Ford Explorer 2006–2010Common problems, reliability & repair costs

Symptoms: Hard, lunging 1-2 and 2-3 shifts; RPM flare between 2nd and 3rd; delayed or banging reverse engagement; codes P0775, P0732/P0733/P0735. CarComplaints logs 308 transmission complaints on the 2006 alone, with problems starting as low as 40k–49k miles.

Fix: The root cause is usually worn servo pin bores in the case (fixed with oversized-sleeve servo bore kits) and/or a failed solenoid block. Caught early, a servo bore repair plus solenoid pack is the cheaper path; ignored, it becomes a full rebuild or replacement in the $2,500–$3,800 range. The V8's 6R60 6-speed does not share this problem.

Sources: CarComplaints — 2006 Explorer transmission, Transmission Repair Cost Guide — Ford Explorer 5R55, Ford Explorer Forums — 5R55S servo bore fix thread

Symptoms: Rattle or clatter on cold start that quiets after a few seconds — the plastic chain guides (cassettes) wear and the spring-loaded tensioners weaken, letting the chains whip. Left alone, the noise becomes constant, cassette debris ends up in the oil pan, and a jumped chain takes the engine with it.

Fix: External tensioner replacement (~every 75k miles per owner-forum consensus) is cheap insurance. Once cassettes are breaking up, the rear cassette sits at the back of the engine and requires pulling the engine — which is why quotes land in used-engine-swap territory. Address the noise early or buy the V8.

Sources: Ford Explorer Forums — timing chain cassettes in the 4.0L SOHC, Ford Explorer Forums — 4.0L tensioner replacement schedule

Symptoms: Coolant loss, crusty residue or seepage at the plastic end-tank seams, sweet smell, low-coolant or temperature warnings. CarComplaints logs 246 cooling-system complaints on the 2006, with radiator leaks averaging about $700 to fix at roughly 64,000 miles — and some owners report replacement radiators failing the same way.

Fix: Radiator replacement with fresh coolant. It's a bolt-in job on this truck; pick a quality unit rather than the cheapest aftermarket radiator, since repeat failures are part of the complaint record.

Sources: CarComplaints — 2006 Explorer cooling system

Symptoms: No driving symptom — this is a maintenance trap. The original Motorcraft two-piece plugs carbon-seize in the heads, and the lower shell snaps off below the threads during removal, leaving the tip stuck in the head.

Fix: Ford TSB 08-7-6 gives the official procedure: cold engine, back each plug out 1/8–1/4 turn, soak with carb cleaner for at least 15 minutes, then work them out slowly. Broken tips need a special extractor (or a shop that owns one). Replace with updated one-piece plugs so it never happens again. A car with documented plug replacement has already cleared this landmine.

Sources: Ford TSB 08-7-6 — spark plug removal procedure (PDF), Engine Builder — removing problem plugs on Ford modular engines

Symptoms: Humming or droning that rises with road speed and changes when you swerve gently side to side; sometimes ABS sensor codes from the affected corner.

Fix: Replace the hub/bearing assembly — the front units are bolt-on. Owner forums are consistent on one point: budget bearings fail again fast; use a quality brand (Timken/SKF/Motorcraft) and torque the axle nut to spec.

Sources: Ford Explorer Forums — chronic wheel hub/bearing issues (2008 4WD), CarComplaints — 2007 Explorer wheel bearing failure

Tools: Socket set + screwdrivers, Drain pan, Hose-clamp pliers, Fresh coolant (Motorcraft Gold spec)

1. Cold engine only: drain the coolant from the radiator petcock into a pan.
2. Disconnect the upper and lower radiator hoses and the transmission cooler lines (have a catch pan ready — they drip).
3. Unbolt the fan shroud and upper radiator supports, then lift the radiator out.
4. Drop in the new radiator, reconnect cooler lines, hoses, and shroud.
5. Refill with the correct coolant, bleed the air out at idle with the heater on hot, and check for leaks and proper transmission fluid level.

Tools: Floor jack + jack stands, Socket set + breaker bar, Large axle-nut socket, Torque wrench, Penetrating oil

1. Jack and support the truck, remove the wheel, and unbolt the brake caliper and rotor.
2. Unplug the ABS sensor connector and remove the axle nut (4WD).
3. Unbolt the three hub retaining bolts behind the knuckle — soak them with penetrant first.
4. Pull the old hub assembly, clean the knuckle bore, and seat the new unit.
5. Torque the hub bolts and axle nut to spec — over- or under-torquing the axle nut is the top cause of early repeat failure.
6. Reassemble brakes, plug in the ABS sensor, and test drive listening for the hum.

Tools: Spark plug socket + extensions, Torque wrench, Carburetor cleaner (for the soak), Broken-plug extractor kit (insurance)

1. Work on a stone-cold engine only — this is the single most important rule in Ford TSB 08-7-6.
2. Remove the coils, blow debris out of the plug wells, and back each plug out just 1/8 to 1/4 turn.
3. Fill each plug well with about 1/2–3/4 teaspoon of carb cleaner and let it soak at least 15 minutes.
4. Work each plug out slowly, backing up and re-soaking if you feel it start to bind.
5. Install updated one-piece plugs with a dab of nickel anti-seize, torqued to spec, and reinstall the coils.