Magnesium valve cover

[BEN99W]

Hello

I have a 2006 3.0Si Auto originally from Japan (Im in New Zealand).

I'm looking to get on top of some preventive maintenance, and having gone through the service history, there's no sign of the valve cover ever having been done (although there is no Japanese history) and it has the nearest whiff of a leak. So is it acceptable to retain the magnesium Valve cover and just replace the gasket and the bolts? There is no obvious corrosion on the cover but I've seen some people suggest the face of the cover corrodes and then never reseals so swapping to an ally one is prudent. Is this right?

Also liquid gasket or no liquid gasket?

Cheers

Ben

 

[Z4Mariner]

Yes, use sealant (sparingly) on the valve cover side.

My 2006 3.0Si is also a "silver top" N52 with the magnesium valve cover (VC). I replaced the VC gasket and the aluminum bolts at 89K miles in the first year I owned the car. While the general outer surface of the VC was oxidized, the mating surface of the VC was still well-machined, and it had been sealed with 'liquid gasket'. After cleaning, I used a very thin application of sealant on the entire VC sealing surface - no leaks in over 3 years since.

My reason for renewing all the gaskets to the VC (VC, Valvetronic motor, ESS) was oil seeping at the ESS seal - that seal is designed to install from the inside of the VC. I was surprised that the VC gasket had been replaced once before, with sealant on the magnesium VC but not on the aluminum head. It seemed strange because the date on the OE gasket was within months of my car's manufacture date. Since then, I discovered that BMW had an inspection campaign for early N52's in the US - they checked for "cam bearing ledge wear" from the steel sealing rings that seal the oil supply to VANOS, and that required replacing the VC gasket.