Reconditioned turbo keeps whistling - is this normal?

The engine management light came on in my 2012 Nissan Qashqai 1.6 diesel, which has done 42,000 miles. RAC diagnosed and exhaust and throttle control actuator fault, and felt that the turbo was about to fail. £200 tow bill. I was quoted £1300+ for both repairs (£600+ for exhaust and throttle control valve, £700+ to supply and fit a reconditioned turbo, which they said would be guaranteed 12 months). We have requested confirmation in writing. After 7 working days and many telephone calls, we paid the bill and they delivered the car back to us. When I drove it the next morning, the turbo is still making a whistling noise. The garage took the car back, but three hours later left it back on our drive with no explanation. When I again phoned the service manager, he said it's normal for a reconditioned turbo to whistle. I had decided to sell the car, but with the turbo whistling so loudly, it will prove impossible. I have already written to the dealer principal, but have yet to receive a response. What's your opinion?
The reason a turbo whistles is because not enough engine oil is getting to the turbo bearing to lubricate it properly. The reason why that happens is that the engine has been shut down too many times when the turbo was red hot and the effect of that will have been to carbonise the oil in the turbo bearing oil feed and oil return pipes, eventually restricting the oil flow to a trickle or even stopping it altogether. A turbo should never ever be replaced without also replacing the turbo bearing oil feed and oil return pipes. After a long motorway run, after a long ascent or after towing, it's always wise to idle the engine for a minute or two to allow engine oil to lubricate and cool the turbo bearing as it spins down. A feature of the Renault 1.6 DCi in this Nissan is that the stop-start will not shut the engine down automatically if the turbo is too hot, but if you physically switch it off that is when the damage is done. In normal suburban motoring, it won't get hot enough for you to have to worry about this.
Answered by Honest John on

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