Hi everyone. I'm new to the forum and also new to owning Jaguars. I'm proud to say I just bought a 1998 XJR and I love it! Runs great. Anyway it has about 128000 miles on it and is making a humming sound from the back. When I first bought it if sounded like it was coming from the front but my mechanic drove it yesterday and said it's coming from the rear. I jacked up the rear of the car and both rear this have up and down movement. Not much but just enough to notice. There isn't any side to side movement, just up and down. What could this be? Bar wheel bearings? I noticed the pitch of the hum changes when letting off the accelerator. Any thoughts?

 

Exhaust leak resonating through boot ?

 

Yes.




Which also might be a worn differential.

Welcome aboard, by the way.

Since you have a 1998 XJR you should post in the 'X308' section.

Cheers
DD

 

Welcome to the forum kevin_pianoman,

I've moved your question from XJ X300 / XJR to X308 forum.

This is the place for questions about your XJR and Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

If you eliminate rear wheel bearings, diff and suspension bushes, another cause of resonance is split or missing rubber exhaust hangers (arrowed red and blue) allowing metal-to-metal contact:



One of each of these on each side. The 'L' shaped one is a common failure.

Graham

 

Thanks for the input so quickly. I don't believe this noise is anything with the exhaust, but I will check it out. The humming reminds me a lot of a wheel bearing, but could both be bad and have the exact same amount of movement? I'm just not sure about the pitch changing when on and off the accelerator. Is that what a bad differential does, or could it be a bearing in the rear end going and cause the play in the rear wheels? What kind of cost am I looking at If it does have a bad differential? Thanks again.

 

Also, is there a way to check the fluid level in the rear end?

 

Hi
Glad to be here, just joined.
I saw someone querying a rear hum - unfortunately that is what I am experiencing. I have had the car checked over by two independent jaguar specialists and the diagnosis given is worn bearing on the diff. Had most possibilities checked, and fluid replaced but cause and hum remain apparently diff.
I have had my xjr since new and love it, and wont go without it and do not intend to replace it. Its runs beautifully.
I did have to replace the engine 3 years ago and used a replacement engine from eurojag in UK. It seems that the 1998 engine was not 'lined' and actually was a fault but Jaguar never informed me,anyway the new one is lined and cost a bargain 1500£ and 1000£ to install.
Was wondering if there were any experiences of replacing rear diff as it seems now required.
Any advice or experience most welcome.
Cheers
L

 

I just refurbished the rear suspension a few months ago and the diff was out. If you paid 2500 pounds for the engine, that mean you love your car; this is what I recommend:
-find a cheap low mileage rear suspension including the diff., it must be from the same type of car. Or you can try to change just the diff, keeping the other suspension parts.
-change all the bushes and possible also the shocks (the lower bushes fail usually), as it will be easier to do it with the suspension down
-there are some tricky jobs, the long bolt of the wishbone is a pain to remove, also the lower bolt of the shock. There are some plastic and metal washers, be sure they are replaced in the same place and order
-sandblasting and powder-coating of the most suspension parts will be a future credit for the car, I did it
-check all the nuts/bolts for the right torque, use copper grease when refitting the bolts back,for future jobs
-check the front seal for leaks
-new oil inside, 75w90 or w140

 

Sound advice thank you. Will see if I can source a low mileage rear susp incl diff from an xjr and go from there - if a job is worth doing its worth doing well, so your detail suggestions are most helpful.