Originally Posted by BMWM.D.
This is the reason we don't need turbo timers on these cars.
Try this test: stick your key in the slot and hit the start button to activate KL15 mode (all dash lights on). Do not start the engine. Turn the heater on full hot (84+) with the blower speed in the middle. Push the gas pedal to the floor for at least 10 seconds. This activates the cooling system bleed mode. The pump will run through it's various speeds for 10-15 minutes.
If the noise you've been hearing is the coolant pump, then you'll be able to tell during the bleed procedure, as nothing else will be running to cover up the sound. If the pump sounds normal, then it probably isn't your issue.
As far I have owned Turbocharged cars, I know only PORSCHE 944t
(aka 951)has a after run for coolant and the earlier 5 Cylinder Audi Turbocharged engine 2.2 inline 5 and the inline 5 DOHC turbo.
Performing that is when your bleeding the system and you activate the pump to "self" bleed the system, it does not do this when you shut off / seize engine operation, this will not perform this operation after driviing the car at a normal basis.
Correct me if im I wrong....the turbochargers "thrust bearing" floats on engine oil right? so if you are driving to your destination and are on boost by the time your reach your destination and shut off the engine, the oil pump is no longer pumping oil....causing coking and people that follow the CBS on the car and believe that the engine oil will last 15000.00 miles is main receipe of early turbo failure.
Most Turbocharged cars have the oil feed for the turbo's on top and return oil line below ( vertically) and coolant banjo fittings for coolant run horizontally
Mini Coopers that are Turbocharged have the auxillary water pumps.... I have been wrong, so please enlighten us where is this Auxillary Water Pump on MY N54 E90 located at, since we work on these cars day in and day out.