The 2001 XK8 with the 4.0L AJ-V8 is a beautiful GT car plagued by catastrophic Nikasil cylinder liner failures and complex secondary chain tensioner issues that can grenade the engine without warning. When healthy, it's a pleasure; getting there or keeping it there requires deep pockets and preventive vigilance.
Nikasil Cylinder Liner Failure (Early AJ-V8 Engines)
Common · high severityTypical onset: 60,000-100,000 mi
Symptoms: Excessive oil consumption (1 qt per 1,000 mi or worse), Loss of compression in multiple cylinders, Blue smoke on startup and under load, Rough idle and misfires, Catastrophic bearing failure if driven low on oil
Fix: Complete engine rebuild or replacement. Nikasil liners react badly to high-sulfur fuel, causing bore scoring. Rebuild with steel liners requires 40-60 labor hours including R&R, machine work, and reassembly. Many opt for used replacement motors.
Estimated cost: $8,000-15,000
Secondary Chain Tensioner Failure
Common · high severityTypical onset: 80,000-120,000 mi
Symptoms: Rattling noise from rear of engine on cold start (first 5-10 seconds), Timing chain noise that disappears once oil pressure builds, Check engine light with cam/crank correlation codes, Sudden catastrophic failure: bent valves, destroyed guides, possible piston contact
Fix: Replace all secondary chain tensioners, guides, and chains (primary while you're in there). Engine must come out or be significantly disassembled. Updated metal-body tensioners are the fix. 35-50 hours labor depending on approach.
Estimated cost: $6,000-10,000
Plastic Coolant Crossover Pipe Failure
Common · high severityTypical onset: 70,000-110,000 mi
Symptoms: Coolant weeping or spraying from valley between cylinder banks, Rapid overheating, Coolant smell in cabin or steam from engine bay, Puddle of coolant under car after sitting
Fix: Replace plastic crossover pipe with updated metal version. Requires intake manifold removal to access. Also replace thermostat and hoses while accessible. 8-12 hours labor.
Estimated cost: $1,800-2,800
Transmission Oil Cooler Leaks and Failure
Common · medium severityTypical onset: 90,000-130,000 mi
Symptoms: Transmission fluid leaking from front of engine area, Milky or contaminated transmission fluid (cooler failure mixing with coolant), Transmission slipping or delayed engagement if fluid contaminated, Pink residue in coolant reservoir
Fix: Replace transmission oil cooler and flush both cooling and transmission systems if cross-contamination occurred. If coolant entered trans, may need full transmission rebuild. Cooler replacement alone: 4-6 hours.
Estimated cost: $800-1,500 (cooler only), $3,500-5,500 (if trans rebuild needed)
ZF 5HP24 Transmission Valve Body and Solenoid Issues
Occasional · medium severityTypical onset: 100,000-140,000 mi
Symptoms: Harsh or delayed shifts, especially 2-3 or 3-4, Transmission slipping in certain gears, Limp mode (stuck in one gear), Fault codes for shift solenoids or pressure control
Fix: Remove transmission, disassemble, replace valve body and/or individual solenoids. Often combined with full service (filter, fluid, seals). 12-16 hours labor for valve body replacement.
Estimated cost: $2,200-3,800
Suspension Component Wear (Lower Control Arm Bushings, Ball Joints)
Common · low severityTypical onset: 80,000-120,000 mi
Symptoms: Clunking over bumps from front suspension, Wandering or vague steering feel, Uneven tire wear on inside edges, Failed inspection due to ball joint or bushing play
Fix: Replace lower control arms with bushings, upper/lower ball joints as needed. Jaguar parts are expensive; aftermarket available. Alignment mandatory after. 6-10 hours for full front refresh.
Estimated cost: $1,500-2,800
Electrical Gremlins (Window Regulators, Seat Modules, HVAC Blower)
Occasional · low severitySymptoms: Power windows slow or falling into door, Seat memory or adjustment functions intermittent, HVAC blower motor dead or stuck on one speed, Instrument cluster pixels fading or backlight out
Fix: Window regulators are plastic-gear nightmares; replace with metal-gear aftermarket units (2-3 hrs per door). Seat modules often need removal and refurbishment or replacement (3-4 hrs). Blower motor is behind dash (4-6 hrs). Diagnose first—labor adds up fast on electrical issues.
Estimated cost: $400-1,200 per issue
Only buy if you have a $10k emergency fund, detailed service records proving engine work is done, and a trusted Jaguar specialist on speed dial—otherwise, admire from afar.
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.