Turbo Noise

[Mukaniko]

Hello Everyone I have an isuzu Mu with a 4jb1t engine. im quite concerned of its turbo since when it spools what i hear is a loud whirring whistle and it also shows up when in load. but when im revving on neutral it doesn't make it.

anyone knows what might be causing this?

thank you very much!

[geeves]

3 things make turbo noise
micro cracks in the surface of the housing. If its not excessivly loud I think this is your problem and the best fix is grin and bare it. Its the wonky knees old people get which makes them grumble and groan but doesnt really slow them down.
Bad bearings. New turbo will fix
Bad heat sheild Also time for a new turbo. This is also caricterised by a whistle when you turn the car off

[Mukaniko]

Hello Geeves, does any of these 3 relate to the whirring sound only showing up under load(when i'm cruising) but not when im parked and rev the engine up?

thanks for your reply. i'll start looking for signs of the three you mentioned.

[geeves]

Some turbos make noise under load and there isnt much you can do about it. Its caused by the pressure difference across the impellor blades causing some air to go past the tips. Any imperfctions will whistle. It doesnt happen on no load as the turbo doesnt build up the high pressure.
A new turbo might fix but the turbo in my wizard has done this from new