Lot C563: 2002 Jaguar XK8

The 2002 Jaguar XK8‘s 4.2L AJ27 V8 engine has a well-documented timing chain tensioner issue that you should definitely be aware of—especially given this car’s low mileage and age.

The Core Problem

The AJ-V8 engines used plastic-bodied timing chain tensioners in early production. These plastic tensioners become brittle over time, develop cracks, and can fail, leading to:

• Loss of chain tension
• That characteristic “rattling” or “diesel-like” noise on startup
• Potential jumped timing and catastrophic engine damage if left unaddressed

Primary vs. Secondary Tensioners

Your XK8 has two types of tensioners:

Primary (Lower) Tensioners – These tension the chains running from the crankshaft up. The good news: Jaguar switched to metal/aluminum-bodied tensioners starting August 13, 2001. Since this is a 2002 model, your primary tensioners likely have this upgrade—but verification never hurts.

Secondary (Upper) Tensioners – These tension the smaller chains at the camshaft level. Even on the 2002 4.2L, these remained more vulnerable. The secondary chains are still single-row (unlike the upgraded multi-row primary chains), and their tensioners are the ones most commonly questioned in your listing’s FAQs.

The Miles vs. Age Factor

With only 21K miles, you might think “low use = low risk.” Sadly, this is a time and heat issue, not just mileage. The plastic degrades simply sitting there. Many owners report failures between 35K–60K miles, but age is equally unforgiving.

What to Do

If you have service records showing tensioner replacement, that’s golden. If not, a pre-purchase inspection by a Jaguar specialist should include:

• Listening for tensioner rattle on cold start
• Checking service history for the “timing kit” service
• Possibly a borescope inspection through the timing cover

Replacement before failure is roughly $800–1,500—expensive, but a bargain compared to an engine rebuild.

Would you like me to check if there are similar XK8s in our listings that have documented tensioner service, or help you find a Jaguar specialist in your area?