I recently passed 50k miles on my 110 P300 and had the transfer case and center+rear diff oils changed (oils were dirty and cloudy already). Shortly after leaving the service shop I noticed a low thud/clunk noise coming from the rear/center of the vehicle, exactly where the rear-diff is. It is not a repeating thud and now happens rarely when pulling away at slow speed but is more likely to happen after a cold start. I can't seem to reproduce the sound on my own (manual gear selection, different stop/start behavior, etc.) and there is no CEL or code being thrown.

I took it back to the shop to assess and as is tradition we couldn't reproduce, even after letting the car cool off a bit. They raised it up to look underneath and no visible issues either. I also was watching the the 4x4i screen and there is no correlation of the thud with the lockers engaging/disengaging.

Any idea what this can be? I read it could be the incorrect oil or wrong quantity used but this was done at a trusted Land Rover shop and they verified with the dealer that they used the correct spec. I know when changing transmission fluid the computer has to recalibrate overtime or you have reset it manually, but apparently that is not part of the procedure for diff change.

Appreciate any insight or help here!

 

If you have a rear locking differential, it uses a very specific JLR fluid, i believe.

 

Yeah my car has been doing this since new.

 

Depending on how loud the clunking is, it could be that some fastener wasn't properly secured and two bits of trim/whatever are flapping together at certain points. I would crawl under there and check. Shaking various body parts along the way. I've cured 3 of my own clunking sounds by re-securing loose trim & parts.

Good luck! Post the resolution when found, please.

 

Update: Turns out it was in-fact a Diff issue, but an odd one. The service shop found a service bulletin related to the issue I've been having, reason for issue is UNKNOWN. Land Rover guidance was to remove the fuse and double flush the oil in the rear diff. Issue seems to be resolved! If it comes back will have to do a warranty claim for a new one but I think it must be a software related gremlin and not a mechanical issue. Service Bulletin for reference below. Hope this helps and if you go to get your diff fluids changed please make sure to flag this to your service tech, might save you a headache.

 

MRMIHAI: Thanks very much for sharing this information. I am glad the TOPIX helped you.

Ugghh !! I am at 40K miles on my 2020 110 P300 and am presently waiting for the dealer I am using to obtain a transmission filter, so they may change the transmission fluid, rear ediff fluid and transfer case fluid on the same day (I hope they do not mix them up !!).

So, I read the TOPIX to imply that the problem they are addressing is that when the rear differential attempts to engage there has been some chunky gunk released within the differential during the static change which should NOT be there and thus they want to flush out all the fluid TWICE more, in the hopes it will resolve the problem.

This is the least expensive fix, which is what is done when certainty of something worse occurring is not present.

I have printed out the TOPIX and will definitely be aware -- thanks!

 

Interesting. When my P400 w/ rear locker is started in the morning, every time I stop at the stop sign 2 doors down & turn right out of my street, I get one "thump" as I'm turning. Never hear it any other time, or turning left. Don't think it's an issue yet really though.

 

Whats the appropriate oil? Anyone use liqui moly? Jlr fluid is a pita to obtain

 

This type of bulletin brings me back to my dealership days. Under investigation....Change the oil 2x. . The differential in the rear locker equipped vehicles utilizes a torque on demand design. This uses a PWM drive motor and ball ramp with clutch packs. This design allows variable levels of locking requested by the ECU. There is a special type of friction modified synthetic fluid used in these type of torque on demand units to help promote friction for the clutches. Over time, these clutches and ball ramps wear and the clutch material contaminates the fluid. We have seen excessive wear of these units for no real reason. Fluid type and quality is crucial for these units. Non locking rear diff equipped units are just a conventional differential with not much service or complex components.

 

Here is a picture of what Sarek is describing within the rear ediff, for those interested......... I do not know for certain if Magna is manufacturer which JLR uses; but, I expect they are.

https://www.magna.com/docs/default-s...rsn=6949b18f_2

Enjoy !!