White Smoke, Cold weather, Oil Separator Reminder!

330 · #1 12-23-2010, 12:02 PM

It’s that time of year when temps will go into single digits and the built up water condensation in your oil will freeze in the oil separator. Most of us have had it or heard about it. Car starts fine runs great for about 15 minutes then the dreaded white smoke begins to appear as the pressure continues to build because the oil separator has more water in it than oil. Those sort trips will do it every time and if you park outside in single digit weather you will definitely get this problem.

The built up pressure will eventually blow out something, OS or hose or if you’re lucky oil will blast out the oil cap seal.

My plan for this year is to change my oil just before the single digit temps arrive (late December). On those extremely cold nights I may garage it if I decide to pull out one of the nicer cars. If I leave it out then a 10 minute warm up 1 hour before I leave will guarantee the temp inside the oil separator will go above freezing and melt and condensation that would cause blockage. The key here would be to let the engine sit off after it was started for 10 minutes. As a last precaution I pull the dip stick and only let one of the two “O” rings seal when I put it back in. If pressure builds it will force oil out of the dipstick. Big effort but if you have had the white smoke come out and then damaged your OS you know it’s worth it. Usually oil separators don’t fail on their own they get frozen and blocked, the pressure does the rest.

The X5 is like dating a super model………high maintenance. Good Luck.

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JCL · #2 12-23-2010, 12:34 PM

Good reminder at this time of year.

We should separate the two issues of the creation of condensation, and the freezing of the condensate in the oil separator. An owner could have lots of condensate in the oil separator, but have no problems until it is freezing outside.

Changing the oil won't do anything for the condensate in the oil separator, that has to be cleaned out independently if it has built up. Changing the oil can help to get rid of the condensate in the engine, that cream-coloured paste under the oil filler cap, and that is a good thing in and of itself. But if it has built up there, it is probably in the oil separator as well.

The most common thing to blow out if the oil separator freezes closed is a valve cover gasket. On the other hand, if it freezes open the engine can draw in liquid to the intake manifold. Not common, but possible, and a risk of hydraulic lock for the engine.

Also, idling an engine to warm it up for 10 minutes is not a good idea IMO. Start it, and drive it gently right away. Engines wear much more during warm up, and warming it by idling it just extends the warm up time. You want to get through that warm up period as quickly as possible, and driving it with load on it does that.

330 · #3 12-23-2010, 12:42 PM

Won't fresh oil with no water in it flush out some condensation in the OS? You have to change it anyway so it won't hurt.

My method to thaw out the OS will only be used a few days out of the year. How much engine wear will that be?? Starting up and driving is the correct thing to do but at 0 deg or less your certain to have a blocked OS if you do short trips. I've had this happen every winter, and learned my lesson. I guess another alternative would be to stay home or if you're really concerned about the engine wear at start up you can drive five minutes to a coffee shop and sit for 30 minutes or so. Both beat seeing white smoke and an engine covered in oil.

JCL · #4 12-23-2010, 12:49 PM

The separator isn't part of an oil flow circuit, so it won't be cleaned out by fresh oil. It just catches vapours from the crankcase (like a PCV system), and the vapours have moisture in them.

I understand where you are coming from with the warm-up plan, trying to ensure that any problem happens in the driveway instead of on the road. The right thing to do is to clean out the oil separator, everything else is just dealing with the symptoms of that problem.

The trick would be to put enough head into the engine compartment to melt any blockage, while not running it long enough to spew oil out if there is in fact a blockage. Cars have spewed oil out while parked in driveways, and I think it is better to be in the vehicle than leaving it unattended. All that said, if there is a risk of it happening from past driving practices (short trips, etc) then the real fix is just to clean it out.

1stE53 · #5 12-23-2010, 11:09 PM

Quote:

Originally Posted by JCL

The separator isn't part of an oil flow circuit, so it won't be cleaned out by fresh oil. It just catches vapours from the crankcase (like a PCV system), and the vapours have moisture in them.

I understand where you are coming from with the warm-up plan, trying to ensure that any problem happens in the driveway instead of on the road. The right thing to do is to clean out the oil separator, everything else is just dealing with the symptoms of that problem.

The trick would be to put enough head into the engine compartment to melt any blockage, while not running it long enough to spew oil out if there is in fact a blockage. Cars have spewed oil out while parked in driveways, and I think it is better to be in the vehicle than leaving it unattended. All that said, if there is a risk of it happening from past driving practices (short trips, etc) then the real fix is just to clean it out.

So you can simply clean the separator valve? difficulty level? I take my wife's X at least once a week (it is truly a fight to get that X away from her, even though she gets an E class in exchange

) to work, 40 miles each way. Still don't think it is far enough though to get engine hot enough to clean that crap out. How far do you suggest in Missouri winter weather? It has been as cold as -17C and is staying around -3 to 3 deg C lately.

JCL · #6 12-24-2010, 02:15 AM

40 miles will get it hot. You need to get some regular drives in (like your once per week) that get it hot enough to boil off the condensation, and that takes a little while.

If you look under the oil fill cap and see the cream-coloured paste, then you know condensation has built up, and formed that emulsification. If it is visible under the oil filler cap, it will be in the oil separator valve, and the lines to it, as well. Getting it hot won't get the paste out of the valve, once it is there.

Depends on which model engine, and which year, but BMW sold a kit to overhaul the oil separator valve, with a new diaphragm in it. By the time you get down to taking it all off, and replacing any lines that are soft, you have done all of the work to change it, it is the same amount of labour.

There are DIYs posted on changing the OSV, for various models. It isn't very difficult, but there are some tight spaces and lines that are hard to get to.

romeokc10 · #7 12-24-2010, 02:25 AM

Good post, it's shame some of us are terrified to drive our X5s in cold weather.

ashrafkh · #8 12-24-2010, 02:09 PM

i have the ssame problem-still to take it for the shop to fix it- but conclusion is that Oil seperator can be the reason for old engines M62, but for N62 its more seriouse

1stE53 · #9 12-24-2010, 02:18 PM

Quote:

Originally Posted by romeokc10

Good post, it's shame some of us are terrified to drive our X5s in cold weather.

Last winter I was nervous about it, this year not so much. Now that I understand the issue a lot more, I can do things to help prevent it. I spoke with someone who has a ford f150, his oil does the same thing.

amacman · #10 12-24-2010, 07:28 PM

cold is only an issue if the moisture is in the system
the moisture gets there in humid / maritime climate . usually around 0 Celsius .
air at minus 10 Celsius will not have moisture in it .
keep checking the oil filler cap for creamy gunge and if you see any this means you need to warm the engine properly .

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