Hi all, Let me start of by saying Im a looong time mechanic on diesel and american muscle. The mini I'm working on is my nephews 2008 r56 non turbo. He replaced the timing chain and tensioner and didnt tighten the crankshaft bolt so I'm pretty sure he has some bent valves. Ive got ZERO compression in number one cyl. 120 in no.2 110 in no. 3 and 40 in no. 4 The question Ive been searching answers for is...When I go to replace the head after the valve job, do i have to time the vanos system and the eccentric cam that contols lift when I lock the cams in place. If those all have to be timed to a certain point when the cams are locked in whats the procedure to do that. Ive scoured the internet for a couple days including this site but im unable to find out for sure. Also a question Im pretty sure of the answer... is it possible for the eccentric cam to be so far out of whack it would cause my compression readings? Thanks of any help in advance!!!!!!!

 

When installing the VANOS unit on both the intake and exhaust camshafts on the N12 engine, they can be placed on in any position initially; finger-tighten the bolts however.
Then you have to torque down (see long procedure in Bentley Publications service manual) those units with an angle protractor and torque wrench.
From there, timing is required when locking down the camshafts at a certain crankshaft rotation position and you loosen the VANOS, and re-torque them in phase.

There's a lot to read regarding such; make sure you have the tooling, and detail prior to attempting.

- Erik