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White smoke comming out of engine bay

8K views 8 replies 4 participants last post by  kc740i 
#1 ·
(1995 740i)

I honestly have no idea what is going on with this smoke in my engine bay if anyone can provide any suggestions. As far as i know this problem does not seem to affect the performance of the car, however it is quite embarrasing to drive around in a smoking bmw =/. I have a few photos that may help to diagnose the problem.

When i start the car up and let it idle, there is no smoke, but when i start driving around, the smoke starts to pour out from the area marked with arrows on the photos. I am not completely sure, but it does smell somewhat like burning oil. I pulled off the panel covering my ignition coils and spark plugs to make sure the smoke wasnt comming from that compartment. I found a small oil leak one of the cylinders (the one farthest to the back ont he left side(closest to the winshield). The smoke appears to be comming from under the block from what i saw. Also the oil cap is leaking. Is there an O-ring that is supposed to be on the bottom of the oil cap, or is it supposed to seal w/o one? If anyone has any suggestions / any ideas to further diagnose the problem, anything would be greatly appreciated
 

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#2 ·
Looks like you have a very bad oil leak which is getting on the exhaust manifold and that is what is causing the smoke. The oil cap definitely should have a flat rubber seal on the bottom of it where it seals against the valve cover. By the looks of the picture the cap is not sealing and that is causing a major leak. Luckily that would be an easy fix, just buy a new oil cap and clean the area as best as possible.
DT
 
#5 ·
All you need to do is buy a new oil filler cap (prob $10 or less at the dealer) and then buy a can of brake cleaner and with the engine cold and not running clean all of the oil residue and then after that rinse the area down with water. (be careful not to get the water into any electronics or down the spark plug bores) After you replace the oil filler cap, drive the car for a few days, see if it fixes any of the running problems. BMW runs a sealed crankcase so a large oil leak is also a vacuum leak which will cause some issues. Good luck.
DT

P.S I dont recommend the driving off the cliff method but if you decide to do that please record it and post it in the video forum :)
 
#7 ·
The same problem I have on my 93 740i M60!

I was told the Crank Case Pressure is too high and it is Blowing the oil out of the least resistance places it can find.
I too am having the Oil leak around the Filler Cap and the Right side of the Engine.Nothing while Sitting still but when I drive it is so Embarassing to be seen in this car.
So you need to check the PCV Valve unit and that should fix it, So I am told.
I have not yet tackled it myself, But I am going to have to very soon!

Good Luck!

Robert,:driving :bimmer
Houston, Texas
 
#8 ·
perhaps the passenger side valve cover gasket is where the leak is coming from, it doesn't take much of a leak to create a HUGE mess (and smoke). The crankcase vent valve on the V8's are a MF'r if you are not moderately inclined to turn wrenches. The valve is actually the plate that is bolted to the back of the intake manifold. You have to remove the intake manifold to replace the vent valve although I can replace one without removing the intake, but I only do that if my customer won't buck up the extra cash to do the whole intake. Buy yourself a new intake reseal kit. It has the throttle body gasket, intake gaskets, vent valve and the gasket for it and new bolts. But like I said, this is a VERY complex and difficult task that should really be left to a well trained technician or a do it yourselfer with good skills. If you do decide to do it.. go to church before starting, prepare to scar up your hands and arms, have a spare car (it will take you a long time) and go to church again when you're done. You'll know why I say go to church after you count the number of F bombs and 4 letter swear words you scream as you throw wrenches at your mad wife's cat. :mad:

Happy Wrenching !! :D
 
#9 · (Edited)
eww that was a nasty problem that was hard to find. I got it all fixxed, turns out there was a hairline crack right under the oil cap that was causeing oil to drip out and run down pipes onto the exhaust manifold. a little welding fixed this problem. The other problem was the valve cover gaskets, they were leaking oil profusely, which had also caused my spark plugs to foul out (oh yay!!). My crankshaft seal still needs to be replaced, but the oil drip is so small, you would spend 2 days trying to gather a tablespoon of oil.

Robo i would seriously suggest replacing the cap and having the threading and such checked for any cracks at all, as it was a problem that was not easily recognized.

Just to give you an idea of my costs , 300 for full valve cover gasket install (i was going to do it but i dont like being responsible for screwing up my engine if i applied the silicone incorrectly to the gaskets) + $40 for new spark plugs. i had some other stuff done including power steering hose, ac belts and ac housing(it was cracked). for a grand total of $700(ouch!!). I found out what BMW stands for ~ BMW = bring money withya.

Well anyhow problem fixed and broke again.... the BMW saga continues

Thanks for the help everyone!!!
 
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