I have been trying to figure out the cause for this sound for a few months now. Hoping it's not the Timing chain tensioners. My dad, that is a mechanic, says that it may be a lifter. I think it may be a coil pack. I saw a video of a GM motor with a VERY similar ticking/tapping sound, and it was a plug wire that was not on the coil. I know that it's a little different for the XK8, where it is a coil pack. If it is a coil pack issue, I cant take it off without a bolt extractor, that I haven't purchased yet. A previous owner/mechanic rounded out the bolts on most of the coil pack bolts, so I'm going to need a full set of new bolts. I found these when I tried to change my own sparkplugs. Couldn't even do that lol.

 

I would actually be starting at the serpentine belt and tensioners. Certainly doesn't sound like a big deal.

 

I had similar came and went ...no so prevalent in winter ..0 deg C so changed oil for 10w40 and it went though it does sound more like a lifter than piston slap.
try a mechanics stethoscope. turn the radio up.

 

Mine makes the exact same noise. After sleuthing I found it seems to be coming from cylinder 8. It sounds for all the world like a lifter tick. We thought perhaps it was an exhaust manifold leak so I disassembled the exhaust and did a smoke test up the left cat. Nothing. More research. This engine uses the infernal micro-shims for valve lifter adjustment. The genius mechanic who was employed by the previous owner replaced the heads and I strongly suspect he didn't quite get the shim stack correct on that one cylinder. Don't know if it's exhaust or intake.

More research. Jag has a tool, hard to find, about $300US, that will depress a valve so that you can remove and replace shims. Then you use a long feeler gauge to check. It's that or pull off the camshaft and re-rime the engine, I suppose.

I tried 5W-40 oil, and some Liqui-Moly Viscoplus. Didn't help a bit.

So, I guess I'll just live with it. Engine performance doesn't see to be affected at all.

 

Just to add that removing the cam cover is not too difficult (although cylinder 8 on bank 2, left-hand side, is slightly trickier than bank 1 and a 1/4 inch socket set with a U/J adapter is useful) so you could check the clearances.

If you decide to re-shim, it's not difficult to unbolt the camshaft and move it to one side to access the buckets. Just put a couple of cable ties around the chain and sprocket and lock then together to ensure that you cannot lose the valve timing.

Richard

 

Are you sure it's not the variable valve timing - mine makes that noise. Can you 'feel' the noise as a tapping when you put your hand on the cam cover?

 

you want 10w40 or 15 w 40 to kill it not 5 w 40

 

That's one of the primary timing chain stretched and hitting one of the guide its not harmful because these chains rarely break if you will do the tensioners replace the chain that's stretched I believe tsubaki makes them or iwis
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Thanks. I'll switch to one of those on the next oil change.

 

Replace the timing chains and tensioners. This should quell any "hazardous" noise. I would also replace the coil packs. This will narrow down any noses to the other source(s). If you still hear the noise, take it to a qualified mechanic for an appropriate diagnosis.

 

There is so much that can be done to track down the source of the noise and rule out any serious issues without spending a single penny.

Start cheap before you go expensive. 👍

Richard

 

I would disagree. There is no quicker way to fall out of love with a car than by emptying your wallet by firing the parts cannon at it. That's not a viable alternative to diagnosing and repairing.

 

I got smart and changed the guides/tensioners/chains right off the bat. I also had the plugs replaced, along with a plastic intake pipe and MAF sensor. this made all the difference in the world. A qualified Jaguar mechanic is worth his/her weight in gold.

 

Definitely sounds like a fuel injector tick. Normal noise.

 

Just bought a 2001 XKR the other day that sounds exactly like this! Has been sitting several years so my first move is to change the oil (which is dirty) with Castrol 5-40w or 10-40w. I also plan on putting in new ignition coils and spark plugs. At the moment it still sounds like a diesel truck

 

Was it sat with fuel in the tank? If so, have you drained and replaced it?

 

It has sat with the fuel tank, and now that I think about it, a 3/4 tank of fuel…