Someone must know PLEASE help

[supercarman]

Hello everyone,

I Have just bought a fantastic 2001 S-type 4.o sport.....only problem is that when driving from cold there is a severe knocking noise from the front like a susspension problem but heres the thing....... after covering 7/8 miles it STOPS and sound quite normal......i have just had changed the passanger shock and the drivers wishbone bush....two specialists cant find the problem and i am avoiding the main agent like the plague as this sort of problem eats hourly charges....PLEASE PLEASE advise.....

[Simpo Two]

supercarman said:

i have just had changed the passanger shock and the drivers wishbone bush

Before the knocking noise started or afterwards?

[supercarman]

The car had a knocking noise on test drive, this was appaerntly due to the wishbone bush which was subsiquently changed, from memory this solved the knocking at least when driving home (the car was already warm/driven by the time it was ready for collection)...the knocking i beleive came back a few days later but as already mentioned only when cold and it was not as servere as when the wishbone bush needed doing..

[UncleRic]

supercarman said:

this was appaerntly due to the wishbone bush which was subsiquently changed,(the car was already warm/driven by the time it was ready for collection)

Are you 100% sure the seller (assuming it was the seller who did the work) actually changed / fixed the fault?

supercarman said:

two specialists cant find the problem

That's worrying, did you ask them to double check the WB bushes..

Exhaust mainifold (totally un-educated guess)? Maybe some bolts have snapped, might explain why the noise stops when everything has had a chance to heat up (and expand a bit)?

[Tame Technician]

Does the noise occur when you go over bumps and ripples in the road?

If so its suspension. If its just knocking all the time, then could be engine or drive train.

If its suspension S type are know for front anti roll bars wearing, people change the bushes and it shuts it up a bit (usually still noisey on a caold day), but untimatly the bar itself and the bushes need to be replaced.

Previous owner may well have confused wishbone bush with anti roll bar bush, or even his garage may have mis diagnosed it in the first place.

If your a bit handy you could remove the front anti roll bar drop links and do a short road test to confirm the noise is gone. But dont drive arround for any length of time with the anti roll bar dosconnected.

[pete5570]

Sounds like the seller was aware of the problem and the fact that the noise goes after the car has warmed up,hence the fact the car was already warm when you went to pick it up. I would be looking at the engine/drive train, I don't think suspension noises would just stop after a few miles, it's possible that something in the engine in early stages of wear could expand when the car has been running and the noise/knocking would stop. Hopefully it will be the suspension, but i would have the engine check also, it could e why the car was for sale.

[Simpo Two]

If I was in your position I'd get it to a nearby garage with lift and ask somebody to give it a sound pulling about underneath while it's still cold.

My 2001 S-Type used to rattle a little when cold (timing chain I think) which stopped after a mile or two.

[S2 Giles]

I have just had a similar problem. All 4 upper wishbones had seized from lack of use as it had stood for a while and had 1000 miles pa put on it. When they replaced the bushes they noticed one of the arms bush holes was oval from wear. If yours hadnt been noticed, or thw rong bush was replaced, could this still be the problem ?

The thing i'm stuck with is that you say "severe" knocking. If its severe then im not sure its a wishbone bush and also why would it go away, mine got worse when warm.

Have you looked at the engine mounts ?
or how about the front crossmember bolts ?

[Fleckers]

sounds like exhaust vibration to me