Vibration on 1991 facelift 4.0 coupe

[CliveRothwell]

This problem shows up after 7 or 8 miles from cold as a permanent vibration felt through your heels and also the steering wheel. All levels seem normal. MPG has fallen to 22.5 from 25.9mpg over the past 18 months - Stoddart revised crank sensor fitted 18 months ago. Other than that, the car drives spot on but it's now getting on my nerves. Any thoughts please?

Thanks

Clive

[steve_m]

That's a weird one! All I can think of is a dodgy tyre that is going out of balance as it gets up to temperature, maybe you have a flat spotted one? Been late braking into corners recently?

[Brakebuster]

faulty viscous cooling fan ?


BB

[CliveRothwell]

I deliberately didn't mention the new P600s all round! Noted for being noisy, I'm too sure if it is the tyres. A longer left or right turn will induce the symptom yet I don't necessarily think it is a wheel bearing as they seem smooth.

Why do you think a viscous fan BB?

[Brakebuster]

if the bearing is gone, or a chunk out of the fan , when it kicks in after a few miles when the engine heats, this can induce a vibration , being viscous , it doesn't go on and off like an electric fan with temp


BB

[CliveRothwell]

hmmm good thought - I'll have a look and report back......................

Many thanks

[PaulGover]

I've found a worn suspension bush can allow play that develops into vibration - indeed my X350 is about to go to have new bushes precisely because of this. The main characteristic is that the vibration will sometimes go, until turning the steering wheel or a change in road surface induces it again.

[CliveRothwell]

Thank you Paul - I like your thinking especially as it does seem to "come and go a bit"

I'll investigate further.

[PaulGover]

Hmmn. Just back from the local dealers. They couldn't find the vibration, and on a test drive neither could I. And all the bushes were OK - one split, but nothing serious. So in this case it looks like it might have been old wheels losing their balance. I'll try getting the alignment checked, as the front tyres were wearing on their outside edges - I'd put that down to the supposed play in the bushes, but now I'll blame it on old bushes settling/pot holes/the misalignment fairy.

Nice dealers (Ridgeway Jaguar, Oxford) - spent time, and three road tests, and didn't charge me anything. Propbably helps that I bought the XJ from them, but still, not often you get something for nowt.

[CliveRothwell]

Fault found! It IS a worn NSF wheel bearing! That is excellent news as it could have been more expensive..................can hardly wait to get it done now!

[CliveRothwell]

So, job done for just £163 at Nene Jag Specialists in Peterborough and it has TRANSFORMED the car! So smooth and quiet, it clearly had been creeping up on me for quite a while without really noticing. In fact, it's so good, I took it to work today for the fun of it!
Happy Days......................

[ptjs1]

Clive,

Glad to hear that you've sorted it. It's funny how a small problem can spoil the driving enjoyment of a Jaguar. And when it's fixed and that magic ride comes back, we fall in love with the car again! I felt the same when I changed my block-hardened and wall-cracking tyres with some new ones.

Enjoy the drive!

Paul

[greeban]

I too had the same 'wow' when I had a new set of pirelli tyres fitted, probably exacerbated by recently fitting the spare which was an original unused alloy, so had to use it on the car and had not realised that this had worsened the lack of grip at the back - with new Pirelli's the car is transformed - I had never experienced this level of transformation before and I now know that tyres harden over time which significantly affects the handling, particularly on heavy powerful cars such as the XJS.