Free used car buyer guide / U251 fourth generation transition / 2005-2008
Ford Explorer common problems and best years
By BYBA Research - how we score cars
Updated 2026-06-12
BYBA Buy Score
6.4/10
1 walk-away risk, 5 serious faults, 2 minor faults documented for this generation, weighted by severity and repair cost. Biggest factor: 4.0 sohc timing-chain cassette rattle. Score methodology.
The 2005-2008 Explorer spans the last third-gen year and the 2006-on U251 redesign, so year matters. The expensive checks are 5R55 transmission servo-bore/shift failure, 4.0 SOHC timing-chain rattle, 4.6 3V spark plug/phaser risk, rear differential whine, radiator/cooling leaks, wheel bearings, rusted rear suspension/frame areas, liftgate cracks, and 4x4 transfer-case faults. Best buy is a rust-free 2007-2008 4.6 with quiet engine, clean transmission shifts, and no rear diff howl.
Faults covered
8
Highest risk
4.0 SOHC timing-chain
Best years
2007-2008
Best buys
- 2007-2008 4.6 V8 with clean plug/phaser history and smooth 6-speed.
- 2006-2008 4.0 only if no chain rattle and transmission is proven.
Inspect hard
- 2005 carefully because it is previous generation but still shares 4.0/5R55 risks.
- Any 4x4 for transfer case and front driveline noise.
Avoid
- 4.0 with cold start chain rattle from rear of engine.
- Any Explorer with hard 2-3/3-4 shifts, OD light flash, or rear diff howl.
Next checks
Before you contact the seller
Check the car's history first. Then bring the right tools if it still looks worth viewing.
Primary next step
Check history, title, and recall status
The faults above matter more if the car also has accident history, finance flags, missing service records, or open safety recalls.
Viewing kit
Bring the right tools
Four cheap tools catch most of the faults on this page at a Ford Explorer viewing.
Printable workflow
Take the inspection pack
The PDF is the ordered checklist for the viewing: documents, walk-around, test drive, and scan.
Open PDF optionSome links here are partner links. If you buy through one, BYBA earns a commission. The price you pay does not change. How we make money.
Engines and trims
Which Ford Explorer should you buy?
On most used cars, the engine and trim choice changes the risk more than the mileage does. Narrow this down before you start viewing cars.
4.0 SOHC Cologne V6
2005-2008
COMMON BUT CHAIN-SENSITIVE
Can last, but rear timing-chain cassette noise is a major labour problem.
4.6 Modular V8
2006-2008 main U251 V8
BETTER IF DOCUMENTED
Stronger and often paired well, but 3-valve plug/phaser issues still apply.
Ford Explorer market/trim variant 3
2005-2008
VERIFY EXACT SPEC
Catalogue coverage is market-sensitive, so confirm the engine, gearbox, drivetrain and recall population by VIN before applying the fault rows.
Year notes
Year-by-year buyer advice
Use this to narrow the search before you spend time travelling to view a car.
2005
Final older-generation Explorer year.
Buyer: Treat separately from 2006-on; transmission and rust still dominate.
Owner: Keep transmission service and rear diff records.
2006
U251 redesign with new frame/body and available 6-speed V8.
Buyer: Check early redesign electronics and driveline.
Owner: Address cooling leaks before overheating.
2007
Mature U251.
Buyer: Good target if engine/transmission are quiet.
Owner: Maintain diff/transfer fluids.
2008
Late U251 with same core risks.
Buyer: Best year in this set if rust-free.
Owner: Fix wheel bearing/diff noise early.
Common problems
Faults to check before buying
What fails, what it looks like, what it costs, and the quick checks you can do at the viewing - ranked by how badly each one can hurt you.
Fault 1
5R55 automatic servo-bore wear and hard shifts
Affects
2005-2008 V6 and some applications with 5R55.
Symptoms
Hard 2-3/3-4 shift, flare, OD light flashing, delayed reverse.
Typical repair cost
USD 600-1,500 servo-bore repair; USD 2,800-4,800 rebuild.
Codes / scan clues
P0732, P0733, P0775, P0795.
Root cause: Servo pin bore wear causes pressure loss and band apply faults.
Quick check
- Drive cold and hot through all gears.
- Watch for OD light flash after highway driving.
- Scan transmission codes and adaptation history.
- Check ATF condition and rebuild receipts.
Fault 2
4.0 SOHC timing-chain cassette rattle
Affects
2005-2008 4.0 V6.
Symptoms
Cold start rattle, rear engine chain noise, rough running, timing codes.
Typical repair cost
USD 1,800-4,000 chain/cassette work; USD 4,500+ engine-out repair.
Codes / scan clues
P0016/P0018-style timing correlation, misfire codes.
Root cause: Plastic timing-chain guides/cassettes wear; rear chain access is labour heavy.
Quick check
- Cold start after sitting overnight.
- Listen near rear of engine/firewall for chain slap.
- Scan for timing/misfire codes.
- Avoid "only rattles for a second" trucks without repair proof.
Fault 3
4.6 3V spark plug breakage and phaser noise
Affects
2006-2008 4.6 V8.
Symptoms
Misfire, broken plug extraction, hot idle tick/rattle, VCT codes.
Typical repair cost
USD 300-1,200 plugs; USD 1,800-4,000 phaser/timing repair.
Codes / scan clues
P0300-P0308, P0011/P0021.
Root cause: Two-piece plugs seize; VCT phasers depend on clean oil pressure.
Quick check
- Ask for plug replacement receipt using correct tool/procedure.
- Cold and hot idle for phaser rattle.
- Scan for misfire/VCT codes.
- Prefer documented V8 over neglected V6, not just any V8.
Fault 4
Rear differential whine and bearing wear
Affects
2005-2008 Explorer, especially higher-mile examples.
Symptoms
Whine on acceleration/deceleration, rumble, metal in diff oil.
Typical repair cost
USD 600-1,500 bearing setup; USD 1,800-3,500 differential replacement.
Codes / scan clues
None.
Root cause: Pinion/carrier bearing wear, gear wear, or low/old differential oil.
Quick check
- Drive 35-65 mph on and off throttle.
- Listen from rear for whine that changes with load.
- Inspect diff for leaks and service records.
- Check for mismatched tyres on 4x4/AWD.
Fault 5
Radiator, thermostat housing, and cooling-system leaks
Affects
2006-2008 U251, both engines.
Symptoms
Coolant smell, low coolant, overheating, cracked plastic housing, wet radiator seams.
Typical repair cost
USD 300-900 housing/radiator; USD 2,000+ if overheated engine damage.
Codes / scan clues
P0128, overheat and misfire codes.
Root cause: Ageing plastic cooling parts and radiator seams leak.
Quick check
- Pressure-test cooling system if possible.
- Inspect radiator side tanks and thermostat housing.
- Check for coolant smell after hot drive.
- Reject overheated engines with milkshake oil or misfires.
Fault 6
Wheel bearing/hub noise and ABS sensor faults
Affects
2005-2008 Explorer.
Symptoms
Growl with speed, ABS light, vibration, play at wheel.
Typical repair cost
USD 300-700 per hub.
Codes / scan clues
Wheel-speed sensor/ABS codes.
Root cause: Integrated hub bearing wear; sensor wiring can fail with hub.
Quick check
- Sweep left/right at 30-50 mph and listen for growl change.
- Check wheel play safely.
- Scan ABS module.
- Inspect tyres for cupping that can hide bearing noise.
Fault 7
Rusted rocker panels, rear suspension mounts, brake lines
Affects
Salt-belt 2005-2008 Explorers.
Symptoms
Soft rockers, flaky rear frame/suspension areas, brake line corrosion.
Typical repair cost
USD 500-2,000 brake/patch work; USD 3,000+ structural rust.
Codes / scan clues
None.
Root cause: Road salt trapped in body/frame and rear suspension areas.
Quick check
- Inspect rockers, rear subframe/frame rails, spring/control-arm mounts.
- Check brake lines over rear axle.
- Tap suspicious metal with pick/hammer.
- Avoid structural perforation even if it drives well.
Fault 8
Liftgate applique crack, water leaks, and rear electrical faults
Affects
2005-2008 Explorer.
Symptoms
Cracked rear panel, water in cargo area, rear wiper/lock faults.
Typical repair cost
USD 200-700 trim/seal repair; USD 800-1,500 wiring/module if water damaged.
Codes / scan clues
Body module/liftgate codes possible.
Root cause: Plastic liftgate applique cracking, seal failure, water intrusion into rear wiring.
Quick check
- Inspect liftgate panel around Ford badge and glass.
- Check spare-wheel well and cargo carpet for moisture.
- Test rear wiper, lock, glass release and defroster.
- Look for silicone/sealant repairs.
Inspection pack
Printable checklist for the viewing
The free page helps you decide whether the car is worth seeing. The paid guide is the ordered, printable checklist you use at the car.
- VIN recall check for Ford Explorer 2005-2008.
- Service invoices matching the engine/drivetrain and mileage, not only stamped history.
- Inspect tyres, leaks, accident repair and water entry before the test drive.
- Look specifically for evidence related to 5R55 automatic servo-bore wear and hard shifts.
- Check every warning light, infotainment function, climate mode, camera/sensor warning and battery condition before moving.
- Cold start, full warm-up, low-speed manoeuvres and motorway-speed pull for Ford Explorer.
- Recheck for smells, warning lights, harsh shifts, vibration or coolant/oil leaks after the drive.
- Scan engine, transmission, ABS/body and driver-assist modules where fitted.
- Treat cleared codes or incomplete readiness monitors as negotiation or walk-away evidence.
Bottom line
Buy: 2007-2008 4.6 V8 with clean plug/phaser history and smooth 6-speed. 2006-2008 4.0 only if no chain rattle and transmission is proven.
Avoid: 4.0 with cold start chain rattle from rear of engine. Any Explorer with hard 2-3/3-4 shifts, OD light flash, or rear diff howl.
Quick answers
Ford Explorer buyer questions
The short versions of what this page answers in full.
What are the most common Ford Explorer 2005-2008 problems?
The highest-impact documented faults are: 5R55 automatic servo-bore wear and hard shifts; 4.0 SOHC timing-chain cassette rattle; 4.6 3V spark plug breakage and phaser noise. This guide covers 8 faults in total, each with symptoms, typical repair costs, and checks you can do at a viewing.
Which Ford Explorer years are the best to buy?
2007-2008 stand out in this generation. 2007-2008 4.6 V8 with clean plug/phaser history and smooth 6-speed. 2006-2008 4.0 only if no chain rattle and transmission is proven.
Which Ford Explorer should I avoid?
4.0 with cold start chain rattle from rear of engine. Any Explorer with hard 2-3/3-4 shifts, OD light flash, or rear diff howl.
Is the Ford Explorer 2005-2008 a reliable used buy?
BYBA scores it 6.4/10 (buy with checks). 1 walk-away risk, 5 serious faults, 2 minor faults documented for this generation, weighted by severity and repair cost. Biggest factor: 4.0 sohc timing-chain cassette rattle.
Get updates when this guide changes
Recalls get added, repair costs shift, and new fault patterns show up in the data. Leave an email and we'll tell you when the Ford Explorer guide gets a meaningful revision. Nothing else, no selling your address.