Greetings all. I have not yet posted on my other XJ8 post yet as I've encounter issues with my daily driver. I have an issue that just showed up in the past day. At 50-70 it was making a very odd noise as well as almost a vibration. The vibration was so bad I couldnt go that fast had to keep it at 45. NOW a clicking noise is coming from below the car. Weird thing is you can only hear it when I am not stepping on the pedal. I have included a video where you can hear the noise happening throughout my parking garage while I am not on the gas plus some pictures + video of below. What you will notice in the video of below is the clicking seemingly happens when the car was sitting off just after I stopped. It would get quieter and each click farther apart the longer I waited. I cant tell if something is wrong with the Exhaust or with the Drive train therefore causing the weird vibration and noise. Also the exhaust is oddly curved down but maybe thats how its supposed to be, seems off. Please let me know what you think and link me the pages that have already been posted on this topic if there is any. Thank you

Google Photos Shared Album

PS, I have no check engine light on so I can't just check codes. PSS, its not tires as they've been recently replaced along with the rims a week prior.

 

Hi Vegang,

Your vibration scenario seems to fit accounts from other members experiencing issues with the drive shaft (prop shaft) centre support bearing.
That might be a wise place to start your investigation.
The clicking could be that the bearing race has started to collapse.

 

Understood. If you listened to the video did you hear that it only happens when the gas pedal is not being pushed? If so doesn't that sort of eliminate that as the drive shaft is turning the wheels/ w the wheels and in turn it should make the noise either way?

 

I hear what you are saying.....Bearings can be funny as they might only make a noise under certain load conditions, so effectively different when the engine is applying power through shaft rather than just freewheeling.
You might also find the bearing noise is different when accelerating versus decelerating as the bearing is under load but from the opposite direction.
That being said, you might also possibly have a U joint issue on the prop shaft, that when you have torque applied the U joint is held in position but unloaded it might be allowing some play to become evident. That too would throw the prop shaft out of balance as it might be rotating concentrically.

The transfer cases can also be a common weak point in the AWD models, generally making a increasing whine as they age, or if really bad a grinding sound. But that is less likely a source of vibration unless the output shaft has developed significant play.

 

@h2o2steam the second video shows/sounds clanking dead stopped with camera looking underneath the car

 

Hi Dell, your right...sorry Vegang....(the curse of looking at these things during a short break at work, I only got to play the 1st clip).
That sounds curiously a lot like some heat expansion or contraction within the exhaust system as if it is loudest in the mid floor area of the car there are no valves or solenoids located there.

I am puzzled with the vibration at 50-70 Vegang is reporting......Dell, do you think he might have had a heat shield come loose?
That might now be vibrating with higher speeds and air currents under the hood and car and partially unsecured might be in contact with something an ticking as it heats or cools?

 

My first thought was the ubiquitous loose heat shield on X's. But, the continued clanking at rest had me stumped. And in the video it was rhythmic although the OP said later it changed as the car cooled. It almost sounded like a loose piece of a belt that slapped something but the repetition was too slow for that. I still sort of lean to a heat shield.

@vegang try post 10 & 11

https://www.jaguarforums.com/forum/x...ausing-253682/

 

thank you both for conversing over the issue and helping me narrow this down. Really trying to figure out if it's a cheap fix that I could do myself before taking it in somewhere as I just dropped $700 on new tires so the wallet is dry. Going to check the heat shields as that would be pretty ideal getting a pair of ramps today to be able to get under. The only thing I can't understand is why it ONLY happens when gas is NOT actively being fed by the pedal. I under fuel injection so of course when not being pressed fuel still is getting injected at a smaller amount which makes it even weirder IMO. Especially as a loose heat shield would seemingly rattle the entire time but I don't fully understand heat shields yet so that could be my lack of knowledge. My next concern is the rattling that just started and gradually got worst over 2 days from 50-70. I was thinking it could be the new tires however I had tire vibration prior because of my completely bald ones and when I got the new ones there was ZERO rattle for 3-4 days. Plus the noise underneath the car started at the same time as the vibration. I am wondering if I can put it in park and have someone slowing step and release the gas while I'm under to see if I can pinpoint it today as well. Saw the post you linked and checked out what people were saying on I believe the transfer case fluids possibly needing a change as well as checking all heat shields. I'll get back to you guys tonight or tomorrow. Thanks@Dell Gailey @h2o2steam

 

The difficult heat shield to reach and check is the one between firewall and rear bank exhaust manifold.
using some heat resistant material to create a packing wedge is useful to help isolate whether a shield has become loose.

 

SO I actually have some weird updates.
I sat under the car for about 30 mins yesterday and found a few odd things. Seems I have a small small oil leak not a huge deal I don't believe, but also seems I have a transmission leak as confirmed by a tech when i got an oil change the other day. I'm not sure if a trans leak could be whats going on as I haven't researched nor had one before so I'm just throwing that out there.
Some other things I noticed is about 4-5 bolts missing on various things under the car. The exhaust pipe hanger dead center of the car was not connected at all so I'm guessing that could be some of the noise I'm hearing. I also noticed a heat shield in the lower engine bay (have to see it under the car) had a bolt rusted through so it was really connected and I could move it with my hand. Plus a random cable that's not plugged in anywhere??
Even with both of these found I still don't believe they are the source of my sound/vibrations. Reason being is before I even checked under, the sound changed from the clanking you heard in the video to more of a belt noise. I only got one decent video of the new sound so I will upload to the same album Google photos shared album

 

Re your transmission leak, if you get under the car once the front is on ramps, you can easily tighten (gently snug) a lot of the small lower transmission bolts that are easy to reach. It's maybe a 10mm or even smaller, can't quite recall anymore. That helped my leaking transmission quite a bit from where it was sort of self-draining through the gasket onto the garage floor to no drips over the last month of just sitting without being driven.

 

@Dell Gailey @h2o2steam I could use a little guidance with the latest find. Took it to a local shop I trust and they claim the new wheels I put on from a year newer junked x type are not completely round. Weird thing is this issue happened around 4-5 days AFTER i got the new rims but they claim drive shaft is perfect and so on. Nothing wrong with car appartently. The clicking/thumping sound is so loud that I dont understand how that would come from the wheels. Just could use some input

edit + the fact the first shop that put them on did not catch the error somehow...

 

How could that sound occur when you are stationary and crawling under the car if it was your wheels?

 

I never got to update this post however I did resolve it kind of. Turns out the shop that changed my wheels & tires didn't notice the bolts needed to be switched to a different type and they started all backing off. I noticed one day while this problem was happening because I drove home and felt like my wheel was going to come off. Low and behold all 5 of the bolts where hand loose and about to pop off. Owner of shop drove to my place and tightened them all and noticed the issue and I got those replaced no issue since. HOWEVER something I am about to make a seperate post on is how I'm having a kind of fishtail issue happen that I BELIEVE to be tied to my lower driver side control arm.

 

If the "fishtail" feeling is when you power on a fairly lengthy sweeping on or off ramp (left or right) while applying power and it feels like the rear end is going to come around you (it won't) it's the rear upper control arms. Look up posts by member Thermo who pioneered the adjustable fix (Volvo parts). We call the fix Thermo'd.

 

Heard thank you dell, I had thought it was the front lower control arms due to missreading a different post maybe so thanks for clarifying. Theyre definitely going lol