At 122,000miles, the breather will need replacing. Do it next time you replace the air filter, since it's under the same cover. Or when you go back in to the manifold to locate the leak...

The breather was not originally a service item but BMW added it the service schedule after a number of turbo failures related to blocked breathers.

There's a couple of different breather options - a "loo roll" filter type (better at remove old from crankcase vapours but prone to clogging and requiring frequent replacement) or the newer "vortex" type (not as good as the filter type but shouldn't ever get blocked). You pays your money and you makes a choice....

Here's my old (filter type) after 200,000kms and the new vortex type I installed.



The old filter was totally clogged...

Re. the cabin smoke (diesel fumes) - that narrows it down to an exhaust issue. What sort of replacement manifold was installed (sorry if I've asked this before) - an OEM stainless type or a cast iron version? If it's the stainless type, it's likely cracked again. It's a feature...

If it's the cast iron type, it's likely got a leaking gasket, either at the manifold to turbo connection (most likely) or at one of the manifold to head connections.

It's also possibly an exhaust leak at the turbo turbine output port - where the exhaust pipe is bolted to the turbo - or the EGR connection - either at the manifold or on the EGR valve.

Given that all this had to be removed to replace the manifold, it's all possibly a leak source, especially since you say it leaks when you drive hard, i.e. the exhaust pressure increases...

Also note that some of the cheaper cast manifolds are not machined very well - the gasket faces are not well finished.

I used the M57TU-specific manifold from X8R when I replaced mine - this is the one I received...



And FWIW, here's my post about replacing the manifold...

https://xoutpost.com/1142332-post39.html

__________________
Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)