The 2000 Explorer is notorious for catastrophic transmission failures and SOHC timing chain cassette issues. These two problems alone have defined this generation's reliability reputation, with the 5R55E transmission being particularly fragile under normal use.
5R55E Automatic Transmission Failure
Common · high severityTypical onset: 80,000-130,000 mi
Symptoms: Harsh or delayed 2-3 shift, especially when cold, Transmission slipping in overdrive or under load, Complete loss of forward gears, reverse still works briefly, Burnt fluid smell, dark brown or black ATF
Fix: Forward clutch drum and coast clutch failure are epidemic. Cooler line corrosion contaminates fluid. Rebuild requires 12-16 hours; most shops recommend replacement with remanufactured unit (8-10 hours). External cooler addition is mandatory to prevent repeat failure.
Estimated cost: $2,200-3,800
4.0L SOHC Timing Chain Cassette Failure
Common · high severityTypical onset: 100,000-160,000 mi
Symptoms: Cold-start rattle from front of engine for 2-5 seconds, Check engine light with cam/crank correlation codes (P0340, P0344), Sudden catastrophic failure: bent valves, no start, Metal shavings in oil, timing cover area noise
Fix: Plastic cassette guides disintegrate, chains jump time. Requires both primary and secondary chain cassettes, tensioners, guides, and variable cam timing (VCT) solenoids. 14-18 hours labor. If valves are bent (50/50 chance if it jumps), add heads and gaskets.
Estimated cost: $2,800-4,500
Rear Axle Bearing and Seal Leaks
Common · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Gear oil dripping on inside of rear tire/wheel, Howling or grinding noise from rear, worse in turns, Visible leak at axle tube where it meets backing plate, Low differential fluid level on dipstick
Fix: Axle shaft seals fail, allowing gear oil past. Often the bearing is damaged by the time owner notices leak. Requires axle shaft removal, new bearing and seal, sometimes axle shaft replacement if splines worn. 3-4 hours per side.
Estimated cost: $450-850
Upper and Lower Ball Joint Failure
Common · high severityTypical onset: 70,000-110,000 mi
Symptoms: Clunking over bumps from front suspension, Wandering or loose steering feel, Excessive tire wear on inside or outside edge, Visible play when prying on wheel with vehicle lifted
Fix: Both upper and lower ball joints wear, lowers fail more catastrophically. These are riveted from factory; replacement requires drilling out rivets and bolting in new joints or replacing entire control arms. 4-6 hours for both sides with alignment.
Estimated cost: $800-1,400
Intake Manifold Runner Control (IMRC) Sticking
Occasional · low severityTypical onset: 60,000-120,000 mi
Symptoms: Check engine light P1406 or P1407 (IMRC monitor), Slight hesitation or stumble around 3,000 RPM, Reduced power at highway speeds, Rattling from intake manifold area on startup
Fix: Butterfly valves in lower intake stick from carbon buildup or broken actuator rods. Can sometimes be freed with intake cleaner through throttle body. Full fix requires lower intake removal, cleaning, and actuator replacement. 4-5 hours.
Estimated cost: $450-750
Fuel Pump Driver Module Failure
Occasional · medium severityTypical onset: 80,000-140,000 mi
Symptoms: No-start condition, engine cranks but won't fire, Stalling after warmup, especially in hot weather, Intermittent loss of fuel pressure, Module mounted on frame rail gets corroded
Fix: Driver module behind rear bumper on frame fails from corrosion or heat. Often misdiagnosed as fuel pump. Module replacement is 1-2 hours. If pump is also weak, budget for both (pump is 3-4 hours with tank drop).
Estimated cost: $250-450
Hard pass unless under $2,000 and you can wrench yourself — transmission and timing chain repairs will exceed vehicle value for most examples.
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.