N63 Cam Gear Installation

[DrVirz]

Hi All,

I have just fully rebuilt my N63 in my E70 X5. Upon first start there was significant misfiring, after checking the usual culprits I decided to pull the valve covers to check the timing. All 4 camshhafts were out of timing I am yet to check if the valves were hitting the pistons, but will get around to it and report back.

All cam bolts were new and torqued to 30nm + 90 deg. Important to note when setting timing prior to installing the motor back in the car, one of the gears did slip a few times when hand-rotating the motor. I then tightened this cam bolt slightly more than 90 deg which stopped the cam gear slipping.

Is there anything (other than the clamp force of the cam bolt) that stops the cam gear rotating independantly of the camshaft? Am I completely missing something here?

Thanks all

[Sophisticated Redneck]

Are you applying anti seize grease to only the front washer on the bolt? The back of cam gear and camshaft faces that mesh together must be absolutely clean of any oil or grease, use carb cleaner and qtips to remove any trace of oil or grease on the surfaces as this is a pure friction fit. Again only the front of the washer on the bolt itself should have just a thin film of the anti seize.

Also check your torque wrench and make sure its 30nm is really 30nm by comparing to another torque wrench. Slipping on just hand rotation is crazy as the force on this friction fit when hand rotating are nothing compared to what this goes through at 6k rpm.

[DrVirz]

Yep, applied copper anti sieze to the washer at the head of the bolt only. I did clean the contact surfaces at the back of the cam gear/front of shaft with acetone however I probably didn't give it as much love as you have mentioned.

I will double check my torque wrench, I have another that I can compare against.

I will try and get a camera into the cylinders today, hopefully I haven't damaged any pistons or bent any valves.

[DrVirz]

Update.

Got a boroscope into the cylinders. It does not look like there has been any piston/valve contact. However the intake/low side of some pistons either look damaged, or possibly have slight carbon (doubtful, pistons were well cleaned at assembly) or liquid buildup. The exhaust side of each piston looks fine. See attached photos of cyl 1-4, I will post cyl 5-8 in another post.

When hand rotating the motor to move pistons to allow me to get good photos, the cam gears and cams seem to have gone back in timing. Assuming this is the cam gear returning to locked position and the internal pin engaging? Shouldn't this happen when the engine turns off?

[DrVirz]

Cyl 5-8 attached.