I'm in the process of replacing the head gasket in my 2001 X5 3.0i thanks to a botched job by the previous owner. Lots of stuff was done wrong, not the least of which is missing fasteners and improper connections.
I think I have most of it figured out, but a couple of the small vacuum hoses have me confused. There are two fittings at the back of the intake manifold for 3mm hoses and both were disconnected when I started working on it. So I'm not sure which is which. I believe one goes to the valve for the secondary air pump, and the other to the crankcase vent valve.
I tried to use my wife's Z4 3.0 as a reference because it has the same M54 engine and has never been messed around with. But on her car, ALL of the vacuum hose fittings on the back of the manifold are capped off and not used. So that was a strikeout.
Next, I looked at my 1999 528iT with an M52TÜ engine - which is very similar to the M54. On that car, the hose from the secondary air pump valve goes the fitting with the check valve, and the one from the CCV goes to the other (See photo).
Is the M54 the same? And, to add to the confusion, it looks like the CCV has been replaced in the X5. It has the foam sheathing over it, which I understand is an aftermarket addition to keep it from freezing in cold weather and was not installed at the factory. The fitting for the vacuum hose on the CCV is capped off.
So, do I remove the cap on the CCV and run a hose to the manifold, or do I leave the cap and plug the fitting on the manifold? Do I even have the fittings correctly identified?
Note in the photo that the manifold is laying upside down on my workbench.