My poor car is back at the dealership yet again for the exhaust whine, but had also developed a thunk in the rear with low/light throttle application and release, as well as a distinct grinding noise from the rear at 1500 under load. Sounds like a diff issue to me, but what do I know.

For context, the diff sounds started in October, when it was hot out, but couldn't get it in for service until now, when it's currently below freezing. It's still under warranty, for another 3 weeks.

The advisor informed me that the thunk and grinding is because I don't have winter tires on the car. Said "without having winter tires on the rear diff is locking and the traction control is trying to keep the tires from spinning which is where the grinding noise is coming from. Winter tires are $1924.00 installed."

Before I take off my earrings and ask a bystander to hold my purse, I want to make sure there wasn't a TSB or something that I can hand to them and ask them to look at. I vaguely recall reading other reports of diff failure on the forum over the past year of research and for some reason I am also remembering a TSB on the diff? But I could be wrong, so just want to make sure.

Thanks all.

 

could you duplicate this with traction control turned totally off? I would think this would bypass the "locking" issue the advisor is pointing to.

 

I don't appear to have anything related to diff issues. Here's a clunk related to the transmission output flange, which doesn't sound like what you're describing.
https://www.dropbox.com/s/lec9xkk5vo...402V3.pdf?dl=0

 

I imagine so, and that's such an obvious idea, of course I didn't even think of that. I just informed them that the issue occurs at slow speeds in warm weather in a straight line as well, and figured that would be the end of that line of reason....but alas. Thanks for this, I'll suggest this.

Yeah, not quite, it doesn't happen when shifting gears - but thanks for that. I have saved so many of your docs over the past year and you've been such a huge help!

 

Ask the advisor if you buy the tyres and the fault persists will they reimburse you the price of the tyres, since they've clearly sold them under false pretenses. I've driven my "summer" tyres in freezing conditions and never noticed any thunks or grinding - I call BS.

 

Haha, yes, my husband suggested the same thing. I don't think that quickly on my feet, unfortunately! And despite the satisfaction of eventually proving them wrong, I cannot stomach paying $2k USD for a set of winter tires.

 

May well not be your problem, but everything I have read (except from scm, above) indicates that the oem Pirelli P-Zeros and other Summer tires are unsafe below 45 degrees.
They become hard and brittle,and may crack. They provide poor grip in the cold and can be deadly in snow and ice. Considering where you live I am sure you get very cold, icy, snowy weather in the Winter.
My solution (in Boston, MA) was to fit all season tires. A set of Michelin PS A/S 4's cost about $1,100 fitted and balanced - not close to $2K because they were not fitted by a Jaguar dealer.
So, my advice, for what it is worth, is that if you intend to drive the car in the Winter, you should definitely get a set of AS or Winter tires. You should get them fitted somewhere other than your Jag dealer.
Forget asking for a refund from the dealer. You really need the tires regardless.
Then you can determine whether there really is another problem

 

I'm still waiting for our P Zeros in the rear, to crack. Have already bought UHP all season tires but the darn things just won't wear out (since I had the car aligned).

 

I would ask them to do a diff fluid drop and refill to A) see if the pinion seal is leaking and B) check the condition of the fluid for shiny bits. It’s maintenance that should be done anyway and may lead to a better diagnosis.

 

My PZ rears were aboout 50% gone by 8K miles even with alignment, and no burned rubber.
The fronts were still decent.

 

Not driving it in the winter, but thank you. It's supposed to be in storage currently, but we had nice weather through November. So when I called to make the appointment when the cold weather stuck around, it was another month wait to get into the dealership. She doesn't leave the garage under 50 def F.

Yeah. I asked them to at least check for leaks and to check the fluid to see how the fluid color was (I haven't worked on this one myself so I'm not sure, but I don't think they can tell if there's any metal flake in on the plug without draining), and they sent me a picture of the undercarriage with the comment "This is the undercarriage. Differential looks good!" lol.

My next request was for a quote for the diff to be flushed and filled. I figure at least I've made my best faith effort to allow them to resolve the issue, and if the diff fails in the near future, at least the issue has been thoroughly documented prior to the warranty expiration. I can't imagine if they do find some metal bits on the plug or gunky fluid that they would just drain and refill and call it a day. I hope.

 

Before I take off my earrings and ask a bystander to hold my purse,

Hahahahahaha