I recently purchased a 2006 Super V8 with 140K miles and believe that the timing chains might be original from the service records provided with the car. Are they likely OK to leave alone or is there a recommended interval to change them ?
Thank you,
Mike

 

Believe the timing chain issue was resolved with the 04 XJ8's.

 

Yes, the timing chain issue was resolved with the introduction of the 4.2 litre version of the V8 in 2003.

They are considered as very reliable since then.

Bst regards,

Thomas

 

Like all moving parts, there will come a time when chains and tensioners will need replacing, but there is no fixed mileage or age for this, unlike timing belts. Here in Europe, some clever-dick engineers designed engines with the timing belt running in oil and many engines have gone bang over here due to this completetely stupid design. The belt wears, and the debris drops down into the sump, then blocks the input to the oil pump !

 

Not just Europe. Some American Fords I know of are wet-belt oil pump drives.

 

wfooshee posted;
Not just Europe. Some American Fords I know of are wet-belt oil pump drives.
That's the brilliance of the engineers at work here.
Planned to fail, obsolesce.

Subaru's water pump, is located inside the motor, another great idea.
Designed to leak coolant into the motor, diluting the oil.
Instead of onto the motor, allowing you smell the slight coolant leaks
Cash for clunkers, another plan to eliminate inexpensive, car's & parts.

 

I've seen posts from owners who've done >200K miles on their chains etc ... but those which failed may not have posted ... so ... replace if you hear worrying sounds or at some point inspect? (the guides, mainly?)

 

3.5 snd 4.2 V8 engines on x350/ x356 and x358 are like bullet proof. 2002 - 2009
230.000 miles on mine. From 2003
the 4.0 V8 of the x308 were problematic . Cylinder coating giving up leeding too.... chain tensioner leeding to...
2001 jaguar made some changes on those 4.0 l engines.

 

While I agree the 4.2L is by far the best in this area I think as posted above by Fraser Mitchell it's not a slam dunk because of time and wear. Any DOHC engine will sufferer from this over time. They have to because of the basic design. That DOHC setup puts huge and varying dynamic loads on the valve train and tensioners. And yes there have been 4.2L engines with this problem.
.
.
.

 

I have personally seen AJ33/AJ34 engines with failed secondary timing chain tensioners. As Fraser says above, they can fail, but it's best to remove the cam cover(s) and inspect the condition of the tensioners and chains.

The issue mentioned in one of the posts about failure of the Nikasil coating on the cylinder walls of the early AJ-V8s was due to poor fuel quality, not the engine design. The Nikasil issue was resolved in the early 2000s, so any engines still running with Nikasil are likely not prone to failure.