Good vibrations...NOT!

[boothc]

Can anyone help me with this? about 6months ago when the the engine was hot i could feel and hear a vibration between 1000 and 2500rpm when i was in neutral. This has steadily got worse over time and it now does it as soon as the engine gets warm and you can hear/feel it when driving also. I've had a chap look at it and he says it appears to be coming from 2 metal pipes running from the bottom right of the radiator to somewhere under the engine. Has anyone else had the same problem who managed to sort it? Also can someone tell me how to find the ABS sensors on each wheel and if there is a simple way of finding out if its faulty. The ABS appears to be coming in at slow speeds or just before the vehicle stops. Its been on a diagnostic machine (apparently) at the garage and he claims the computer hasn`t logged a fault. The ABS light on the dash has come on once or twice but goes off once the engine is restarted. Ideas?