Jaguar XJ (X351) 5.0 V8: Problems, Reliability & Repair Costs
"The X351 XJ was Jaguar's aluminum flagship. Depreciation makes them look like bargains. The air suspension and timing chain tensioner repair costs explain why."
Engine
5/10
Gearbox
5/10
Electric
4/10
Total Risk
6/10
Quick Verdict
Buy with CautionExpect significant running costs. Manageable if preventative maintenance is done.
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.
Executive Intelligence Summary
Is the Jaguar XJ / XJL (X351) reliable? Common problems with the 5.0L Supercharged V8. Air suspension sagging, sunroof creaking, and coolant leaks.
In This Guide
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 reliable 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:
- Weekly coolant checks.
- Premium 5k mile oil changes.
- Tolerance for a creaky sunroof.
In exchange, you get a car that feels like an event every time you drive it.
Keep Reading
- Ferrari 458 Italia vs Porsche 911 Turbo: Drama vs Precision
- Ferrari 458 Italia vs BMW M8: The Icon vs The Beast
- Porsche 911 Turbo vs BMW M5: The Surgeon vs The Sledgehammer
Executive 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.
