When my car is idling there is quite a noticeable drone/vibration/hum in the cabin - if I rest my hand on the handbrake I can feel the vibration. At take off/low speeds it also feels like the car is a little less smooth than she should be. The engine itself is running very smoothly, so I'm assuming it might be an engine mount(s).

Is there anything else I could check that might also result in this vibration in the cabin?

 

Seeing as the car is 23 years old, you’ll want to inspect all the front subframe mounts (2 vee mounts and 2 round rubber mounts at the back of the front subframe) I would do the transmission mount also. There are also 4 rubber mounts for the exhaust that probably need inspected as well. I know this doesn’t exactly narrow down your concern but, the truth is that these cars are getting up in age and they need a good inspection to keep them and you safe on the road. 6 years ago when I replaced the front subframe 2 rear round rubber mounts, it made a significant improvement with the way the car handled. Albeit this was on my then 98’ XJR with over 250k miles. Today it’s my daughter’s car with over 282K miles. The reason I didn’t replace the 2 front vee mounts when I had the front subframe out is because when it belonged to the previous owner, I had installed them when he was our customer several years prior. But it still runs and drives great today. Don’t ignore this because the reason I ended up buying that 98’ XJR from the previous owner was because the engine mounts were so collapsed that the aluminum transmission oil cooler lines had rubbed through on the metal subframe and was leaking ATF everywhere. He didn’t want to contend with it so I bought it with 234k miles on it.

 

Thanks @Addicted2boost , seem you're giving me a lot of advice at the moment I might get my mechanic to look into this.

 

Are there any good diagrams that show the subframe of the x308? I don't really know what the subframe mounts are

You didn't mention the engine mounts, are these likely culprits causing the vibration? Replacing all of the mounts you mention may start to build up to quite a cost.

My car has done about, 290k kms, not a patch on the 282k miles your daughter's car has done!

 

I had a customer come into the dealer a few decades ago with a horrible droning/vibrating noise in a 1996 XJ6.
I lifted the car to find the gearbox aluminum cross member snapped on the right side resting on the exhaust pipe.

The pipe kept the trans tail from dragging the street.

 

I didn’t mention the engine mounts because I knew you had a grasp on that idea.
A full under car inspection with extra attention to all the rubber components is a must. As long as the tech is knowledgeable, you should be able to find the issue with relative ease.

 

That's comforting!

 

I assumed that your comments were in addition, then I started looking in detail at the x308 suspension and got myself a little confused...but eventually figured it out (sort of!) I've got my car booked in next week for an inspection.

 

Hi everyone,

Which part? According to the Jaguar parts site, the transmission mount is MNC7550AB1 however, most of the OEM parts seems to claim the MNA7550AC is interchangeable with MNC7550AB1, eg: https://www.ebay.com.au/itm/126414600254

It was my understanding that the X308 XJR part was specific to the XJR.

 

Hello... You should check your center bearing on propshaft....Any play on it will turn in vibration in the cabin...

 

Hey, thanks for the tip. The vibration only seems to be when the car is stationary (in gear) or at low speeds - but disappears very quickly over 20km/h.

 

7 Reasons Your Car Is Vibrating When Idle or Stopped (mechanicbase.com)
This article may lead you to issues with your Jag.

 

I had my engine mounts and gearbox/transmission mount replaced and the vibration is gone, my girl is driving smoothly once again

Thanks to everyone for your advice and suggestions!