I have had a sound now for quite some time but have hesitated to ask because (1) it is difficult to adequately describe sounds and (2) it only occurs at a very specific instance.

I guess I would classify it as a road noise sound and the only time I hear it is going over certain speed bumps/humps while driving fairly slowly. As I hit the bump there is a sound like two blocks of wood being knocked together (almost a hollow sound) and it comes from the right side directly in front of the passenger seat. It almost sounds like it is coming from within the glove compartment. This does not happen with all speed bumps but ALWAYS happens with the ones on my street for some reason. I tried approaching the bumps at different speeds and different angles but have not been able to isolate why this happens on some bumps and not others.

Does this make any sense to anyone and, if so, any suggestions as to what I might look for?

Thanks,

Doug

 

Is there perhaps something mounted behind the glovebox that has worked loose?

The X308 has the BCM mounted there and it is heavy enough to make noises if one of the bolts has worked loose.

 

Sway bar bushings?

 

Where do I look to see these? Any diagrams, pics, etc?

Thanks,

Doug

 

Doug,

After my last two miserable failures at diagnosing described sounds, I'm keeping quiet on this one unless you drive by my house so I can hear it.

Graham

 

Just a quick update. I passed by the local independent (Mina Gallery's dad) and had Rene take a quick spin around the block. He heard the sound instantly and just as quickly said it was an upper bushing--apparently pretty common. However the car has just about 30,000 miles so that seems surprising.

Anyway he thought the repair would be less than $200 which I will try and get to in the near future.

Doug

 

Very interesting. It would appear that bushings (and some mounts) are among the many parts of these cars which begin to fail because of elapsed time rather than accumulated mileage.

 

Not second guessing but maybe for future reference: a similarly defined issue (and sound) can happen when the stabilizer bars that run diagonally across the corners of the engine compartment get loose.

 

+1

 

I will second that also on the engine compartment stabilizer bars. I had a popping sound that drove me crazy until I discovered that these were the cause. I snugged them up and the sound disappeared.

 

Still a mystery. I brought the car into my local independent Jaguar guy and he replaced the stabilizer bar bushings as well as lower bushings (I do not know precisely which ones). The car handles great and feels solid as a rock. HOWEVER, there is still that weird noise that sounds like two blocks of wood being hit together at the instant I encounter a speed bump or hump. This happens at even very slow speed--car barely moving.

The second the right front wheel meets the upward bump there is this noise that sounds like it is coming from somewhere behind the glove compartment and almost like somewhere within the dash area.

The mechanic is suggesting the next step may be to look behind the glove box and/or remove the center console and see if something is loose.

Does anyone have any instincts or suggestions as to what the noise might be?

Thanks,

Doug

 

I was looking through parts diagrams to see what might be behind and/or below the dash and found this figure. Item 4 is something called instrument panel brace and I wonder if this piece is loose.

Does anyone know how to get to this brace?

Thanks,

Doug

 

A new suspect has emerged from other discussions of the "speed bump clunk".

The RHS motor mount. Sometimes, the fastening stud on the bottom which can only be seen from underneath, has elongated or the nut has loosened.

Or, the motor mount itself might be on the way out.

The LHS motor mount might be allowing the RHS motor mount to collapse and then come up again ... when it does, the nut hitting the frame would clunk. Or just the movement of the engine down because of momentum while hitting the speed bump can bounce that nut away from the frame rail and when it comes up ... clunk.

On the XJ series there is a rubber plug that has to be removed from the subframe rail to see it. The XK might be the same.

 

I don't know about that. To me it still sounds like it is coming more from within the cabin or right below the dash rather than from somewhere outside and low like suspension or motor mount.

Doug

 

Your ears are much closer to the car

 

I suspect where I said "stabilizer bar" it is different than your mechanic (and admittedly my terminology may be incorrect). Your mechanic replaced stabilizer bar bushings (aka sway bar bushings: sway bars run across the width of the bottom side of the vehicle). The bars I am referring to go diagonally across the top of the engine compartment corners and are visible from the top-side of the vehicle with the hood open. They have no bushings. If those have not been tightened down give it a try. You have to remove the plastic cowl to get to one end of the bars (which also means you have to pull wiper arms off). Your description fits this issue to the letter and I hope this helps.

 

Jascus--I know exactly the underhood braces you are talking about. I can verify that the ends that attach to the strut towers are tight and have been too lazy to remove the cowl but have tried grabbing the braces and moving them. They both seem tight but I suppose I should remove the cowl to see what is going on at the other end.

Is that a true 5 minute job or is it one of those 5 minute jobs that turn into an hour? I can see that there are about a half dozen screws at the cowl that need to be removed (most under plastic covers and a couple exposed). Are the wipers seemingly as easy to remove?

Thanks,

Doug

 

My vote is on this brace. It meets all the symptoms you discribe: Under the dash, caused by wheel motion, etc.

You'll probably need a small two pronged puller to get the windsheild wiper arm removed. After that, its a half dozen screws.

 

That seems to be the obvious culprit but I just assumed that the braces would be noticeably loose and they are not. But I guess I will try to remove the cowl and take a look.

By the way, what about the brace for the instrument panel that I asked about and showed a figure of in a previous post?

Doug

 

Doug: Don't know about the dash brace, but I would check and tighten the three top of the dash bolts under the left and right 'shark fin' grills, and the center pop off cover. Also be careful with the oval cowl finisher covers. The tabs on each end get brittle and can easily break off.