P38 Vibration problem: help please!

4.6HSE auto. 116k miles 1998. Developed vibration/resonance through whole car over last three days and I am mystified as to what it is. Most obvious at 30-40mph when vehicle vibrates enough to rattle body fittings then dies away as speed up.

Vibe feels as though either a shaft is unbalanced or a u/j is going or engine is losing a cylinder but b*gg*ed if I can work out what cause is Feels as though engine is missing a cylinder, its that kind of vibe........

1.Visual get out & get under check of shafts, U/J's and all underside reveals nothing obvious.
2.No clunks or clonks when selecting gear, moving along or gears change.
3.Kickdown,sport mode, all gerabox functions OK.
4.Engine seems fine when stationary revs freely no strange sounds or rattles.
5. No fault displays (yet.......!)

Feels as though something is out of balance!!!! over 40mph its not so bad but doesn't go away.

Mystified by it but definitely something is out of whack. Suspected possibly engine running on less then all cylinders when under load but all power still seems all available (risked it upto 100mph, no problem). Took a quick punt on some injector cleaner as had to do a 90 mile round trip : no difference, plugs seem Ok all healthy colour. Has anybody any suggestions what to start checking next? Thanks.

Has the rubber split on the track rod end ball joint thingys?? I had to have my P38 MOT'd the other day and I had been getting a slight vibration at speed through the steering and it felt as though the vehicle was jumping about the road a bit at certain speeds.

I was pretty sure it was the track rod ends and had it in with my specialist for a pre-MOT inspection to make sure it passed and because the rubber had split on the ends dirt and crap had got into the ball joint giving it a little play etc, had both ends replaced and everything tracked and all was fine again - it flew through the MOT no probs either - me = happy!

-Wills

Hi, worth a look but cannot see anything untowards. Vibration is not really appearing to come through steering system, wheel is quite steady compared to ,say, unbalanced wheels, more the whole car has this vibration. Thanks for the tip but just going to have to keep looking. Still looking for any advice from out there.