Jaguar XJ X308Saloon1997–2003Every engine fitted to the X308-generation Jaguar XJ - from the 3.2-litre V8 to the 4.0-litre and the supercharged XJR. Real UK costs, honest reliability data, and the timing-chain question that defines ownership of Jaguar's first V8-powered saloon. Backed by real UK XJ enquiries in 2025 [JAG-VERIFIED].
X308Enquiries (2025)JAG-VERIFIEDSaloon
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Every engine fitted to the X308-generation XJ specifically - Jaguar's first V8-powered saloon, offered exclusively with the AJ-V8 engine family from 1997 to 2003.
Overview
The Jaguar XJ X308 is a full-size luxury saloon manufactured by Jaguar Cars from July 1997 to December 2002.
It was the third and final evolution of the XJ40 platform that had been in production since 1986, and the first XJ-generation to be powered exclusively by Jaguar's new AJ-V8 engine. Offered in 3.2-litre and 4.0-litre naturally aspirated forms, plus a supercharged 4.0-litre in the XJR and Daimler Super V8, the X308 kept the rounded four-headlamp bonnet, low roofline, sloping tail, and wrap-around rear light clusters of its X300 predecessor. It was succeeded by the all-aluminium X350 in 2003.
Key Facts
Platform
XJ40 (third and final evolution)
Predecessor
Jaguar XJ (X300)
Successor
Jaguar XJ (X350)
Sibling body styles
None - X308 is sole XJ body style; available in SWB and LWB
Market Intelligence
The X308-generation XJ is now a modern classic; enquiries are concentrated on timing-chain replacement and ZF 5HP24 transmission service, with values ranging from £4,000 for entry-level examples to £15,000+ for low-mileage XJRs.
Highest Risk
3.2 V8 (AJ26/AJ27)
“The 3.2 V8 is underpowered for the XJ's 1,800 kg kerb weight and carries the same timing chain tensioner and Nikasil risks as its larger sibling - but with less performance to justify the ownership anxiety.”
Who it's for: buyers on a tight budget who absolutely must have an X308 - but the 4.0 is a better choice every time.
Most Expensive Failure
4.0 V8 Supercharged (XJR)
“A reconditioned supercharged XJR engine costs £5,000–£9,000 supply-only, plus the supercharger itself adds maintenance complexity. Timing chain failure on these engines can be catastrophic if ignored.”
Who it's for: enthusiasts with deep pockets who understand the ongoing maintenance costs.
Best Value
4.0 V8 (290 bhp) - post-June 2000
“The 4.0-litre naturally aspirated V8 with steel cylinder liners and documented timing-chain work is the sweet spot in the range - best parts availability, simplest architecture, and the engine that defines the X308 character.”
Who it's for: the majority of X308 buyers - smooth, effortless V8 performance without the supercharger complexity.
Highest Risk
3.2 V8 (AJ26/AJ27)
“The 3.2 V8 is underpowered for the XJ's 1,800 kg kerb weight and carries the same timing chain tensioner and Nikasil risks as its larger sibling - but with less performance to justify the ownership anxiety.”
Who it's for: buyers on a tight budget who absolutely must have an X308 - but the 4.0 is a better choice every time.
Most Expensive Failure
4.0 V8 Supercharged (XJR)
“A reconditioned supercharged XJR engine costs £5,000–£9,000 supply-only, plus the supercharger itself adds maintenance complexity. Timing chain failure on these engines can be catastrophic if ignored.”
Who it's for: enthusiasts with deep pockets who understand the ongoing maintenance costs.
Best Value
4.0 V8 (290 bhp) - post-June 2000
“The 4.0-litre naturally aspirated V8 with steel cylinder liners and documented timing-chain work is the sweet spot in the range - best parts availability, simplest architecture, and the engine that defines the X308 character.”
Who it's for: the majority of X308 buyers - smooth, effortless V8 performance without the supercharger complexity.
Most Overlooked
4.0 V8 Naturally Aspirated (290 bhp)
“The standard 4.0 V8 is often overshadowed by the XJR, but it delivers the same refinement and character with significantly lower running costs. A well-maintained 4.0 XJ8 with steel liners and updated tensioners is one of the best-value classic Jaguars on the market.”
Who it's for: buyers who want classic V8 character without the supercharger's running costs.
The X308 rule
A £4,500–£8,000 4.0 V8 recon against a £4,000–£6,000 early X308 sits at 75–200% of the car's value - on a sub-£6,000 example, that brushes our 60% Jaguar threshold, and we'll honestly tell you to walk away. Against a well-kept £10,000+ example, the same recon drops to a routine 45–80% - a repair decision, not a financial one. Value the car first.
Key Takeaways
Which X308 Costs Least To Own?
4.0 V8 naturally aspirated - best parts availability, simplest architecture.
Which X308 Costs Most To Own?
XJR supercharged V8 - supercharger service and timing-chain work add cost.
Which X308 Is Best Value?
4.0 V8 XJ8 - the most common, best-supported, and most characterful engine in the range.
AJ-V8
Timing Chain Tensioner Failure
Affected models:
X308 3.2 V8, 4.0 V8, and XJR (all variants), particularly higher-mileage units.
Typical failure mileage:
80,000–120,000 miles.
Root cause:
The plastic timing chain tensioners degrade over time, leading to chain rattle, potential chain skip, and in catastrophic cases, valve damage. Secondary timing chain slip is a known failure mode that upsets emissions and can bend valves. Upgraded metal tensioners are available.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,500–£3,000
£1,000–£2,500
Chain, tensioners, guides replacement
Catastrophic (Replacement)
Dealer
Specialist
£6,000–£9,000
£4,500–£8,000
Full reconditioned engine
Our Recommendation
On any X308 approaching 80,000 miles with no documented timing-chain work, have the tensioners inspected immediately - £1,000–£2,500 preventative repair is dramatically cheaper than the £4,500–£8,000 replacement that follows if ignored.
ZF
5HP24 Transmission Issues
Affected models:
X308 3.2 V8 and 4.0 V8 (all naturally aspirated models).
Typical failure mileage:
80,000–120,000 miles.
Root cause:
The ZF 5HP24 transmission has well-documented issues including pressure control valve problems and cracked A-drums. Common symptoms include harsh downshifts, torque converter lockup issues, and transmission fault warnings. The TransGo repair kit can address pressure regulator issues.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,500–£2,500
£800–£1,800
Valve body repair, TransGo kit, fluid service
Catastrophic (Replacement)
Dealer
Specialist
£3,500–£5,000
£2,500–£4,000
Full reconditioned transmission
Our Recommendation
On any X308, service the ZF 5HP24 transmission every 60,000 miles - an £800–£1,800 preventative service is cheaper than the £2,500–£4,000 replacement that follows if ignored.
Nikasil
Bore Lining Degradation (Pre-2000 Engines)
Affected models:
X308 3.2 V8 and 4.0 V8 manufactured before June 2000.
Typical failure mileage:
60,000–100,000 miles.
Root cause:
Early AJ-V8 engines used Nikasil (nickel-silicon carbide) bore linings which are intolerant to high-sulphur fuel, leading to bore wear, oil consumption, and compression loss. Jaguar switched to steel liners from mid-2000 onwards.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
N/A - no preventative fix
N/A - no preventative fix
-
Catastrophic (Replacement)
Dealer
Specialist
£6,000–£9,000
£4,500–£8,000
Full reconditioned engine with steel liners
Our Recommendation
When buying an X308, prioritise post-June 2000 models with steel liners. If you own a pre-2000 example, monitor oil consumption closely and have a compression test performed at the first sign of excessive consumption.
Petrol Variants
Scope note: All variants listed are X308 XJ only. The X308 was the first XJ generation to be offered exclusively with V8 engines. The Daimler Super V8 was the top-of-the-range model, featuring the supercharged 4.0-litre V8 with enhanced luxury trim. In the United States, the 3.2-litre engine was not offered - all cars received the 4.0-litre V8.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
Most Common Failures
Petrol Variants
Scope note: All variants listed are X308 XJ only. The X308 was the first XJ generation to be offered exclusively with V8 engines. The Daimler Super V8 was the top-of-the-range model, featuring the supercharged 4.0-litre V8 with enhanced luxury trim. In the United States, the 3.2-litre engine was not offered - all cars received the 4.0-litre V8.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
Most Common Failures
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