Rebuilt turbo whining when cold, what is it?

[burn4005]

Hi Guys,

We've put in a couple of freshly rebuilt and balanced -5s in a mates car and we are getting this whining sound during spool with light load pitch follows load with a bit of a lag. During boost and high load I can't hear it, it may go away but also may be drowned out by other noise. also it only does it when the car is cold. after 10 minutes running it's completely gone.

theories are:

a) Turbine outlet flange exhuast leak (heats up and seals properly) or somewhere else?

b) Inadequate bearing lubrication (oil warms up and it comes good)

c) Turbo is out of balance/excessive bearing play (turbo warms up and comes good, but I'd expect it to be loud during boost as well, unlikely to be play, they are brand new cartridges and felt perfect)

 

anyone seen this before or is it normal? If it was a T51R-SPL I wouldn't be worried but it sounds like a big turbo spooling from low down.

sounds like this but fainter. in our case you have to listen for it:

another example:

 

anyone had this before? Videos don't say what it ended up being or how they fixed it.

Edited September 5, 2016 by burn4005

[hypergear]

Assume there are no leakage. 

It's sounds the turbine shaft has too much run out. 

[camsr34]

What does too much run out mean?

[burn4005]

wobble in the radial dimension when spinning. like if you spun a shaft that was slightly bent.

 

thanks hypergear, I'll check for leaks first before I am prepared to entertain the thought of a bad brand new turbo core. once it's warm its perfect. hopefully I'm just shit at doing up bolts.

 

Edited September 6, 2016 by burn4005

[camsr34]

Thanks for the explication mate

[hypergear]

Once its worm, the bearing housing expands and gives an few extra thous of bearing clearances for the shaft run out. So the turbo becomes quiter.