I am about to take my 2008 XJR in to the dealer for annual maintenance. In addition to totally unpredictable behavior by the intermittent windshield wipers there is a noise.

I don't believe it a problem but I am extremely curious about a noise from the rear of the car when I am gently stopping from low speeds. It is a muffled thump which sounds like something rocked forward and bumped then rocked back and bumped again. I have looked in the trunk and under its floor and found nothing.

I did have noises under similar circumstances in my 1993 Q45 when the gas tank was low. But the Jag seems to do it based on the type of stop.

All ideas appreciated.

 

Just a thought about your wipers. Are you sure you do not have them in the auto sensing position. This will wipe when it senses rain on the front glass and is very random in operation.

 

Re-create the slow bump stop for the dealer service agent, and I bet they find whats happenin. No need to diagnose and fix yourself.

 

I have the same problem with my 04 XJ8. If you find the cure, please let us know.

 

Wonder if the thumping could be tire related. If the Dealer doesn't nail it try a tire rotation. Look for a bent wheel, flat spot tire or tread seperation.

 

Noise was intermittent. I never found a way to generate it. In May I wrapped fabric tightly around all the parts underneath the trunk floor. Problem went away. Until last evening. Since investigation includes feeding too many insects I will wait a bit before further investigation.

 

I have been plagued by this same noise, from the front of my car, for months. On two trips to the FAR AWAY dealer, the noise was not there. But it is LOUD when it happens. It sounds like a piece of lead tied to a rope that hangs under the hood, and when I make tight turns or slow down, it swings back and forth, hitting the side of the car. It is driving me nuts because it is never there when I am at the dealer, but it is always there when someone takes a ride with me. Sucks for such an expensive car. 2005 XJR

 

I have the EXACT same noise. It is kinda annoying. Does anyone have any idea what it could be?!

Comes from the rear, sounds like a watermelon is rolling around in the trunk!

Perhaps it IS related to the gas tank level. Maybe the gas tank has a lot of fuel sloshing around, causing the tank to shift a little bit?

 

Don't you just hate that. Guys post a problem on the forum, get a number of folks interested and offering suggestions, including people with the same problem, and then are never heard from again.

Did he (humbug2) die going to or from the dealer? Or does he, as I fear, lack the common courtesy gene. Nah, can't be.

Sob,sob. I feel so---------used.

 

I'm almost 100% sure it's gas sloshing around in the tank. Even googling the issue reveals that it's not just a Jaguar issue--Acura MDX and various Cadillacs are plagued with the problem!

I am not worried about the noise, I just wanted to know what it was. I am more worried about the air suspension (I got my first "vehicle too low" warning message today. Yikes!)

 

Are you having any cold weather? That when air suspensions problems surfaces.

 

I can tell you what my rear thumping noise was, maybe the same? I too tore apart my boot, removed everything in there including the nav/cd changer/amplifier rack, spare tire and all the tools, even ziptied cables and hoses to nearby looms to eliminate that also. I checked the brake lines lying atop the rear lower control arm...nothing helped. The noise was only on low speeds and over slightly bumpy pavement. It turned out that the right rear lower shock bushing had failed and the shock bolt was bouncing around during slow travel at the connection. I could reproduce the noise by lifting the car on that corner from the jacking point, then lifting the rear tire (or under the control arm) so that it wasn't hanging free and the shock fully extended. Then I could use my hand and hit the bottom of the shock mount...knock sound produced pretty easily.

 

Well, I'm going to wait a little bit and see if different gas tank levels effect it. I have had suspension noises before in other cars, and this just doesn't sound as loud as those.

 

Will those of you with the "thumping" noise on slow gentle stops please describe the tires on your vehicle. Not the make, just the type, hi perf,hi wear, all season, etc?

 

Haven't died yet. Forgot to tell dealer about it last March. As noted above it went away in May then returned in mosquito season. Subsequently it became very infrequent until about 2 weeks ago and now it is frequent again.

My Q45 had noises of gas sloshing around in its tank. It took me a long time to relate the noise to an approximately half full tank of gas. This could be the problem and I will track occurrences to full/empty/in between for awhile.

No disrespect meant but it is a busy life and going to the dealer for a noise is so far down my "to-do immediately if not sooner" list that daylight never penetrates.

 

I have noticed the occaisional slight noise when coming to a stop and assumed that it was petrol sloshing in the tank.

Years ago metal petrol tanks were built with internal baffles either to prevent this happening and/or to stabilise the fuel gage reading.

Presumably plastic tanks don''t have baffles?

 

The gas tank is plastic?!

 

I have all-seasons.

Does anybody NOT have this problem?

 

My car just went in to the dealer for assorted minor things. They had it for a few days. They observed the thumping and checked all the external items likes brakes and suspension. They found nothing and wrote it off to gas sloshing in the tank.

Last night I was driving back streets in 2-9 degrees F weather with more than 40 stops that might clause the problem. It occurred once. The gas tank was 7/8 full. But the sound is the same whether the tank is 7/8 or 1/4 full.

The car has Pirelli P-6(?) all-season tires which started to get noisy at 11,500 miles. They look to be significantly more than half-worn at 12,600.

 

Re this "thumping" on slow speed stops, my vote goes to tires. Look for flat spots on 1 or more tires or tread seperation. Given how sensitive these cars are in this area, "stuff" starts to happen with well worn or hard used tires.
Hope this helps.