95 xj6 3.2 knocking noise. Any ideas?

[Dominicc01]

Last year I was driving in a car park, and heard a strange noise from the back of the car. Going over a speed bump very gently caused a loud banging from the rear (I think) passenger side. This then happened every time I hit a pothole Took it to be looked at, and they could see nothing wrong with it. There was a leak from the diff, and the bearings needed replacing. This was later sorted.

The banging from the suspension stopped as soon as they had looked at it and found nothing wrong.

Then it started making a funny noise over winter. Wheelspin in the wet would occasionally produce a knocking/banging sort of noise from the same place. Once or twice it sounded more like the diff, but usually it sounded (and felt) more suspension related. It has become more frequent, and happens when moving off - both travelling straight and turning. It doesn't always happen. Sometimes it will happen several times in a journey, sometimes once, and often never. It is occasionally one "clonk" but can but three or four.

i took it for a service today, and the mechanic looked over it and can't see anything wrong with the suspension. He suggested it could be driveshaft related. Anyone experienced this or got any ideas?

Edited by Dominicc01 on Monday 7th June 19:55

[S2 Giles]

i'd be guessing at stiff UJ's on the drive shaft

May sound silly but have you checked the rubber exhaust hanging brackets

[TurricanII]

a wild guess - Replace all the suspension bushes and track rod ends? Also check the battery/spare wheel is not loose in the boot in the battery compartment!! The latter is not a wild guess. When you take your foot off the gas and you think that some transmission item is knocking, it could just be the battery rumbling.

[Trooper2]

Jags and Land Rovers use a rubber driveshaft coupling and they are known to wear out, look into that.

Edited by Trooper2 on Wednesday 9th June 04:06

[oversteerxj12]

There is a funny thing can happen with these cars.
Just in front of each rear wheel you can see the A-frame bushes which the entire rear subframe is hung from. The bushes have a metal inner which bolts to the floor pan and a metal outer pressed into the A-frame, with rubber in between the two. It is quite common for small stones to be flicked up into the bush, getting wedged in the gap between metal inner and outer and causing the bush to become effectively solid, leading to an intermitent loud banging/thumping noise.
Probably why it dissapeared without trace as soon as it was looked at - because the stone fell out as soon as it was jacked up and the bush was un-loaded.
Sounds silly I know but it is quite common and worth a good look and clean-out.

Edited by oversteerxj12 on Wednesday 9th June 11:26

[Dominicc01]

Thanks for the replies.

I will look at the bushes as a first point of call.

I don't think it is battery / exhaust. These would sound when hitting bumps and other vertical movement, but this only occurs with lateral movement - and generally only on setting off or with kickdown (as opposed to the original banging, which was with vertical bumps and which went away after the car was jacked up).

[varsas]

Exhaust knocking can be very odd, depends how the hangers have failed. My friends SD1 would occasionally knock when turning right, we both were convinced it was the diff but no, turned out it was the exhaust. It's worth taking it to the local quick fit and having it looked at just in case. Will cost you very little. Even if it's not the exhaust they still might be able to tell you what the problem actually is. If they can't I would say it's a job for a Jaguar specialist.

Edited by varsas on Thursday 10th June 08:29

[Dominicc01]

varsas said:

stuff

Yeah, the mechanic I use has looked all over it, checked the exhaust etc, and can't find anything. Sadly there is no Jaguar specialist in Jersey that I'm aware of. The main dealer over here is horrendously expensive, and they have a terrible reputation - they're worse than useless.

Edited by Dominicc01 on Thursday 10th June 09:03

Edited by Dominicc01 on Thursday 10th June 09:03

[Fibres]

I had a similar fault on my car (3.2SE) and it turned out to be the bush on the bottom end of the shock absorber, it has a metal casing and wears, the amount is very small and I've since hear of unscrupulous garages just rotating the bush through 90 degrees as this will stop it for as short time. The job is quite awkward and time consuming but by far the best solution. Get your mechanic to check for the slightest amount of movement.
Best of Luck