Let's talk valve stem seals and piston rings

Apr 6, 2018
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#1
Yet another mystery blue smoke thread
I know! But I'm really here asking your experience with valve stem seals and piston rings. Who has replaced them, at what mileage, what were your symptoms, how common is it, I've seen the thread at https://bmw.spoolstreet.com/threads/valve-stem-seals-becoming-a-normal-thing.396/page-2
I'm starting to wonder if I'm in this boat. I'm about to order the seals but I'm also apprehensive, I'd hate to do the work for no reason. Also, should I replace my cam ledge bearing seals at the same time? Car is a 2007 and has never exhibited symptoms but if I'm in there anyway might as well, does anyone have the updated PN?
So to get down to the issue, the car has 101k, originally never smoked, only had a light burning oil smell when coming to a stop or idling. Then i blew my stock turbos. Replaced with VTT stage 2. Fast forward 8 months I can now see the blue smoke during deceleration after any kind of over half throttle pull, and its defintely a very noticable smell. Ive replaced the entire pcv system with external dual catch can kit with head port block off kit from VTT this past week, performed a walnut blast (valves looked good), index 12 injectors, still the same if not worse. I performed a compression check this morning and I get the following results
Cylinder 1 = 200
Cylinder 2 = 200
Cylinder 3 = 195
Cylinder 4 = 200
Cylinder 5 = 200
Cylinder 6= 185
I'm a little worried about number 6 being an outlier. It's not much but still concerning. I've heard of people having cracked ring lands and I'm really hoping this isnt the case. Theres no real good way of checking exhaust valve stem seals (without removing turbos) or the piston rings obviously. So I'm unsure how to continue addressing the issue. Its worsening despite my best efforts to fix it. Any and all information is greatly appreciated.
Thanks guys!
 
Jan 28, 2018
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#2
You need to do a leakdown test.

Neil
 

Bnks334

Corporal
Dec 1, 2016
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73
New York
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#3
Have you don the most obvious thing? Pull your air pipes off and check for oil?
 
Apr 6, 2018
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#4
Good point!
I'll get a leak down tester asap.

Yes I've checked for oil, they are all clean.
 
Jun 27, 2017
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#5
I was having the smoking issue a little while back and during my research basically nobody (n5x platform) who did the valve stem seals had their problem solved -- it came back same day or days later. 90% of the time solution was replacing turbo (seals) and 10% of the time it was PCV.

Turn that MHD burble off if you haven't already. FWIW, new turbos fixed my issue but it also hasn't been 8 months yet
 
Jan 28, 2018
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Parts unknown
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#6
Pressure it up and listen for air leaks out the exhaust, or intake. Check for bubbles in water etc
 

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