I have developed a pretty distinct clacking noise from the engine in my 1999 XK8 with 98K miles.I suspect a valve adjustment and or timing chain replacement is due. This engine does have the nicosil coated cylinders and i wonder if they may be noisy as well. Before starting my teardown I am trying to find a chiltons or haynes repair manual in book form.
I cant seem to find these books on line, any thoughts appreciated.
Thanks again
MEM

 

My first thought is your tensioners could be breaking up and the timing chains are running slack. If I'm right, it's a short step from there to engine destruction.

If there was going to be an issue with the nikasil cylinder bores, it would most probably have appeared long before now as the fuel with sulphur content that caused the premature and excessive wear was withdrawn years ago.

Graham

 

Be sure to eliminate the clicking of the purge valve as a cause of the noise. It is located on the driver side wheel well. The clicking is head most at idle and when the weather is cold. It cycles on and off every minute or so. Just a thought.

 

There is no Haynes or Chilton's for our car. Your best bet is the forum itself - if you go to the XK8/XKR forum and look for the stickies. Find the DIY sticky (link also posted below) and scroll down to the Workshop Manual and download the Second Edition

https://www.jaguarforums.com/forum/x...ts-data-29800/

As someone who has just suffered a broken secondary timing chain - recommend investigating ASAP before driving any further

 

I would recommend the first step in investigating would be to remove the serpentine belt. Start the engine without the belt in place. If it still makes the noise it is engine related.
If the noise stops then start checking pulleys for bad bearings and check the tensioner for a weak spring. A bad belt tensioner will make a clicking noise as well as a bad pully bearing.

 

you should really be judicious about starting that engine again. at your mileage the tensioners need to be updated anyway unless you have proof that they were already replaced. start the job of replacing the upper and lowers and you will discover if this was the source of the problem. if the sound still remains, it will not be something serious.

 

Is it doing it all the time, or on acceleration, overrun or in a particular rpm band? need a bit more info thanks and what exactly is a clacking noise anyway?

 

There is an old toy that was a wooden U with a loose piece of wood between the U, when shaken it would make a "clacking" sound. That is about the best description I can imagine, Its not a tapping sound from loose tappets common in older cars. It is not too loud (cant hear from in car) and is loudest at idle, frequency increases and volume decreases with higher RPM. I believe it is the tensioners but appreciate any comments you all may have.
Thankyou
MEM

 

It certainly puts a big question mark over the tensioners. I wouldn't do any more testing or speculation before examining them.

Graham

 

It could be the VVTs making noise. BUT, if the secondary cam chain tensioners haven't been replaced they are overdue and a ticking time bomb.

 

Remove the cam covers and inspect the secondary timing chains and tensioners before attempting to start the engine again.

Report back what you find.

 

I have two videos on the attached link with noise that is related to the tensioners see if that is what you are hearing.

Link JagRepair.com - Jaguar Repair Information Resource

 

thanks to all, I will begin teardown this weekend.
MEM

 

Have you got an engine stethoscope? at least you can pin it down that way without unnecessary work. I though tensioner issues resulted in a rattling noise not a clack?
This is more like a clack

 

Sounds like my serpentine belt tensioner before the belt wrapped around the alternator pulley. Loudest at idle.