E46 M3 VANOS Failure - Why it happens + how to fix it with Mr VANOS - M3 CSL + Z3 M Coupe S54

Having been around E46 M3's and the S54 engine inside them for a very long time, we've always known of the VANOS issues these cars have such as being noisy, rattle, lazy actuation, broken bolts and leaking oil to name a few, and that a specialist can fix them. But why do they fail and how is it fixed?

We invited Steve from Mr VANOS down to carry out the full service on our M3 CSL and Z3 M Coupe. Steve runs us through the job, tears apart our old VANOS unit and gives us all the info.

And the proof is in the pudding when Imran takes the M3 CSL out for a drive after - It made good power on the dyno, so would we notice any difference?