Edit: Autocorrect in subject line "TOCK-ing, not ROCK-ing"

As of today my car's engine is making a regular sort of clacking or knocking noise. "tock, tock, tock, tock, tock", sort of thing. Sounds a bit diesel-y or tappet-y. I noticed it today while sat idling to run the heater etc. The engine was not cold, having driven for over an hour. Also, the oil gauge was precisely in the middle as it is.

I know the XK8 has a known issue with the plastic tensioners on the timing chain and that the warning sign that the tensioners are about to go is a "rattle" on cold start. Now, as I said, the car wasn't cold today (I'll reconfirm tomorrow morning) and the noise is more a tock-tock-tock than anything I'd describe as a rattle.

As I said it sounds a bit diesel-y (the shame!). Normally I'd say: "Ah! Needs oil!" And, true, it does burn a (very) little bit of oil. Now, it's dark, so I checked the dipstick and it seemed fine, but, again, I'll recheck in the daylight. If there's no rattle in the morning, I'll throw in some oil and see if it settles down.

The thing is, it was serviced recently, including an oil change (fully synthetic) and new sparks.

I don't have a full service history for it, so I don't know if the dreaded timing chain tensioners were replace, but I do know the following:

— Jaguar replaced them under warranty for any customer who asked
— The previous owner had multiple €5,000 services done on the car (I have the bills)

From these two facts I am 90pc sure the tensioners were replaced. What kind of lunatic has €5,000 services done on an old, but not valuable, car at the main dealer? A rich one. Such a person would surely have *all* work done, both necessary and unnecessary. The main dealer used this man as a walking cash machine.

Does it sound to you like it just needs a drop of oil? Should I switch from the specced fully synthetic to something a bit more viscous?

It could also be the VVTs, I suppose. Big end? (let's hope not!) Or a lot of things.

1997 Jaguar XK8 4.0L V8 X100 with naturally aspirated AJ26 engine. 93,000 miles on the clock.

 

Tensioner is my bet. They can make the noise you explain even when warm. Just means they are really moving around perhaps. I would suggest NOT driving it till you can verify.

 

Any easy methods to verify? Visit to the mechanic may have to wait for a while. In which case I'll not drive either, but not ideal.

 

It sounds closer to this than any of the videos of a tensioner I've watched and listened to:



In his case it was low on oil.

 

Call the dealer, ask for a service advisor and give him the P.O.'s name or vehicle VIN. Ask him to view the service records on his computer. Offer to prove you're the current owner if necessary. With a little luck he'll tell you.

 

You're a genius!

 

May the luck of the Irish be with you..

 

Ha! Thanks.

The optimist in me says, ah, burning a bit of oil. No big deal. My old Eunos did it all the time (180,000 on the clock, worn engine needed regular top-ups/changes). In fact, were it not for all the horror stories I've heard about the tensioners I'd not be too worried.

The middle option is water pump or sticky valve.

Timing chain or big end? I'm in trouble.

 

Checked the dipstick in the light of day. Low on oil. Have done 2,300 miles since last oil change. Added a litre of oil and the noise went away on next turnover.

I'm still going to see about the service history and, failing that, will at least get the tensioners and valve train looked at on next service. For now I can concentrate on all of the tiny but annoying electrical problems. None significant, but there are many.

 

My servive guy says this is piston slap, it goes away after a few min. when it warms up.
Jagnoise.mp4 Video by guzzisvt | Photobucket

This one was the primary and secondary timing chains. Didn't make noise until it was warmed up and didn't go away until $$$.
Jagnoise.mp4 Video by guzzisvt | Photobucket