John:
So you are saying it is the primary chain tensioners?

I meant just the plastic cover on top of the plenum, not the valve cover.

I am a little surprised that the tensioners would go out that early.
I am well aware of how much work goes into changing the timing chain out. You have to pull off most of the front of the engine and a half of the top.

I have a 89k miles XKR. But the engine was replaced 20k miles ago.

HOLY CRAP! What happened?? Don't keep us in suspense.

there was a faulty indicate light about engine oil, and the engine was blown. The dealer got me a new engine (under warranty).

I just purchased 2011 Range Rover Supercharged, same motor as Jaguar.
Cold start you will here rattle sounds like lifter noise, it will go away, that's what mine sounds like at 67000 miles. I have talked with the dealer and no help on warranty. Labor 9.7 hrs. on RR. I wonder how many have this problem? Also supercharger rattle. Serious problems for high line manufacture.

Sounds like the torsion isolator may be on the way out? Does it sound like a can of marbles near the snout?

2010 XFR, 90k miles. Had significant diff work (replaced the diff?) around 80k, replaced under the CPO warranty (on a business trip right now so car and paperwork are not with me). Indications were that I would get a "rubbing" noise from under the car during tight turns at lower speed, such as making a u-turn at a traffic light. Then started getting E Diff fault codes at lower temperatures.

I'm still not sure that the diff is quite right though. Drove the car briefly during icy conditions, with the right rear wheel on ice and the left rear wheel on dry pavement, the right wheel would spin and slip. A properly functioning diff would transfer the torque to the left wheel to move the car. Took it to the dealer, but the dealer said it checks fine...

Cheers, Will

Did I miss the photos? Still interested...

Your dsc should reduce or eliminate that wheelspin. The electronically controlled LSD will permit some wheelspin, which is one reason they can overheat. Conventional clutch pack type LSD pretty much lockup quite quickly. Torsen never lock up but I'm pretty sure the electronic diff uses clutch packs with an electronically modulated oil pressure control on clutch pack pressure.

Actually a Torsen diff DOES lock up. VERY WELL! Had one on my 1999 Z28
See the 4:00 mark, The Limited slip diff (Essentially what our XFR has) explained is the next vid.

No it doesn't , sadly.

If one wheel is off the ground it just spins and no torque goes to the stationary wheel

So what's the point of the diff then?

If I understand what you're saying, my diff is working as Jaguar designed it. That is, from a standing stop one wheel on a slick surface (e.g ice) will just spin and no torque transferred to the other wheel...

Cheers, Will

Um, I believe that everything has an "open" differential and that the traction control, along with ABS, is used to control wheel spin. That spinning wheel should have the brakes applied to it and that should transfer torque to the other side.

Doesn't it?
================================================== ===========
Understeer is when you hit the wall with the front of the car
Oversteer is when you hit the wall with the rear of the car
Horsepower is how fast you hit the wall, and
Torque is how far you take the wall with you

I'm not sure which diff we're talking about. The electronic diff in the XFR is a "smart LSD". It acts like an open diff unless the computer controlling it decides to apply some pressure to the clutch packs. In a passive clutch pack type this pressure is provided by a wedge in a diamond shaped slot so is not controllable. Depending on the programming it is entirely possible for an electronic diff to spin a wheel but I suspect the software doesn't normally allow complete wheelspin.

A Torsen diff is torque biasing rather than limited slip. As long as both wheels have some grip it behaves much as a passive clutch pack diff with one important difference. Since it biases torque away from the wheel with less grip and transfers it to the wheel with more grip it is more efficient. However, since it only biases torque it can only transfer torque up to the bias ratio. An open diff has a 2:1 bias ratio and Torsen are built in various ratios up to around 6:1 in some applications. If one wheel has no grip a Torsen has nothing to push against so cannot bias torque send you get wheelspin as for an open diff.

A fully electronic traction control makes any form of LSD or Torsen a bit pointless since the electronics simply brake the slipping wheel. This allows more torque to be applied to the open diff since any excess torque over tire grip at one wheel will be absorbed by the brakes on that wheel.

Combine electronic traction control with a Torsen and you get very good results although handling can be exciting as the diff biases torque resulting from brake resistance rather than tire grip. Try a modern mustang GT which are equipped with a pretty tight Torsen, for an illustration of the sphincter tightening effects of a torsen with traction control.

Sort of. The brake absorbs torque normally lost to wheelspin allowing more engine torque to get to the wheel with grip. A passive clutch pack LSD operates in the same way until both tires lose grip. This is one reason clutch pack LSD are no longer fitted by road car makers. The Torsen or helical diff works just fine especially with electronic traction control.

Just had an XFR with 170k traded in. Still running strong and no leaks.Guy treated it like a rally car too. Only issues these motors have is the water pump, supercharger vibration isolator, and timing chain tensioners. There are updated parts for above, and you'll have more than enough of a heads up before something fails.

Early production 5.0's had a timing chain tensioner that could collapse. There is an updated part. Pretty involved job. Not very common, done maybe 4 in the last year. Sucks, they used to pay 15hrs .

Not entirely relevant, but I just bought a 4.2 SC with over 100k miles, and it purrs like any good cat should. Doesn't appear to have had much work except being maintained well. Can the 5.0 be that much different?

Yes. Very different (much higher-tech) engine.