2005 X5 4.4i exhaust smoke
 

I have a 2005 BMW X5 4.4i that recently started smoking at idle. It recently passed inspection and all systems seem to be fine. No lose of power or engine lights. At idle the car smokes a little and then when I step on the gas after being at a light it smokes briefly then stops. Actually the car is running great right now. Any ideas what could be the problem?

any feedback would be greatly appreciated.

Depending on the color of smoke and if your X uses oil, that sounds like valve stem seals to me

Before I had mine replaced around 84k miles, I would sit at a stop light or in a drive through and there would be a little whitish-blue smoke. Then when I'd accelerate away from the stop, I'd leave a nice big cloud behind me.

In terms of repair, you can try using heavier oil or a stop leak additive to band-aid the problem and periodically add oil. But the root cause won't be fixed until you replace those valve stem seals (also called valve guide seals). Basically, there are little rubber seals around each valve stem and oil is getting past them because they're failing.

The repair is pretty expensive. There's a tool made by a company called "AGA" which lowers the cost but expect to pay $1500 - $2500 depending on the shop. The job takes about 15-20 hours and the parts are relatively inexpensive.

Without the tool, you have to pull the heads which is even more expensive. I was quoted about $5000 - $7500 for that level of service. If you go this route, the mechanic can clean some ports inside the head and also replace the head gaskets while they're in there, which might be worth the extra expense to some.

Also, for what it's worth, my extended warranty (United Car Car) covered the repair. After the repair, my X seems a little more peppy, so I think it's worth doing. Plus burning oil can be hard on your emissions control components and make them wear out sooner.

Here's a thread with my experience: http://www.xoutpost.com/bmw-sav-foru...t-surgery.html

It could be a clogged EGR valve on the back of the intake referred to as Crank Case Vent CCV. They go bad, I replaced 2 in two years for different reasons.

Yes, it could be the CCV too. I had mine replaced in hopes it was the cause of my smoking 4.4i. It wasn't too expensive; something like $200.

This is all great advise! With no apparent loss of power is this more likely to be the CCV? I drive on average of 6K miles per year so spending 2K - 5K does not seem worth it. I appreciate all the help. On another note the coolant level warning came on today and I just added coolant 3 weeks ago. Thoughts?

The valley pan gasket usally goes....see if have slight antifreeze dripping on the back of the engine or trans. The entire intake and valve cover has to come off. Also the coolest tank overflow all go bad and leak.
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Generally the 4.4 don't suffer from valve seals.

Losing coolant and smoke might be connected. Coolant smoke is white, oil smoke somewhat blue and fuel smoke is black. Coolant smoke has a sweet smell, entirely different than oil or fuel smoke. If you are not familiar with the difference drop a drip of oil on the exhaust manifold. Fuel smoke smells like fuel.

If the smoke doesn't smell like coolant, I would take a flashlight with a narrow beam so you focus only where the beam is and check all hoses radiator, expansion tank, water pump for coolant residue. Do you notice any coolant on the ground a half hour or so after you have driven it enough to get the coolant up to operating temp? There are also coolant hoses at the back of the engine that are easiest to see with the engine cover removed.

UPDATE:

Added coolant today and when I got home I checked for leaks. It is dripping coolant one drip every second. I looked and it seems to be coming from the tank but I can't full see where. Any suggestions? This seems like it would be a job that I can fix myself.

By tank you mean the expansion tank? Can't find where it is wet with your hand after it cools down?