Rear "whomp"!

[nurgle]

The car is off back to the dealer (only a few miles from the independent, going by lorry to avoid any use of the diff). Beyond the oil sample, nothing else done to the diff. I'll update what happens re part warranty and getting it fixed.

[nurgle]

So........

My diff was replaced in Sep 17 under the extended warranty. The original car's diff failed. This diff had 2 years parts warranty.

In mar 19, the diff had failed again and was replaced by Jaguar (fully paid for by them). However, because Jaguar replaced the diff under parts warranty, the warranty period does not start again but still ends in Sep 19 i.e. the 2nd part does not come with any warranty beyond that of the part it replaces.

This, according to 2x Jag dealers and the independent, is standard practice.

This is worth knowing as for example, if your car is under its 3 yr manufacturers warranty, 2 weeks left to to run and a part is replaced, there is only 2 weeks warranty on that part.

Car now transported back to the independent who will look to address the diff issue!

regards,

Rob

[nurgle]

Final update

The car is now fixed! When drained, the diff oil was "spent" - discoloured and with the viscosity of melted chocolate.

The Limited slip diff clutch plates were unable to correctly engage with each other due to the highly viscous oil, thus resulting in the "whomp" as they managed to do so. The fact that the problem lessened as the diff warmed up was due to the oil becoming less viscous once warm.

Oil replaced with Castrol BOT 720 which is recommended for F type diffs.

The entire driveline is now quiet and much more refined.

regards,

Rob

[Philskill]

Sounds good news, and good to hear your story.

What's the service interval for the diff oil, 2 years seems low to be in such poor condition, given I've never changed diff oil on any car I've ever owned! My Evoque may be the first as its reaching 9 years old this year!

[GARETH]

Just a quick question. Is the differential filled to the level plug, or is it filled with a specified amount?

I ask because on my other JLR product ( D4) all the diffs, and gearboxes are filled by amount of oil and not to the level plug.

[RPSN]

Limited slip differential (LSD) oil change intervals are every 64,000 miles/48 months.

Without LSD it is 160,000 miles/120 months.

LSD oil capacity is 0.84 – 0.86 litres.

[GARETH]

I just ordered some Motul Gear 300 LS 75W-90 Fully synthetic limited slip differential oil. 15% off at Opie oils using code PAYDAY. I think its time I changed it.

[RPSN]

Can't fault it.......Opie Oils are great and they're really helpful too.

I recently had a new pinion seal fitted by my Jaguar main dealer and the limited slip differential oil was renewed at the same time.

[GARETH]

Just update this thread to say oil change has worked wonders on mine. No more thumps!