constant turbo 'whistle' only in manual gears

[omodos]

Hi there, did a bit of 'mountaineering' with the x5 last weekend and noticed somethin odd, I had the car in Manual 2nd or 3rd depending on
how steep the slope I was going down was. The turbo has whistled since I got the car it usually whistles when i hit the gas and then off when I release the pedal,BUT on the steep slopes going down and in the gears I mentioned it would whistle regardless of whether i had my foor on the gas pedal or not....

(PS 3.0D auto e53 2004 with 39000miles on the clock) any ideas would be much appreciated

[Laurence]

This is normal.
Diesel engines have unrestricted air flow (where as petrol engines have butterflies to restrict air flow). Coasting down a hill in gear 2 or 3 will cause the engine RPM to increase and therefore air flow across the engine will increase (the pistons will still draw air into the chambers and exhaust it), this in turn will cause the turbo to spin up.


The whistling noise however shouldn’t be too loud as this can be a sign of an air leak or turbo imbalance.

[omodos]

Thanks for your input, you know your stuff it seems, whistling is not too loud to be frank but was just a tad worried as usually in the past when coasting down hills mountains always had windows up, so could not hear much, ok thanks again, car is going strong, apart from the mystery coolant loss every 1000miles about half a teacup of coolant, and my chopstick are cluttering and need sorting....keep in touch, diesel owners are few and far between...

[Fraser]

No 'turbo whistle' from my 'O5 3.0d. Up hill, down dale, off-road, on-road.

[omodos]

Interesting, maybe the 05 was more evolved than the rest? I will check the hoses tonight and see, had one such scare where a hose came off some part of the turbo or wastegate and power of car was pants.....post is in x5 world somewhere