mbsl98

Around midnight last night, picked up my 2007 530XiT (80k miles) from outside airport parking where it had been sitting for 2 weeks. In last few days, temps were pretty cold (teens at night), and 15" of snow the day before I got home. Started fine, warmed a few minutes while I cleaned some snow, then onto 50 mph highway. Within a mile, I noticed what looked in mirror like light snow bring blown from car and billowing behind. It appeared white and light weight, with large volume, as seen in mirror in headlights from following cars. However, I realized there was really little or no snow on the car to blow like that, It kept up as large volume of billowing "white" and within another 2 miles, the low oil warning came up, and then the real warning - oil below minimum, add immediately. I pulled off to side of Mass Turnpike and called for tow. Never got motor fully warmed up and never got an oil pressure warning. No particular smell of burning oil. I think all of the oil is leaking into under shield and then being blown back past hot exhaust, etc. Rear of car is entirely covered with fresh oil.right across whole tailgate, nothing different near exhaust, and no indication that the oil came through the tailpipe. Tow truck delivered car to middle of my unplowed driveway, where it sits today until I snowblow drive and move car into garage (after adding a few quarts of oil - would be nice to have a dip stick for that). Then I want to see if I can get some identification of problem before it goes to shop. Therefore, this long message.

In engine bay, it all looked clean and dry from top view last night, nothing near the oil filter housing, etc. However, I could see fresh oil on top of air shield under engine bay by looking down beside right wheel well and motor with flashlight. Left side of same shield looked dry. I know that the oil pan was starting to seep, but I had the water pump replaced 1k miles ago and the shop thought it pan looked normal and not in need of attention. FYI, water pump change was preventive, with no issues. My real questions now are what areas are most likely for DIY home inspection. I can run it up on ramps, but it is cold and snowy here and age of owner doesn't suggest a very intensive search I am thinking this must be a leak from a limited number of likely locations. Any hints?

mbsl98

quick update: in light of day and end of snow storm, it now looks as if oil is being burned rather than a major exterior leak. It started a bit hard (after adding some oil). Slight stumbling and smoked (oil not water) at start and then continued to smoke (at lighter rate) in driveway. Motor sounds good but is not quite smooth.

Aside from a head gasket, are there some other pieces that can fail without notice and while not working at all hard? It has been running great right through the trip to airport, then immediately after starting (after sitting for 2 weeks), it was in this condition. Anything that could have frozen or gotten clogged with wind driven snow while sitting? Moisture that accumulated and caused a high pressure blow-out on something?

jgt

I'm guessing your crankcase breather valve froze, failed and sucked oil into the intake manifold.

mbsl98

Breather related sounded good for a while, but.... After getting comfortable with it running in driveway, I took it out on road. At light throttle, it ran very well, the skip seemed to disappear, the check engine light went out, and smoke seemed to be clearing as if it was burning off the accumulated oil throughout system/exhaust. Just as I was convincing myself that it was something related to freezing and not a mechanical failure, I tried using more throttle. This was after about 5 miles of running around local roads at varying speeds but pretty light throttle and fully warmed. When I pushed it harder, it tripped something and reverted to a big cloud of smoke, check light and heavy skipping. It happened right around the time the 3 stage intake would have started opening either 2nd or 3rd stage (3-4k RPM, roughly). At that point I limped it home and parked again. It still seems like something related to breather/ PCV system, in that it creates some sort of path for oil to get sucked into induction system, but I don't understand that area well enough to pick something specific. If this was my Porsche, first choice would be the air/oil separator, but not sure just what BMW design is. Ideas??

jgt

Sounds like your crankcase breather valve failed or is failing. This created a big enough vacuum to pull oil into the intake manifold from the oil return line that goes to the crankcase.
If you pull off the intake manifold, it should be covered in oil.

KyleB

Oil separator should be integrated into the valve cover on your '07 N52. If that is where your problem lies, you need to look into replace the valve cover.

mbsl98

Thanks. I believe the vent is the likely answer and have it booked into local shop now. Very relieved that it is likely not as catastrophic a failure as it seemed at midnight in a snow storm.

mbsl98

Just a final update to close this. The separator and all related hoses (3 on this version, 4 on earlier ones) were replaced and everything cleaned. New spark plugs (now at 81k) done while things were open also, as the plugs were pulled to see where the oil was getting to inside engine. The usual pressure testing did not define the separator as problem, but all plugs were then pulled and found well oiled so the intake was then pulled and it was full of oil, so no real alternative except separator. Parts (excluding optional new plugs) ran about $300, Indy labor for all of the testing , clean-up and replacements was a great deal at another $300. He even threw in a free oil change for good measure. EuroTech in Natick, MA gets my kudo's here. 50 mile test run shows car running great.

jgt

Glad to hear you got it fixed quickly.
The labor for that job was very reasonable considering its a bit time consuming.
And I'm surprised the engine didn't hydrolock with all that oil. This was a very common issue in older X5's when their crankcase breather valves would freeze/fail and pull a few quarts of oil into the intake and engine.