How to tighten center section turbo bolt?

[Twiglet240]

Can I tighten the nut on the T25 turbine wheel without taking it off? It seems like mine backed off a little bit, but the wheel spins so, nut sure if I can impact it, or hold the wheel maybe?

[brndck]

Welp, remove the turbo elbow and hold the nut on the exhaust side.

Also, any reputable turbo manufacturer puts a paint mark across the nut onto the wheel, so you can see if the nut has been removed. It's common in racing. Torque a fastener, paint it, that way you know it's been torqued. If the paint mark no longer lines up, or if the paint has been cracked, you know the fastener has been moved.