Oil Separator Info / True solution.

[330]

This is very long but it will save you a lot of grief and big $$$. Many of us have seen it. Heavy smoke coming out the tail pipes, then so much smoke you think you’re on fire. I bought my X5 2001 4.4, that way because the previous owner thought they blew the engine and the dealer repair price was outrageous. I followed info from this forum and changed all the recommended parts, did it with a friend, $600 later I was fine.

Next winter (last month) it happened again. I opened the hood and saw oil all over the right side of the engine from top to bottom like and explosion. It was cold, single digits and happened after 15 minutes of driving. I was able to leave the car in a safe place and went to work. At noon I went back, it has warmed up and the heat of the engine helped. I checked the oil, it was down about two qts so I started it. Oil did not leak from the engine so I drove it home. Smoke continued to come out but less and less as I drove.

Degreased the engine at home and topped off the oil. Drove again with the dipstick slightly pulled out (I’ll explain later). At first my plan was to locate where the oil came out so I could replace that part only since we already did this job. Not a drop came from anywhere, then I drove to work, still full of oil as if nothing happened.

I looked at it real closely with a friend (BMW expert), all parts were functioning perfectly. We then ran several tests to determine root cause, here it is:

Most of this is known but I’ll go through it step by step

· Oil separator valve is needed to recirculate crankcase pressure back to the intake manifold and through the combustion chamber.
· Short trips do create moister in the oil and it can easily collect in the oil separator
· Single digit temps will cause the oil separator to freeze and stop the airflow to the intake manifold, crankcase begins to pressurize.
· Pressure builds in the crankcase and actually forces its way up into the combustion chamber, oil starts burning and tons of smoke will come out the back.
· Eventually the pressure will burst the weakest point.

In my case it came out of the oil filler cap. Oil was all over the washer fluid container, nothing on the 4.4 x5 engine is high enough to send oil where it did. Except the oil filler cap, the pressure was great enough to blow it right by the seal. Remember after I cleaned it, not a drop of oil came out from anywhere. Because the parts were new, valve cover gasket, oil separator and lines, they were able to withstand the pressure. The cap ended up being the weak point.

When you take it in at this point the dealer automatically changes all the parts associated with this failure. 9 times out of 10 it’s not needed. We actually created it again by blocking the oil separator and letting the pressure build up again. This time I had the cap on slightly loose so I wouldn’t do any damage and sure enough when the pressure reached a certain point it blasted out of the cap like a fire hose (sideways and down).

In the end I didn’t replace anything, I gave it an oil change and have been running for 4 weeks fine, it drives like new, I’m at 90K miles and it happened the first time at 84K. Although this could happen every time it gets cold, but when it thaws out the system may be just fine unless something burst.

The other thing we discovered and maybe most import is the dipstick seal. It’s a double Oring that will hold a fairly high pressure, sometimes it’s hard to pull it out by hand. If it gets real cold just pull it out and put it back with only one o ring in the tube, just don’t fully seat it. You will be able to see the top Oring sticking out of the dipstick tube. Make sure there isn’t any resistance when you pull it out, do it a few times. You now have created a pressure relief valve. If this happens again it will shoot your dipstick out and dump a bit of oil in that area. Not the best solution but mine is in this position because I don’t plan to do this job again.

Bottom line it’s a real crappy design but I feel a little better about it now that I know exactly whats going on. I may actually buy a smaller size oring for the dipstick so it’s sure to come out if the oil separator freezes.

[primetime]

I agree with what you're saying for the most part and in principle. However I'll have to dissagree with your method of pressure relief. I have to believe that BMW purposefully makes the dipstick double sealed for a reason. I understand that you are wanting to relieve pressure and you've found a method that works for you and seems to be working in general. However I for one, can not feel comfortable driving the vehicle if its not being driven in the condition that its supposed to be driven in. Meaning, the car better be doing what its supposed to be doing at all times. i don't feel comfortable driving with a dipstick not fully secured the way its supposed to be. I feel that the best method is to burn off condensation with longer drives whenever you can, and keep an eye on the seperator and VCG in the winter by checking for leaks, smoke, and goo under the oil cap.

I see that you are trying to offer up solutions for those who don't wish to deal with this headache and much of your information is accurate, especially the points of how the seperator fails..But in my opinion, in my own experience and knowledge its best to have the vehicle in the best working condition when you're driving it or going to be driving it. No special quirks, or not fully sealed dipsticks to relieve pressure or anything like that. Thats my 2 cents on it...

[330]

I understand but I'm not going to risk it again on a poor design. Sure I'll take all the precautions you’re talking about but taking it one step further will guarantee you won't damage anything. What is your concern about leaving the dipstick as I described on a super cold morning?

Looks like someone else just posted with the problem. If I didn't do all my own work I would never keep this car. And BMW charging so much to repair it when it may not need those parts is a sin. Just offering some options, I'm sure some of the people who paid $2000 to repair it only to happen again wish the dipstick pushed out and not half the engine. In my case I got lucky it was the oil cap. There you go a better solution would be a pressurized oil cap like the coolant system. Too much pressure and it's released through the cap. Anything is better the current design and I'm a die hard BMW fan, I have three of them now, wouldn't replace any of them

[amacman]

I thought also of a pressure dump valve in the oil filler cap as good solution to preventing engine damage by a frozen oil separator .
properly manufactured kit required ASAP .

[J.Belknap]

Originally Posted by primetime

I have to believe that BMW purposefully makes the dipstick double sealed for a reason.

Agreed, it's kind of hard for the intake manifold/oil separator to pull crankcase vacuum on a motor that isn't sealed.

But, if you just don't trust the oem oil/separator system, there's always a more complicated/expensive solution: Star Machine

Originally Posted by amacman

I thought also of a pressure dump valve in the oil filler cap as good solution to preventing engine damage by a frozen oil separator .
properly manufactured kit required ASAP .

Any manual boost controller will work as a failsafe.

[330]

You may have misunderstood me. If you have to drive when it's zero degrees out you may want to go up one O-ring on the dip stick. The engine is still sealed just gives it a place to release high pressure in case of the catastrophic OS failure. Like a donut tire when you get a flat, it's temporary so you can continue to go. You certainly don't want to use it all the time.

Remember the newer X5 has pressure relief on the valve cover, same concept.

Although I like the suggestion about a pop off valve on the oil cap. A second oil cap could be used, fitted with a valve and put on only in extremely cold weather.

Have you guys seen the service bulletin from BMW Service Engineering about the heat wrap for the vent system which connects to your battery? Here it is but without the pictures.

SI B11 01 04
Engine
March 2004
Service Engineering
SUBJECT
Heated Wrap for Crankcase Vent System
MODEL
E53 X5 with M62 engine from start of production through 9/2003.
SITUATION
During periods of driving in extreme cold weather conditions, certain X5 vehicles may experience misfiring, blue smoke from the exhaust, high oil consumption/oil loss or engine damage.
CAUSE
Condensation in the crankcase vent system could freeze, causing higher than normal crankcase pressures. In extreme cases, this could cause engine oil to be introduced into the intake manifold and then into the combustion chambers. Should sufficient oil quantities enter the cylinders, engine damage could result.
CORRECTION
Install a heated wrap kit around the crankcase vent hoses.

[msammy]

330,
Well, I have to say, this is one on the most well-thought and factual posts I've seen in quite some time!
By the way:

I often wondered why I've never had this problem. I have the moisture under the cap every winter, the glob on the stick when checking oil, and at 97K, it's never happened. Big reason must be it's a garaged vehicle and never gets any colder than about 40F in my garage even on the coldest nights. After work, even though it's below freezing, still not cold enough to freeze up since it's not as cold as late at night and I drive off fine. I like the dipstick thing as a stop-gap measure - saftey valve ready to blow off and save thousands of $$$'s. Next overnight trip that I take the X5 on, I will pull the dipstick out 1 ring as you suggested just to be on the safe-side. It's interesting that once the car thaws out (the OS), it runs normally like nothing ever happened once the oil burns-off of course. I certainly will not rush to the dealer if this happens to us, just be patient, let her warm-up and be on your way! Thanks for sharing this info with us!

[amacman]

Originally Posted by J.Belknap

Agreed, it's kind of hard for the intake manifold/oil separator to pull crankcase vacuum on a motor that isn't sealed.

But, if you just don't trust the oem oil/separator system, there's always a more complicated/expensive solution: Star Machine



Any manual boost controller will work as a failsafe.

I had my idea a while back with a view to finding valves for the correct pressure , I just never got around to doing anything yet .
someone recently posted info on the pressure parameters for various BMW engines . some as low as 0.2 bar , some up to 1 bar , so different valves required depending on engine .
do you have any info on manual boost controller .

[J.Belknap]

Originally Posted by amacman

I had my idea a while back with a view to finding valves for the correct pressure , I just never got around to doing anything yet .
someone recently posted info on the pressure parameters for various BMW engines . some as low as 0.2 bar , some up to 1 bar , so different valves required depending on engine .
do you have any info on manual boost controller .

It's just an adjustable bleed valve that can be built for $30 at the hardware store.

[330]

Thanks msammy. If this happens, I wouldn't let the car just sit a bit, you need it to let the OS completely thaw out, I waited 4 hours. Then make sure you have enough oil to start it. Tons of smoke will continue to come out until it burns off, oil will still be in the combustion chamber and continue to burn in the catalytic converters. While this is happening make sure no oil is leaking from any part of the engine. If it's leaking you burst something important, like OS, hoses or valve cover gasket. If no leaks you can drive it home, then lots of degreaser.

I work for a service engineering organization similar to the BMW Service Engineering group. We deal with these types of problems and make sure the new design doesn't have the same problem. Unfortunately most companies don't take care of the product after its released if a redesign is needed. Keep it in the garage and you’ll be fine.