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Jaguar XJ (X351) 5.0 V8 Problems: The Flagship Bargain Guide

Sun Feb 15 2026
Reliability Score: 52 /100

Common Failure Points & Costs

Component Failure Mileage Symptom Est. Cost (USD) Risk Level
Water Pump 30k - 50k miles Coolant leak, overheating, pulley wobble $600 - $1,100 High
Sunroof Mechanism Any Loud popping/creaking over bumps, stuck glass $500 - $2,500 Low
Air Suspension (Rear) 60k - 90k miles Rear dropping overnight $1,000 - $1,800 Medium
Coolant Y-Pipe 60k - 80k miles Sudden coolant dump in valley $1,500 - $2,500 Critical
Timing Chain (2011-2014) 60k - 100k miles Start-up rattle $4,000 - $6,000 Critical

Reliability Verdict

The X351 XJ is an unbelievable value proposition, offering Bentley-lite luxury for Camry money. However, the 5.0L V8 carries the standard AJ133 risks (timing/cooling), and the aluminum chassis has unique body issues like sunroof rattles. It is generally more reliable than a BMW 7-Series of the same era, but maintenance is strictly required.

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Jaguar XJ (X351) V8 Reliability: The $15,000 Super-Limo

The Jaguar XJ (X351), sold from 2011 to 2019, looks like a spaceship and drives like a sports car. It was Ian Callum’s masterpiece. In “Supersport” or “XJR” trim, it packed the 510hp/550hp Supercharged V8 into an all-aluminum body that weighed less than a BMW 5-Series.

Today, you can pick one up for $15,000 - $25,000. Is it the deal of the century, or a financial suicide note?

1. Engine Reliability: The AJ133 Factor

The XJ uses the same 5.0L V8 as the Range Rover.

  • Timing Chains: 2011-2014 models are high risk. 2015+ are safer.
  • Coolant Pipes: All years are plastic and will fail.
  • Water Pumps: The XJ seems to chew through water pumps faster than other models. Keep an eye on the coolant level.

Advantage XJ: Because the XJ has a lower hood line and better airflow than a Range Rover, we see slightly fewer heat-soak related failures (like fried wiring harnesses), though the plastic pipes still die on schedule.

2. Body & Chassis Gremlins

The X351 was advanced tech. Aluminum monocoque, panoramic glass roof, digital dash.

The Sunroof Rattle

The panoramic roof on the XJ is notorious.

  • The Issue: The chassis flexes (it’s a long car). The mounting points for the sunroof creak, pop, and rattle.
  • The Fix: There are TSBs involving special grease, felt tape, and retorquing bolts. Sometimes it works. Sometimes it doesn’t.
  • Living with it: Many owners just accept the “pop” when entering a steep driveway.

Rear Air Suspension

Unlike the Range Rover (4-corner air), the XJ only uses air suspension on the rear axle (for load leveling).

  • Reliability: Better than Range Rover. Since it’s only the rear, the system is simpler.
  • Failure: The air springs leak around 80k miles.
  • Cost: Replacing two rear air springs is relatively cheap ($1,000) compared to a full 4-corner system.

3. Maintenance vs The Rivals

Compared to a BMW 750i (N63) or a Mercedes S550, the XJ is actually… reliable?

  • BMW 750i: Valve stem seals, oil consumption, turbo failures. (XJ has none of these).
  • Mercedes S550: Airmatic struts, expensive electronics.
  • The Verdict: The XJ V8 is arguably the most robust powertrain in the full-size flagship segment, provided the coolant pipes are done. The transmission is the bulletproof ZF 8HP (same as Audi/BMW). The electronics are simpler (and older) than the Germans, meaning fewer modules to fail.

4. XJR vs Supersport vs Portfolio

  • Portfolio (NA V8 or SC V6): Nice, but misses the point.
  • Supersport (2011-2013): 510hp. Usually fully loaded. High timing chain risk due to year.
  • XJR (2014-2017): 550hp. Stiffer suspension. The track-focused limo.
  • XJR575 (2018-2019): 575hp. The collector’s item.

Recommendation: Buy a 2016+ XJR. You get the best version of the engine, the updated infotainment, and a car that can legitimately embarrass sports cars.

5. Summary

The Jaguar XJ X351 is a maintenance-heavy car, but it doesn’t suffer from the engine-out nightmares of the BMW N63. It requires:

  1. Weekly coolant checks.
  2. Premium 5k mile oil changes.
  3. Tolerance for a creaky sunroof.

In exchange, you get a car that feels like an event every time you drive it.

Expert Buying Advice

The XJ Supersport or XJR (550hp) are the ones to hold value. Look for 2016+ models (updated LED headlights and infotainment) which also carry the safer engine timing guides. Avoid 2011 models.