It is not sludge buildup.

Sludge is a byproduct of combustion. It is a specific problem, not just gunk in the engine.

What people sometimes refer to as sludge problem is in fact the crankcase ventilation system, and the oil separator in that system. That isn't sludge, it is condensate emulsified with oil, producting a paste. This is likely what the reference to all the posts on the forum means, and you already determined you didn't have a problem with the CCV/OSV.

Well, my first post....
I recently bought a 2004 4.8is (cash, no extended warranty), and on the way home noticed a hiroshima mushroom cloud of smoke eminating from the rear of the vehicle after it had been idling a bit. *Here's the link.
X5 leaking valves - YouTube
I called the wholesale stealer back, who said, "Oh yeah, that's normal, I noticed that, and I called a BMW dealer friend who told me it was probably that OSV valve."

I bet the other part of that conversation went, "BUT IT COULD BE THE VALVE STEM SEALS AND WE'D HAVE TO SEE IT TO MAKE SURE, SINCE WE'VE NOTICED THIS ISSUE WITH N62's!"
Wholesale stealer thinks to himself, "NO WAY am I taking it in, I'm going to see if I can get a sucker to buy it."
Can I prove this? No, how I can I prove that he KNEW it was VSS, and NOT the OSV/CCV? *I've been talking to a lawyer anyway though. *Pretty deceptive IMO that he did not mention THE GIANT PLUME OF SMOKE that darkens the sky.

So I'm that sucker. To those buying a BMW, idle it for 5min, press on the gas, and go look behind the vehicle. White/blue smoke? Run away. We had a vehicle inspector check it out too, and they also missed it. Inspector company says it's something they would not have caught anyway. Local dealer wants 6,700$ to fix, so obviously looking into indie shops. I can't 'DIY' on this one.

I did research before buying a 4.8is, but I didn't come across these threads. All I noticed were obscure threads here and there on transmission issues, nothing systemic. However, when it happens to YOUR vehicle, it becomes a big issue. The more I look into this, the more widespread the issues seem to be with N62 engines and VSS (or valve guides for that matter). My 2004 only has 87k mi! I would expect more, and to be honest, as much as I like BMW, this is sub-par. Having vehicles last only 100k mi seems bad for business, but obviously that's wrong, since Bimmers are running strong. We are planning on keeping this vehicle I suppose. Don't know how I could 'trade-in' with this issue.

Anyway, end rant.....

So is the prevailing wisdom to ream the valve guides as well?
My thought is, depending on the 2nd opinion of the next shop, if the engine is coming out, do the guides, but if it can be done within the vehicle, just the seals. Sound good??

Once you get that far, you might as well replace the guides. All the stuff will be pennies on the dollar compared to all the other expense. But this will give you a much bigger chance of nothing going wrong in a very long time. Get a good shop to do it, and you will be ok. When and if mine go, I will be doing it myself with friends.

Let them look at the back top of the engine there are two hoses its for suking under presiure when they are broken a little bit then that can be the problem .ihad the same problems but i waithed to long an than they have to repair a hole loth more

can't be said better, I am amazed at the number of 'damn, my shit's busted, better sell it immediately and assume the dealer will fix it' posts and then see your post among others as the recipient. resale values are going down, nah, gotta be coincidence.

4.8 is a sweet ride, sorry you got boned.. if no pre-sale inspector is looking for this and it IS that easy and equal.. $8k ouch (I cracked a head once, over-heating, I feel that bill).

sticky time? (duh-wanna simplify)

Update: Well, waiting on estimate from Indie shop, but they mentioned that they had not done a valve seal job (or guide job) on the N62. I called another shop and they said the same thing. Does anyone know of a good shop in GA or SC that has some experience with valves on the N62b48???
Any help greatly appreciated :)

Surely if they are experienced BMW mechanics then they will have no problems? I did mine with only the TIS manual to help, and the only special tools I needed were for doing the valve timing.

IanP, how hard was it to do the valve timing? What tools did you need?
I'm considering doing the valve stem seals on my '04 4.4i.

Not exactly true. The oil being burnt will cause the car to run somewhat rich while it's being burnt out, and this will, over time, do damage to the Cats.

Timing is easy, I hired the timing tools from E Bay in the UK, but I think thry are cheap to buy in the U.S. They are basically just machined clamps that sit in cutouts in the cams to keep them in the correct position while you tighten the cam chain sprockets, along with some gubbins to keep the tensioners tight. You will need the TIS manual for the procedure though.