Intermittent whining noise from rear

[xjjohn]

For the last week I have had an intermittent whining noise from the rear of my 2017MY AWD BDE, although now it seems there all the time.
I thought at first it was the LSD again, as this was replaced last year....however the noise is evident when the car is stationary with the engine running!
I have checked the active exhaust valves and they seem to be working ok, there can't be much else under the rear / centre of the car to give a whining noise like this??? Sounds similar to a motor / fan but there is none around that area?
Any advice, comments or suggestions will be gratefully received,
Many thanks.

[mike020150]

Noises can be notoriously difficult to diagnose because the sources may not be located where they initially appear to be. However, the first thing to check would be the fuel pump located in the fuel tank. At the most optimistic interpretation, it's possible something is vibrating in sympathy with the pump rather than the pump itself failing or trying to pump against a blocked tank filter. Mike.

[xjjohn]

Many thanks Mike, good point...I'll get this checked out..I'll post on here when? it's resolved...

[xjjohn]

Well...long story short..ish..!! after 8 seperate attempts at the main dealer in MK to get this resolved...they still couldn't...I kept explaining to them that the whining noise only occurs when the engine has reached operating temperature! This was heard by service advisor and tech on arrival one visit... However they let it sit each time I took it to them (90 mile round trip each time!)..then they would start it when cold and say they couldn't hear anything...(I knew they had let it sit a while because of my Jaguar Remote app..)At last they looked at it while warm and said it could be supercharger, coolant pump or water pump? This time they had the car 4 days and informed me after the fourth day that it was the water pump bearing and had replaced it...another 45 mile trip after arranging transport to collect the car. Upon arrival to collect I was assured fault was fixed, started the (cold).. engine, but...3 miles down the road the noise was still very much evident!!!! It was pointless returning the car to them, (they had just closed) as if they couldn't resolve it after 8 attempts them a further visit was pointless...I emailed ( one of many!!) the aftersales manager, dealer principle and service advisor that the fault was still there, I also contacted Jaguar Customer Support...
The DP asked me to return the car to them, yet again..I then advised JCS that I would take it to another main dealer in Coventry, who I had purchased Jaguars from them before, and had greater confidence in them. The first visit to them was for initial hearing of the whine when warm.The service advisor and technician heard the noise and the car was booked in a week later. After receiving a call to say they had resolved the issue, I arranged transport (112 mile round trip..) and collected the car. The temperature was still warm and no whine noise apparent!! It turned out to be the auxiliary idler pulley bearing...
Apologies for the long tome!!!

[Marineng]

Thank you for explaining this techical minefield so well. I presume that the fault was completed under warrenty. I have just taken out an extended warrenty for my 2017 AWD as I have had a couple of repais completed under the standard warrenty. Paul

[xjjohn]

Hi Paul, thank you for response, luckily I took out a Jaguar extended warranty in April as the two year used car warranty when I bought the car in March 2019 expired..Last year I had a replacement LSD followed by a rear wiring loom, and then realignment of the rear valance, caused by incorrect fitting of rear panel when they replaced loom!! Now a new water pump, (obviously not required as wrong diagnosis!)..and now the auxiliary drive belt pulley bearing..hopefully no more issues for a while, but I was contemplating getting shot of it!!!! Also just noticed the bonnet is not aligning well with the shut lines, and passenger door touches panel when opened!!! No doubt caused by the 'mechanics' not closing the bonnet correctly from the centre. I have seen a good video on line on how to realign the panels, so that's my next job!!!
John.

[mike020150]

A classic example of how difficult it can be to track down the source of a noise. Thanks for the detailed explanation. Mike.