A new noise

Just heard a new noise today.

It happens just before I hear the turbo start to whistle.

The sound is not to loud, perhaps a little less than the turbo whistle.

Its a high pitch sound, not as high as the turbo whistle, it kinda sounds like spun bearings. Kinda like the sound from a waterpump or alternator bearings.

Any ideas as to what to chek?

I tried to make her do it when she was parked by revving the engine but it would not. seems to have to be under load...............

Thanks.

Maybe turbo bearings

Exhaust manifold gasket? Not had this on a Landie but had an Astra Turbo Diesel that squawked when it came on boost and the manifold had come loose.

I had a similar problem a few months ago and suspected worn turbo charger bearings. However it turned out to be a blown head gasket. The noise got louder when I put my foot down because the gasses were being blown out at higher pressure and making a louder noise.

You've got a TD5 with one of those centrifuge oil filters haven't you? Is it the centrifuge? I can hear mine whirring sometimes after the engine is off.