My 1995 X300 has started to develop a high pitched whining sound when the engine is started. The noise persists for a couple of miles or so then stops, but returns intermitantly only to appear to 'switch off' after a few seconds. The noise seems to be coming from the top front of the engine near to or from the alternator, though it could be from something adjacent to it as I can't pin it down exactly. Taking it to a garage would present a problem as the noise, though always there on start up, isn't there all the time, so you can bet it wouldn't show itself at the gargage!
Anyone any ideas as to what it might be?

 

The next time it making the noise on startup, take a 2 or 3 foot length of wood, old broomstick handle, stick, yardstick, 1X2 almost anything you can hold to your ear and the other end to the alternator and other components. You will able to determine what is making the noise by holding one end of the wood to different components such as the alternator and water pump and the other end to your ear. Be careful of spinning pulleys, drive belts etc.

Doug

 

Thanks Doug, much appreciated. I have traced it to the air pump! I have now posted a question re' this.
Thanks again.