I've just spent a couple of hours fitting a high level axle breather kit, topping up the rear axle and fitting the wading plugs, I also emptied the fuel sedimenter whilst i was under car. Upon starting her up (300TDI) she started fine as expected but seems to have developed a high pitch whistle coming from the frount of the engine, now I don't believe that its related to the work I just did but it is a coincidence! Anyway does anyone know what this is most likely to be? Looking at the belt tensioner appeared to have a bit of a wobble. Is there a bearing in this? as I suspect its gone as there is also a little movement in it, would this be the cause of the whistle?

Sorry I forgot to mention that it only whistles at idle, it stops as soon as you rev the engine. Could it be the Turbo?

Bump.

If its at idle could be the belt does it go away if you bring the revs up or when it gets warm?

Just at idle, as the revs come up it stops, and yes even when warm. It doesn't sound like a belt slipping, more like an old whistle kettle. I'm assuming there's a bearing in the tensioner and I'm assuming there shouldn't be any movement in it either, so I'm assuming this is a replacement job.

puppysandwich said:

Just at idle, as the revs come up it stops, and yes even when warm. It doesn't sound like a belt slipping, more like an old whistle kettle. I'm assuming there's a bearing in the tensioner and I'm assuming there shouldn't be any movement in it either, so I'm assuming this is a replacement job.

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Yes probably the belt and/or the tensioner try dribbling some water on the belt if it stops its the belt, use a cup not your mouth though the noise will come back quite quickly though but it will elliminate any bearings.