Hey so for the past few months I have heard this really loud and obnoxious whistling sound whenever I take my foot off the acceleration. I hear the turbo then about 2 seconds later I hear the whistle. The whistle is also audible whenever I keep my foot at the same pressure on the acceleration too. I have recently changed my belts but that was after I could already hear the noise. Any suggestions to what it could be would be much appreciated!


EDIT: The car does not have to be moving, it happens in neutral aswell. It sounds like it’s coming from the front area of the engine.

 

That whistle sounds like a "boost leak" to me. If you can, trace your air intake hoses and check each one at the coupler/clamp. Take carb/throttle body cleaner and give it a real quick spray at the suspected area. If the car idles up or tries to stall, then you've found the leak. Since you have a turbocharged model, the troubleshooting will be a bit more involved. It can be a number of possibilities, the main ones being loose/broken/worn induction tubes, or a leaking blow off/bypass valve.

If you can get yourself a "boost leak tester" that would help. What that does is, with the help of a compressor, fills the entire air induction system before the throttle body with pressurized air. In doing so, it forces any leaks to make themselves known, via hissing, whistling, or any other noise you could think a rubber/plastic component could make. I've had one "fart" at me, that was a hilarious repair LOL

 

Just as a heads up, we are in North America so could never get the T6 Rangers you have in Australia, ours are all Petrol and non-turbo until 2019

There are a few Australia Ranger forums that would be more familiar with your Model, include the year and engine size for best results