Hello,

I have a 2006 XJ8 that used to belong to my mom. She first got it as a Lease. Since it is brand new sometimes it has this feeling as if the front wheel has something rubbing against it, then it would go away and not happen for a while. So it would only happen sometimes. About 4 years ago I had the front brakes and discs replaced, this grinding sensation still remained; still sporadic. I should have brought it up the dealer's attention when it was under warranty but since it is so sporadic I would think it remedied itself. This Friday I got it back from a local mechanic who changed my air compressor. When I got it back the grinding sensation was stronger than ever, and on braking there is a vibration that I can feel at the brake pedal. It doesn't do it all time but it does it about once each day that I drive it. I took it out a second time today and drove it around the city, it didn't do the grinding or vibrating noise at all. Yesterday I took it out on the highway and a little city driving it didn't do it.

Today I noticed that between the brake discs and the interior there is a metal part, so I gently pushed it in (towards the car) maybe that's what was rubbing against the brake.

I might ask the mechanic since I have to go back; the shop forgot to put 4 screws that hold the plastic shield at the front of the bumper, they also left one of the tabs from the plastic shield sticking out. Now I'm out 4 original Jaguar screws.

Anyways I was wondering if anyone has experienced something like this? I tried searching previous posts but could not find any that matched this issue.

Thanks in advance for any tips or ideas.

Frank

 

Think another shop is needed, or better yet do your own work.
Brake work is pretty simple

 

The part of your description that caught my attention was that it only did it once per day/drive. I'm thinking you are feeling the air suspension compressor run. Had this exact same issue with my car, the rubber and spring mounts can get put together incorrectly, or wear out, and you feel a vibration in the steering wheel and pedals while it runs. The compressor typically runs at the start of a drive, once you accelerate over 25 mph. It will run until the reservoir is full again, or if you have leaking springs it may run a lot more. "Normal" operation is for about 30-60 seconds of runtime before it's finished. If you slow below 25 mph it will also stop running (Jaguar didn't want the compressor to run and passengers to hear it while stopped).

 

Thanks @mhamilton , That's great info. I'm going to go back to the shop tomorrow. I also noticed they forgot to attach 2 screws at both corners of the plastic shield that goes under the bumper. I wish there was a way to get the compressor to come on, I tried parking on an un-level surface with the engine running, but it did not come on.

 

Good idea. Any shop that leaves not one but multiple screws, clips or other parts missing, AND installs a splash guard with the tab out is likely to have assembled the suspension for the compressor incorrectly. Mike is right. There are rubber bushings, springs and washers that MUST be installed in the correct sequence. I am always amused to consider that the AIR supension has a pump with conventional springs and bushings for ITS suspension. The irony!

All of this is found in section 204-05 in the Shop Manual: "X350 - Workshop US003 - 2. Chassis" - available from a link in the stickies on this forum. Here is a pic with the way the parts mount, ABOVE the brace, with only the retaining nut below if I recall correctly.

Give them hell - This is not what you pay people for, to have to take your personal time to go back and get it repaired correctly.


The inset shows the order that the springs and bushings sit over a threaded shaft. Any incorrect assembly will allow the pump to touch metal. Think of a small compressor touching metal and then the sound you hear. If that fits, this is your answer. That section of the manual will also have a troubleshooter and an explanation of what conditions will cause the pump to run. Your obviously works or your would be suffering the dreaded "Car too low" or "Air Susp. Fault" messages.

 

Thank You @Blairware !

I’ll be going to the shop in a couple of hours. About three years ago I took the route to replace the front shocks with Arnotts. I’m thinking I should have done the conversion to the non air suspension. It was a lot costlier at the time. From reading the repair manual there is a lot that can go wrong with the air suspension.

My car looks just like your past 2006 XJ8, I have the same wheels. Mine is not the long version though.

I”ll post an update after the fix.

 

UPDATE:

Hello,
They took down the wheel well and checked the installation. I moved it up and down, it seemed to be isolated but I don't really know, It's the first time I see that. After it was on the lift we drove it and I heard the noise, it did three times in one drive which is unusual. The mechanic was a heavy guy so maybe it had to lift the car more often. I told the owner (main mechanic) that the first day I drove it out from their shop it made a very loud noise. I figured the part was "breaking in". Then he told me to drive it a few days to see if it gets better. I wish there was a way to get the compressor to work on demand, it would make diagnosing it easier. I'm going to take it again in a week, on Monday.

This morning when I drove it, as soon as I got down to 24 mph the noise appeared as Mike (in the previous post) indicated.

I liked this shop because they are honest, and I was referred to them by my previous Jaguar mechanic (who was good, and did all the work himself) but when they're like brushing you off as if you are some old lady that doesn't know what you are talking about it may be time to find a new place. I feel like taking it to the dealer and telling them to uninstall it and install again, but they'd probably ask me to buy the part again. I might start going to the dealer again even though they charge a lot more for the parts and have all kinds of fees, such as a "shop fee", "disposal fee" etc...

While trying to look for problems around the wheel I noticed the bushing for the upper control arm has deteriorated away. I thought the noise might be from there but then it would do it all time time. I'll attach a picture of it.

Bushing has gone away.

 

If the joint is still tight, the dust boots can be replaced.
POLYBOOTS from Bulgaria, a dozen was less than $20 to my mail box.
14 x 31 x 23 mm is the size i used till i replaced the arms two+ years later

 

Sounds like you're pretty much determined it is the pump. If the unit isn't running excessively it should be okay. In my experience the pumps can be a little more vibrational when they're new and the sealing ring is tight, but at the same time it fills up the reservoir very quickly. Having it on the lift used up the reservoir air to level the car when put back on the ground. If you want to force the suspension pump to run you can try jacking up one corner of the car, which will cause it to start exhausting air and then it will almost be guaranteed to replenish the reservoir on the next drive.

Like Wingrider said, the ball joint dust boots on these cars are known to fall apart every 50k miles or less in hot climates. I also replaced the front upper ball joint boots. Just recently found that the new rear tie rod boots are cracking again, right on schedule. Joint will be fine until dust and water get in there and wear it out. If you catch it early and replace the boot you can save it.

 

Hello,

I feel the vibration on the pedals when the compressor comes on. I now realize that when the car was new it was the air compressor coming on what I was feeling. It still makes a quick noise (like a Brrrppp) for a second when it shuts off. The shop owner told me last week to keep driving it a while and come back if it still had the noise. I might take it in. A friend (my Corvette mechanic) offered to put in the missing screws. He also fixed the second plastic splash shield that connects with three screws to the first plastic shield. He's a really good mechanic but unfortunately doesn't work on Jaguars. I'm going to look for a new shop for the Jaguar. My Corvette mechanic advised me to just leave it the way it is, with the noise. It just bugs me to have a noise I never had before. Then some people tell me the car is 14 years old to which I say the part is brand new!

 

@mhamilton @Blairware So I took the car last week and left it over night at the shop. I asked the owner to listen to the noise the next day and let me know if he thought it was normal. He changed the part for another one and now the noise is gone! I still feel the vibration stop when the compressor shuts off, but I felt this when the car was new. When it was new I didn't know what this sporadic vibration was. Actually I didn't make the connection until mhamilton's post here. The vibration feels stronger than before so I guess the original part got weaker over time and I didn't notice. Thanks for all the posts and help!

 

Glad you got this sorted out. Cars are full of wonderful, interesting noises that can be hard to identify, like an intermittent squeak that drives you mad and you can't even place where its coming from. In your case, knowledge is (was) power. Once you knew what it was you were in better position to resolve it.

Happy motoring!