission failures and SOHC timing chain issues. The 5R55E automatic is the platform's Achilles heel, while the 4.0L SOHC V6 (introduced in '97) has catastrophic timing chain cassette failures that destroy engines.
5R55E Automatic Transmission Failure
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: Harsh 2-3 shift or slipping in 3rd gear, Transmission won't shift out of 2nd gear (limp mode), Burnt transmission fluid smell, Metal shavings in pan during service
Fix: Rebuild or replacement required. Internal clutch packs and valve body are common failure points. Budget 8-12 hours labor for R&R plus rebuild time. Many shops recommend replacement over rebuild due to recurring failures.
Estimated cost: $2,200-3,800
4.0L SOHC Timing Chain Cassette Failure
Common · high severityTypical onset: 100,000-180,000 mi
Symptoms: Rattling noise on cold start that disappears when warm, Check engine light with cam/crank correlation codes, Sudden catastrophic engine failure with metal-on-metal noise, Loss of power and rough running
Fix: The plastic timing chain cassettes disintegrate, allowing chains to jump time and valves to contact pistons. Requires complete timing set replacement with updated metal-backed guides (both sides), new chains, tensioners, and water pump while in there. 12-16 hours labor. If valves bent, add head work or engine replacement.
Estimated cost: $2,500-4,500
Ball Joint and Tie Rod End Wear
Common · high severityTypical onset: 60,000-120,000 mi
Symptoms: Clunking over bumps from front end, Wandering or loose steering feel, Uneven tire wear on inside edges, Vibration in steering wheel at highway speeds
Fix: Lower ball joints wear prematurely, especially with larger tires. Tie rod ends follow close behind. Safety critical—front end can separate. Replace both lower ball joints, inner/outer tie rods, and perform alignment. 4-6 hours labor for comprehensive front end rebuild.
Estimated cost: $800-1,400
Rear Axle Seal and Bearing Leaks
Occasional · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Gear oil dripping on inside of rear tire, Howling or humming from rear differential, Oil spots on driveway under rear axle, Burning smell from oil on hot brake components
Fix: Axle seals leak, contaminating rear brakes. Often the bearing is scored when seal fails. Replace both axle seals and bearings preventively when doing one side. 3-4 hours labor per side. Check pinion seal while in there.
Estimated cost: $400-750
Intake Manifold Gasket Failure (SOHC)
Occasional · medium severityTypical onset: 80,000-140,000 mi
Symptoms: Coolant leaking from front of engine, passenger side, White smoke from exhaust on startup, Overheating with no visible external leaks, Low coolant with no obvious leak source
Fix: Lower intake gasket leaks coolant internally or externally. The SOHC engine requires significant disassembly to access. Replace upper and lower intake gaskets, thermostat, and coolant while in there. 6-8 hours labor.
Estimated cost: $900-1,500
Speed Control Deactivation Switch Fire Risk
Occasional · high severitySymptoms: Cruise control not working, Burning smell near brake pedal area, Smoke from under dash (rare but documented), Brake fluid leaking at master cylinder
Fix: Four separate recalls for speed control systems. The deactivation switch can short and cause fires even when vehicle is parked. Check recall status—many owners never got repairs done. Switch replacement is 1-2 hours labor, but verify recall completion first.
Estimated cost: $0-300
4.0L OHV Head Gasket Failures
Occasional · medium severityTypical onset: 120,000-180,000 mi
Symptoms: White smoke from exhaust, Coolant in oil (milky dipstick), Overheating with bubbles in coolant reservoir, Loss of coolant with no visible leaks
Fix: The older OHV 4.0L is more reliable than SOHC but still sees head gasket failures. Often both sides need work. Resurface heads, new gaskets, timing cover gasket, and coolant flush. 10-14 hours labor for both sides. Cheaper than SOHC engine disasters.
Estimated cost: $1,800-2,800
Hard pass unless it's a low-mileage OHV 4.0L or 5.0L V8 with documented transmission services—the SOHC engine and 5R55E transmission are ticking time bombs that will cost more to fix than the truck is worth.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.