07 XK rattle hunting...
#1
07 XK rattle hunting...
I have a metallic rattle coming from the rear at about 30mph which dissapears when accelerating or decelerating (or momentarily if I go over a bump). I suspect there's a screw or a nut loose in the bottom of the boot (sorry trunk).
I thought I'd found the problem when I fished these 2 nuts out of the bottom of the liftgate
which turned out to be from the spoiler. I stuck them back where they're supposed to be but the rattle didn't really go away.
Other items which seem like they could be the source - the plastic handles on the battery. The top of the mount for the nav DVD drive rattles when I hit it - it could be vibrating against the trunk lining (which sits right on top of it). The rear parcel tray rattles when tapped if the liftgate is open but it seems fairly secure when it's closed. Hoping it's not window glass.
I guess I'll remove all the trim in the boot and the spare tyre and see if there's anything rolling around in the bottom.
I thought I'd found the problem when I fished these 2 nuts out of the bottom of the liftgate
which turned out to be from the spoiler. I stuck them back where they're supposed to be but the rattle didn't really go away.
Other items which seem like they could be the source - the plastic handles on the battery. The top of the mount for the nav DVD drive rattles when I hit it - it could be vibrating against the trunk lining (which sits right on top of it). The rear parcel tray rattles when tapped if the liftgate is open but it seems fairly secure when it's closed. Hoping it's not window glass.
I guess I'll remove all the trim in the boot and the spare tyre and see if there's anything rolling around in the bottom.
#3
Now I'm convinced the rattle is coming from the right rear underside of the car. With the window down driving next to a stretch of armco barrier I can hear it pretty clearly from outside. I think a stone has got jammed up under one of the heatshields.
When the car is cold - no noise. When it's wet, the noise is there but reduced. Noise only starts when I ease off the gas after accelerating. Once it starts it won't stop until speed gets below about 25mph.
At 40mph it's really loud, at 60mph no noise whatsoever. There's one patch of road about half a mile from my house where the road straightens and flattens out and I can predict pretty much exactly where it'll start.
When the car is cold - no noise. When it's wet, the noise is there but reduced. Noise only starts when I ease off the gas after accelerating. Once it starts it won't stop until speed gets below about 25mph.
At 40mph it's really loud, at 60mph no noise whatsoever. There's one patch of road about half a mile from my house where the road straightens and flattens out and I can predict pretty much exactly where it'll start.
#4
A stone like you say in the dust shield or maybe even just a harmonic of the dust shield. I had the same thing on another older Jag and I ended up putting a rubber pad (like used to stick on equipment for feet...about an 1/8" tall and 1/2" square) between the dust shield and the place where it rattled off of....as I remember it was a pad on the spindle forging that was the shield just layed against and was supposed to basically back up/support the dust shield and instead just acted as a sounding hammer :-)
#5
On the note of finding loose nuts...I would say this is a far more troubling problem. I had a bolt back out of my brake carrier and start grinding away on the serrated wheel speed sensor and I forgot about it until your loose nut reminded me. The bolt on my new XKR sounded exactly as you describe and was intermittent as well. I reccommend you check that immediately. Look on the inside of the rear spindle assembly (you will have to get under the car and look from the middle toward the wheel to see it) and verify that none of the bolts threaded toward the outside of the car are backing out and the head rubbing on the serrated wheel speed sensor...if any bolts are loose contact me off thread via PM as there are alot of things that I am pursuing because of this and I would assume you will be very interested and should be very concerned....
#6
I think I've found the source. If I repeatedly whack the rear exhaust box on one of the front corners with my hand I can reproduce the rattle - which is coming from inside the box :/ I think it's the SAM valves rattling which may explain why it only occurs when I back off the gas.
Anyone know if there are any known issues with the SAM valves.
Maybe I should investigate some of the aftermarket exhaust options...
Anyone know if there are any known issues with the SAM valves.
Maybe I should investigate some of the aftermarket exhaust options...
Last edited by jallitt; 11-20-2010 at 12:58 AM.
#7
update: took car into my mechanic (independant). They could reproduce the noise in the rear box by whacking the pipe in front of the center muffler. You can hear the whole exhaust ring - then there's a loud rattle which sounds like a bag of loose change in the front of the rear exhaust box.
Priced new rear exhaust: local price is approx 200% of retail price in the UK or US (probably due to shipping) then add 15% sales tax on top of that.
Solution: ordered aftermarket rear exhaust from http://www.blueflameperformance.com which works out to about half the price but I probably won't see it until mid January. It might make the car a bit louder - but it should be the right kind of noise.
Temporary solution: lined the boot under the spare tyre with the thickest, densest barium infused sound deadening material I could find which has taken the edge of the rattle which should make the next 6 weeks tolerable.
Priced new rear exhaust: local price is approx 200% of retail price in the UK or US (probably due to shipping) then add 15% sales tax on top of that.
Solution: ordered aftermarket rear exhaust from http://www.blueflameperformance.com which works out to about half the price but I probably won't see it until mid January. It might make the car a bit louder - but it should be the right kind of noise.
Temporary solution: lined the boot under the spare tyre with the thickest, densest barium infused sound deadening material I could find which has taken the edge of the rattle which should make the next 6 weeks tolerable.
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