Engine knock when idling only

[mjd1]

My 1997 XJ8 4.0 V8 - 91,000 miles and new timing chains and tensioners at 67,000 miles - has a clicking noise at idling speed but stops when the engine speed is raised. The click also cannot be heard when driving. I use 5W 30 oil.

I've been told it could be a valve but this cannot be identified unless all valves are examined; it could be a valve lifter; timing chains; wrong oil; oil pressure. It has just been serviced and the engine was flushed but the noise is still there although it appears to be a little quieter.

It's not very clear whether this is a harmless and/or usual problem but I think it's necessary to investigate.
Any knowledge and advice on this please?

[andypryce]

Hi, others on here will undoubtedly be better able to advise, but if it is any reassurance I had similar on my XJ8 and the previous XJ40 (more so on the XJ8), and was told it was valve seats and not to worry about it, unless performance diminished or it started using oil. I just ignored it therefore and it remained the same. But I am no mechanical expert.....

[Brakebuster]

sounds like the VVT to me,

located at the front of each cam cover , they can make a ticking noise when getting old

use a slightly thinner oil to get to the upper galleries quicker when cold , or at tick over,

BB

you can also put an oil additive in , like molly-slip etc , will make the cat purrrrr again with little cost

[robv12]

yep, 4.0 "clack" sticky VVT, live with it!!

[J44EAG]

I have a VVT unit which ticks when the engine is cold.

Mike

[andypryce]

VVT

[andypryce]

Variable Valve Timing, of course!

[robv12]

DOH!!!

[andypryce]

Indeed, double doh !