Timing chains on 4.2 normally aspirated S-type

[PARKIE007]

I have a 2003 4.2 V8 normally aspirated S-type which has done around 130,000 miles. There are no nasty noises and the engine runs very smoothly but I have heard that there is a need to replace the timing chains and/or tensioners at certain intervals. Does this just apply to the earlier 4.0 model or is it something I need to have done and if so, what are the recommended mileages?

[davidr]

The advice to upgrade the timing chain tensioners only applies to the 4.0 engines. The original ones are weak and can (probably will!) fall apart. The recommendation is to upgrade to the latest tensioners fitted to the 4.2 like yours which are much more robust.
In short, you don't need to worry!

[J44EAG]

I totally agree with David.

Third generation metal tensioners and up-rated timing gear were fitted to all V8 4.2 motors at the factory as an original fit. To my knowledge, we have only ever seen and heard about just one instance of timing gear issues since the upgrade was done back around 2003. To all intents, the 4.2 fitted in XK8, XJR, XFR and S-type is almost totally bulletproof and does not need any investigation or remedial work applied. Its a much tougher engine than the earlier 4 litre unit. Relax and enjoy.

Mike K

[PARKIE007]

Many thanks to both of you for taking the trouble to respond so quickly - and with the best answer too! All the best, Chris.