The 2000 XK8 with the 4.0L AJ-V8 is a beautiful grand tourer plagued by catastrophic engine failure from Nikasil bore coating issues and chronic plastic component failures in the cooling and timing systems. Early AJ-V8s built before late 2000 are ticking time bombs.
Nikasil Cylinder Liner Failure (Pre-Late 2000 Engines)
Common · high severityTypical onset: 60,000-100,000 mi
Symptoms: Excessive oil consumption (quart per 500-1000 miles), Loss of compression on multiple cylinders, Blue smoke on startup and acceleration, Rough idle and misfires, Sulfur smell from exhaust due to high-sulfur fuel damaging Nikasil coating
Fix: Complete engine replacement or rebuild with steel-lined cylinders (Nikasil replacement). Requires 25-35 hours labor. Jaguar extended warranty covered some through 2010 but that's expired. Only real fix is swapping in a post-2000 steel-liner block or full rebuild with Linered sleeves.
Estimated cost: $8,000-15,000
Upper Timing Chain Tensioner and Guide Failure
Common · high severityTypical onset: 70,000-120,000 mi
Symptoms: Rattling noise from front of engine on cold start (first 3-5 seconds), Metallic chain slap sound that disappears when warm, Check engine light with cam/crank correlation codes, Catastrophic failure causes jumped timing and bent valves
Fix: Replace upper primary tensioners (plastic, known weak point), secondary tensioners, guides, and chains while you're in there. Requires front engine teardown including removal of both cam covers. 12-16 hours labor. DO NOT ignore the rattle—it will grenade.
Estimated cost: $2,500-4,000
Plastic Coolant Crossover Pipe and Thermostat Housing Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Coolant smell in cabin or under hood, Visible coolant weeping from valley between cylinder banks, Overheating or fluctuating temperature gauge, Low coolant warning light
Fix: Replace plastic crossover pipe in the valley and plastic thermostat housing with updated metal parts. Requires upper intake plenum removal. 6-9 hours labor. Smart owners do this preventatively along with all coolant hoses.
Estimated cost: $1,200-2,200
ZF 5HP24 Transmission Oil Cooler Line and Radiator Failure
Common · high severityTypical onset: 80,000-140,000 mi
Symptoms: Transmission fluid in coolant (strawberry milkshake in overflow tank), Harsh shifting or slipping after radiator failure, Pink residue on radiator cap, Complete transmission failure if cross-contamination not caught early
Fix: Internal transmission cooler fails inside radiator, mixing ATF and coolant. Requires radiator replacement, complete transmission fluid flush (often external cooler install recommended), and if contaminated badly, transmission rebuild. 4-6 hours for radiator/flush, add 18-24 for trans rebuild if damaged.
Estimated cost: $800-1,500 (catch early), $4,000-6,500 (trans damaged)
Secondary Air Injection System (Air Pump) Failure
Occasional · low severityTypical onset: 80,000-120,000 mi
Symptoms: Check engine light with P0410 or P0418 codes, Loud squealing from air pump on cold start, Failed emissions testing in states that check, No drivability impact, just emissions compliance
Fix: Air pump motor seizes or check valves fail. Can delete system if emissions testing not required in your area, or replace pump and valves. 2-3 hours labor for pump replacement.
Estimated cost: $600-1,200
Front Suspension Lower Control Arm Bushings
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking over bumps from front end, Wandering steering or vague feel, Uneven tire wear on inside edges, Visible cracking or separation of rubber bushings
Fix: Lower control arm bushings deteriorate. Some techs press in new bushings (if you can source them), but most replace entire control arms due to difficulty and availability. 4-6 hours for both sides with alignment.
Estimated cost: $1,000-1,800
Convertible Top Hydraulic Cylinder Leaks (Convertible Only)
Occasional · low severityTypical onset: null
Symptoms: Top operates slowly or stops mid-cycle, Visible hydraulic fluid on cylinders or trunk carpet, Top won't latch properly, Pump runs continuously
Fix: Hydraulic ram seals fail. Replace rams and flush/refill hydraulic system. 3-5 hours depending on which rams. DIY-friendly if you're patient, but heavy components.
Estimated cost: $800-1,500
Only buy if you verify it has a post-2000 steel-liner engine or documented Nikasil replacement, and budget serious money for timing chains and cooling system—otherwise you're financing an expensive driveway ornament.
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.