This probably belongs under the engine servicing section, but bit of a story to it and Beshoff Motors and Perfect Car deserve an honorable mention.

The N62 engine is common right across the E60/E61/E65/E66 range.

A common fault is the development of valve stem seal failure. The symptoms are burning oil and smoking on idle and/or pulling away from idle.
My 2005 740Li facelift has the N62B40 block and developed this fault at only 69,500 miles. Car was purchased from Beshoff Motors in December, still under warranty.

From my research online, the seals fail for two reasons. One, the valve guides wear down, causing lateral movement in the valves, wearing out the seals.
The other reason, and the more prevalent reason is the seals go hard and loose their sealing capabilities. This is what happened my seals.
The same seals are used in BMWs smaller four cylinder engines, but the V8s run quite hot, which in my non-mechanic opinion, is what causes them to harden.
The wrong material for the temperature.

Below is my car smoking. It was also burning about 1/2 a litre every 1000 miles.

http://www.youtube.com/watch?v=ALJ5uYry31E

I examined my crackcase breather valves and they were fine, still intact. The breather hoses also had little to no oil buildup. It had to be the stem seals.

I left the car into Perfect Car Dundalk under warranty from Beshoff's. Beshoff's gave me an SLK for the week whilst it was in for repair.
Parts included new stem seals, new valve cover gaskets and new breather valves and hose.

It took them about 4.5 days, which considering the size of the job and all their other jobs was pretty good going.

The stem seals are the black hat-shaped objects below. The hat shape is actually all metal, the seal is just the tiny bit at the top that contacts the valve. They were definitely hardened. Again, 69k miles, unbelievable!























The red plastic sheaths below are temporarily installed on the stem tips, just before the stem seals are slid over the top to prevent damage to the seals.
The sheaths are then discarded.
32 seals in total, 2 on intake valves, 2 on exhaust per cylinder.





New crankcase breather valves and breather hose were also installed.



New VC gaskets.



They idled it for 30 minutes with no smoking (it used to smoke on idle after 3-4 minutes) and no smoking the short bit I've driven it.

There doesn't seem to be a thing these guys can't do, highly recommended.

Beshoff's paid for the repair in full, which by the way was EXTREMELY good value from Perfect Car, approximately a third of what independents in the US charge.

Critical oil seals failing at 69k miles is a joke from BMW. Feels good to have a very common fault rectified for vastly less money than reported online. All round a good result!

Always good to share a GOOD story for once and those involved deserve some publicity. :wink: