2001 FORD EXPEDITION

Typical onset: 80,000-150,000 mi

Symptoms: Sudden loss of power with loud popping or hissing sound, Misfire code on one cylinder, Spark plug physically blown out of cylinder head with threads stripped

Fix: The 2-valve 5.4L has inadequate thread engagement—only 4 threads holding the plug. When it blows, you need a HeliCoil or TimeSert thread repair kit (2-3 hours per plug if accessible). If multiple cylinders are affected or head damage is severe, you're looking at cylinder head removal and machine work (12-16 hours labor). Some shops proactively install inserts during plug changes.

Estimated cost: $500-1,200 per cylinder for insert repair, $2,500-4,000 if head removal required

Typical onset: 90,000-140,000 mi

Symptoms: Transmission fluid in coolant overflow (strawberry milkshake appearance), Erratic shifting or slipping after coolant contamination begins, Overheating transmission, burnt fluid smell, Total transmission failure if coolant mixes into valve body

Fix: The internal cooler in the radiator fails, allowing coolant into the transmission or vice-versa. Once contaminated, the 4R100 needs complete rebuild or replacement (8-12 hours), plus new radiator (2-3 hours), full cooling system flush, and all cooler lines replaced. This is a known design flaw—aftermarket external coolers are mandatory prevention.

Estimated cost: $3,500-5,500 for transmission rebuild/reman + radiator + lines

Typical onset: 70,000-120,000 mi

Symptoms: Coolant smell in cabin or under hood, Slow coolant loss with no visible external leak, White smoke on cold start, Coolant puddle under intake valley after sitting

Fix: Plastic intake manifolds crack at the crossover or the gaskets fail. Requires intake removal, new manifold or gaskets, coolant flush (6-8 hours labor). The 5.4L is more prone due to higher heat. Some techs upgrade to aluminum aftermarket intakes during the repair.

Estimated cost: $800-1,400

Typical onset: 80,000-130,000 mi

Symptoms: Clunking noise over bumps from front end, Loose or wandering steering feel, Uneven tire wear on inside edge, Visible play when prying on control arm

Fix: Upper and lower ball joints wear out, especially with oversized tires or towing. Ford uses riveted joints—replacement requires drilling out rivets and pressing in new joints or replacing entire control arms (3-5 hours per side). Alignment mandatory after. Do both sides at once.

Estimated cost: $600-1,200 for both sides with alignment

Typical onset: 100,000-180,000 mi

Symptoms: Loud ticking or exhaust leak sound from engine bay, especially on cold start, Exhaust smell in cabin, Visible cracks near center ports of manifold

Fix: The 5.4L cast iron manifolds crack from heat cycling, typically passenger side first. Manifold replacement requires removing multiple accessories (4-6 hours per side). Studs often break during removal, adding time. Dorman makes affordable replacements, but OEM lasts longer.

Estimated cost: $600-1,000 per side

Typical onset: 90,000-150,000 mi

Symptoms: Vibration or shudder during light acceleration at 35-45 mph, Feels like driving over rumble strips, Worsens when transmission is hot, No codes, shifts otherwise normal

Fix: Torque converter clutch material deteriorates, causing lockup shudder. Fresh fluid and additive sometimes helps temporarily, but permanent fix is converter replacement which requires transmission removal (8-10 hours). While it's out, replace rear main seal and flex plate if needed.

Estimated cost: $1,800-2,800

Typical onset: 100,000-160,000 mi

Symptoms: Gear oil on inside of rear wheel or brake drum/rotor, Grinding or howling noise from rear axle, Low differential fluid level

Fix: Axle seals leak, contaminating brakes. If bearing is also bad, requires axle shaft removal, new seal, and possibly new bearing (2-3 hours per side). Cheap fix if caught early, but leaked fluid ruins brake shoes/pads. Check diff fluid regularly.

Estimated cost: $300-600 per side