The 2021 Ford Explorer engine complaints span multiple, distinct failure modes affecting reliability across the board. Most concerning are catastrophic engine failures: complete seizure, metal debris in oil pans, failed valve keepers (dropping intake valves into cylinders), dropped valve springs, and bearing failure. These typically require full engine replacement at $11,000–$12,000. Failures occur at surprising low mileages—15,500 miles, 31,000, 45,000—with little or no warning light. One owner reports a valve keeper failure that destroyed both turbos, the flywheel, and torque converter; another cites bearing failure at 4 years old after knocking noises preceded any dashboard warning.
Catalytic converter cracking and exhaust flex pipe separation are epidemic, occurring at 53,000–89,000 miles with loud banging and rattling. Fuel diluting the crankcase oil to dangerous levels is documented—1.5 quarts of fuel mixing in within 1000–1500 miles of driving, with dealers confirming no fix exists yet and warning of eventual engine destruction.
Oil leaks from intermediate shaft seals and the plastic pan are slow but persistent; one starts at one drop per day. Coolant intrusion into oil is reported, contaminating bearings. One post-replacement engine continues smoking on cold start with no diagnostics available.
Ford issued technical service bulletins and recalls (21E11, 24V635000, 24S55, 24V598000), but many affected VINs fall outside coverage windows or were built within campaign dates but excluded from parts lists. Dealers consistently report known issues while declining warranty repair.
Failure modes owners describe
Engine oil leaks (intermediate shaft seals and pan)
Oil leaking from intermediate shaft, seals, or plastic oil pan sealings. Ford dealerships have acknowledged the issue and documented ongoing leakage. Ford declined warranty repair on at least one vehicle. Fluid loss risk and potential hot-engine contact hazard.
When: Starting early in ownership; first noted in November for one vehicle; occurs at multiple mileages
Symptoms owners cite: Oil dripping or weeping from engine/drivetrain area; Visible oil on underside
Repairs/costs cited: Ford dealership service visits documented the issue; manufacturer declined repair citing warranty status
Recalls/TSBs owners mention: Ford technical service bulletins exist for intermediate shaft and related seals; warranty repair declined
Catalytic converter cracking/failure and exhaust detachment
Catalytic converters fracture at welds or separation points; exhaust pipes detach from converters or rust and separate. One report of attempted converter theft contributing to damage. Dealers attributed some failures to rust or theft attempts, but owners and Service Program 21E11 suggest design/manufacturing defect.
When: Various mileages: 53,300; 58,691; 89,000; 60,000 miles noted
Symptoms owners cite: Loud banging or rattling noise from undercarriage; Exhaust odor; Motorcycle-like exhaust sound; Abnormally loud sound at idle; Loss of power
Codes mentioned: Catalytic converter code
Repairs/costs cited: Some referred to muffler shops; customers declined repair due to cost. One involved theft attempt complication.
Recalls/TSBs owners mention: Ford Campaign/CSP 21E11 (Emission Recall - Engine); 21B35 (Certain 2020 MY Police Explorers); customers noted they were ineligible or unable to access programs
Catastrophic engine failure (complete seizure, metal in oil, bearing failure)
Multiple reports of complete engine failure with metal debris in oil pan, piston damage, or bearing failure. Symptoms appear suddenly or with minimal warning. Engines require full replacement ($11,000–$12,000+ cost). Some vehicles still within or near original warranty period.
When: At various mileages: 15,500; 31,000; 45,000; 80,000; 105,000+ miles; as early as 3 years of age
Symptoms owners cite: Loud knocking or ticking noise from engine; Smoke from exhaust on cold start; Sudden loss of power/stalling; Inability to crank or start; Rough running; Engine seizing
Codes mentioned: Random misfire codes (cylinders 3, 4, 5), Check engine light
Repairs/costs cited: Engine replacement required; parts found include metal shavings, failed valve keepers, dropped valves, piston fragments, fractured timing chain and spark plugs, intake valve fractures
Recalls/TSBs owners mention: NHTSA Campaign 24V635000 and 24V598000 issued but do not cover all affected VINs; some built within recall window (e.g., 9/21 build) still declined; extended warranty offered in some cases but repairs denied
Valve keeper failure (intake valve dropping into cylinder)
Intake valve keeper fails, allowing valve to drop into cylinder. Causes immediate engine damage, metal debris, and seizing. Known issue also reported in 2021 Bronco 3.0 EcoBoost (NHTSA investigation ongoing). Requires engine replacement, turbos, flywheel, and torque converter replacement.
When: At low mileage: 15,500 miles reported
Symptoms owners cite: Motor seized/unable to hand-crank; Metal pieces in oil pan
Repairs/costs cited: Engine, both turbos, flywheel, and torque converter replacement; customer offered to provide repair invoice
Recalls/TSBs owners mention: No warranty coverage; owner notes this is a known issue being investigated by NHTSA for 2021 Bronco 2.7 EcoBoost
Coolant intrusion into oil and engine failure
Coolant leaks into oil, contaminating bearings and damaging engine. Appears to relate to internal water pump leakage or gasket failure. Engine replacement required.
When: At approximately unknown mileage; notification received for NHTSA Campaign 24V635000
Symptoms owners cite: Check engine light; Burning odor; Sudden loss of power
Codes mentioned: Coolant intrusion diagnostic
Repairs/costs cited: Engine replacement recommended ($11,000 estimated); attributed to leaking water pump
Recalls/TSBs owners mention: NHTSA Campaign 24V635000 notification issued but VIN not included in recall
Fuel dilution of crankcase oil
Fuel leaks into crankcase oil, overfilling and contaminating oil. Owner reports 1.5 quarts of fuel in oil within 1000–1500 miles. Dealer confirmed issue and stated no repair available. Stated to eventually destroy engine from inside.
When: At 30,959 miles; started occurring in current year
Symptoms owners cite: Oil level overfull; Fuel odor in oil; Oil dilution
Repairs/costs cited: Dealer verified but stated no repair available; technician indicated eventual engine destruction likely
Recalls/TSBs owners mention: Dealer acknowledged issue; no fix currently available
Turbo failure (blown turbo)
Turbo fails suddenly, causing loss of engine power and smoke from exhaust. No warning light or diagnostic codes to alert owner before failure.
When: At unspecified mileage
Symptoms owners cite: Grayish smoke from both tailpipes; Sudden loss of acceleration; No warning lights or noise prior
Repairs/costs cited: Diagnosis: blown turbo
Timing chain, spark plug, and intake valve fracture
Timing chain, spark plugs, and intake valves all fracture together, causing loss of power and rough running. Requires full engine replacement.
When: At approximately 80,000 miles
Symptoms owners cite: Loss of acceleration and motive power; Ticking sounds from engine; Vehicle running rough; No warning light
Repairs/costs cited: Engine replacement required; fractured timing chain, spark plugs, and intake valves found
Recalls/TSBs owners mention: Manufacturer made aware; case filed
Exhaust flex pipe failure
Exhaust flex pipes fail and separate from exhaust system. Dealer confirmed as known failure.
When: At approximately 60,000 miles
Symptoms owners cite: Abnormally loud sound at idle
Repairs/costs cited: Both exhaust flex pipes required replacement
Recalls/TSBs owners mention: Dealer confirmed known failure; manufacturer notified and referred owner to NHTSA Hotline
Loss of compression (cylinders 3 and 4)
Cylinders lose compression, causing loss of power and stalling. Requires engine replacement.
When: At approximately 105,000 miles
Symptoms owners cite: Abnormal shaking and vibrating from engine compartment; Loss of automotive power
Codes mentioned: Cylinder compression codes
Repairs/costs cited: Engine replacement required
Recalls/TSBs owners mention: Manufacturer and dealer notified; no assistance offered; VIN not included in NHTSA Campaign 24V598000
Misfire and catalytic converter failure (related)
Vehicle experiences misfires from multiple cylinders triggered by or associated with catalytic converter issues. Dealers initially misdiagnosed, focusing on spark plugs and ignition instead of converter damage. Later found cylinder 5 had no compression. Relates to NHTSA Campaign 24S55 (valve failure causing engine failure).
When: Built in Chicago, 9/21 (within recall window 7/21–10/21)
Symptoms owners cite: Vehicle running rough; Stalling; Multiple cylinder misfires
Codes mentioned: P0430 or similar catalytic converter code, Misfire codes from multiple cylinders
Repairs/costs cited: Spark plugs and wires replaced initially (ineffective); later cylinder 5 found to have zero compression
Recalls/TSBs owners mention: Ford extended warranty on catalytic converters due to common problem; NHTSA Recall 24S55 issued for valve failure / engine failure but owner's vehicle VIN was built within campaign window but not initially included
Smoking on cold start and post-replacement
Engine produces heavy smoke on cold start even after engine replacement. No warning lamps, codes, or diagnostics thrown. Issue persists despite new engine installation.
When: Started at around 9,000 miles; continued after engine replacement
Symptoms owners cite: Smoke from engine on cold start; No warning codes or diagnostics
Repairs/costs cited: Engine was replaced at dealer but smoking persists; no root cause identified
Engine knocking and clattering before warning lights
Engine knocks and clatters before any warning lights illuminate. Owner suspects low oil or premature bearing failure common to 3.0 EcoBoost. Resulted in catastrophic engine failure.
When: 4-year-old vehicle (no specific mileage given)
Symptoms owners cite: Knocking and clattering noises; No warning lights initially; Catastrophic failure follows
Repairs/costs cited: Catastrophic engine failure occurred
Synthesized from 31 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.