E70 S63 - How to properly diagnose smoking at idle

[PhatP]

Hi Xbimmers,

Newer E70 X5M owner here looking for some thoughts on quick and simple ways to diagnose smoking at idle for the S63. I'm coming from an E39 M5 (S62) and a e53 4.8is (N62) so I've had some previous experience with smoking BMW V8s. 😂 I also know how expensive these M cars can be when you start throwing parts at a problem so I'm trying to attack this in a methodical way that hopefully helps other owners with the same issues.

Symptoms and observations from my truck:

-starting up after leaving it sit over night there is no initial smoke.
-no smoke at stop lights or accelerating unless it's been idling 5-10 mins
-after idling for 10 minutes there are obvious puffs of smoke out the back and if I rev it you can clearly see clouds of smoke
-oil consumption is 1l/1000km
-i have very sooty pipes
-no codes or other errors after scanning with ISTA
-no obvious performance issues with the engine. It seems to pull hard with no misfires.
-The other thing I noticed was the oil cap can easily be unscrewed at idle, there doesn't seem to be much vacuum and there was no change in engine running when I take it off either.... No stumbling, idle change etc.


Poking around the various forums everyone seems to jump right to stem seals because of the issues with the n62 and n63, but it appears there are a few other and maybe even more common causes for smoking that can be overlooked.

Stem seals - the common one people suggest first. Reading up it seems that because the s63 runs much cooler than the n63 bad stem seals are much less common. My truck has a history of oil changes every 3000 miles/5000km so I was leaning away from this one but I had stem seal issues on my 4.8is which greatly improved with Barrs oil seal conditioner. I used a bottle on the S63 and there was no difference in smoking after 1000km.

CCV/PCV - the next most obvious culprit is the CCV/PCV valve failing open and allowing oil vapor back into the cylinders where they are burnt.

Oil separators - from reading it seems that the oil separators might be the most overlooked item that directly causes oil consumption and smoking in the s63. Located inside the valve covers, they remove most of the oil so it doesn't get injested into the CCV/PCV return. If they fail (get clogged, and can't drain) you'll end up with a ton of oil vapor going back into the engine to be burned. I believe that in most cases where valve seals are done, the oil separators were changed by the dealers as well... So was the fix the valve seals or the fact that the oil separators were also changed when the valve seals were done?

Turbo oil return blockage - this one also seems to be pretty comon. The turbo oil return cokes up and blocks the oil return. Any oil then drains from the turbo outlet into the combustion chamber.

I've already added Barr's valve seal conditioner and there was no change so I'm going to put the stem seals aside for the moment as the cause.

Is there a good way anyone can suggest to confirm or deny if the PCV valve or oil separators are the issue? I was thinking of disconnecting the PCV lines and letting it idle and see if there's any smoke and if any oil drains from the PCV valve outlet. Not sure if this would work since it's the positive pressure from crankcase that is drawing in the oil vapor from the PCV system.


Thanks in advance for any thoughts!
Phat P

[XRatedM]

Originally Posted by PhatP

Hi Xbimmers,

Newer E70 X5M owner here looking for some thoughts on quick and simple ways to diagnose smoking at idle for the S63. I'm coming from an E39 M5 (S62) and a e53 4.8is (N62) so I've had some previous experience with smoking BMW V8s. 😂 I also know how expensive these M cars can be when you start throwing parts at a problem so I'm trying to attack this in a methodical way that hopefully helps other owners with the same issues.

Symptoms and observations from my truck:

-starting up after leaving it sit over night there is no initial smoke.
-no smoke at stop lights or accelerating unless it's been idling 5-10 mins
-after idling for 10 minutes there are obvious puffs of smoke out the back and if I rev it you can clearly see clouds of smoke
-oil consumption is 1l/1000km
-i have very sooty pipes
-no codes or other errors after scanning with ISTA
-no obvious performance issues with the engine. It seems to pull hard with no misfires.
-The other thing I noticed was the oil cap can easily be unscrewed at idle, there doesn't seem to be much vacuum and there was no change in engine running when I take it off either.... No stumbling, idle change etc.


Poking around the various forums everyone seems to jump right to stem seals because of the issues with the n62 and n63, but it appears there are a few other and maybe even more common causes for smoking that can be overlooked.

Stem seals - the common one people suggest first. Reading up it seems that because the s63 runs much cooler than the n63 bad stem seals are much less common. My truck has a [...]

If there's no smoke at cold start, then most likely it's the PCV valves/system.

[SlowX6M]

On my n63 I used to have very occasional puffs of smoke that I would observe maybe once a month or two, before and after the whole valve stem job with the new turbo oil and coolant lines, etc. It was something that would happen very rarely, and go away after running the car for an hour or so. Usually it would happen if the car was ran hard and hot, and then sat idling, so almost like somehow oil got pulled into the intake/combustion chamber, and then took a little while to burn off.

Replaced the CCV lines about 2 years and 15k miles ago, and have not observed anything since. The car still consumes 1 liter of oil every 1200-1500 miles, which is relatively normal.

That being said, I am not sure it was the CCV, my mechanic inspected the old CCV lines and said they were fine, but I brought him the new parts and insisted he replace them anyway. It it were indeed the CCV line that were causing it, I guess they were starting to fail and perhaps occasionally allow some oil to get pulled into the intake.

Either way, the CCV is the easiest and the cheapest possible culprit to address. You're looking at about $250 in parts + $200-300 labor, and it's worth a try if it resolves the issue. Everything else you're looking at major $ - the dealer covered my valve seals job under the lawsuit, otherwise they said its a $12k job in 2019 money, probably way more today. While they were at it they also did the turbo oil/coolant lines, and some other stuff, and only charged me about $2k for the parts, no labor. If I was to pay for everything out of pocket, I would just get a new engine.

[slovakE70]

Originally Posted by PhatP

Hi Xbimmers,

Newer E70 X5M owner here looking for some thoughts on quick and simple ways to diagnose smoking at idle for the S63. I'm coming from an E39 M5 (S62) and a e53 4.8is (N62) so I've had some previous experience with smoking BMW V8s. 😂 I also know how expensive these M cars can be when you start throwing parts at a problem so I'm trying to attack this in a methodical way that hopefully helps other owners with the same issues.

Symptoms and observations from my truck:

-starting up after leaving it sit over night there is no initial smoke.
-no smoke at stop lights or accelerating unless it's been idling 5-10 mins
-after idling for 10 minutes there are obvious puffs of smoke out the back and if I rev it you can clearly see clouds of smoke
-oil consumption is 1l/1000km
-i have very sooty pipes
-no codes or other errors after scanning with ISTA
-no obvious performance issues with the engine. It seems to pull hard with no misfires.
-The other thing I noticed was the oil cap can easily be unscrewed at idle, there doesn't seem to be much vacuum and there was no change in engine running when I take it off either.... No stumbling, idle change etc.


Phat P

I've got E70 with N63 engine (50i) and had exactly the same symptoms as you described : no smoke on start up nor full throttle, only smoking after 10 min idle when I smashed the throttle, oil consumption around 1l/1000 km.
In my case the reason for smoking and partly oil consumption was bad valve stem seals. The seals were hard and not really sealing around the valve stem anymore.
I've tried everything I could: oil additives, "thicker oil", replaced PCV valves - nothing helped. After valve seals replacement no more smoke and oil consumption improved to 1l every 4000 km.
Note that I'm doing a lot of short trips, maybe that's the reason for bit of oil burning and also have oil leak which appears to be turbo return cover.

However, recently noticed same thing as you described - very little vacuum when opening the oil cap while engine running. I remember after PCV replacemet there was noticeably more vacuum inside the engine. Could this mean that PCVs are bad again ? Last time I changed them was 2.5 years ago .... Also noticed little bit more oil consumed since last top up.

[Sophisticated Redneck]

Originally Posted by PhatP

Hi Xbimmers,

Newer E70 X5M owner here looking for some thoughts on quick and simple ways to diagnose smoking at idle for the S63. I'm coming from an E39 M5 (S62) and a e53 4.8is (N62) so I've had some previous experience with smoking BMW V8s. �� I also know how expensive these M cars can be when you start throwing parts at a problem so I'm trying to attack this in a methodical way that hopefully helps other owners with the same issues.

Symptoms and observations from my truck:

-starting up after leaving it sit over night there is no initial smoke.
-no smoke at stop lights or accelerating unless it's been idling 5-10 mins
-after idling for 10 minutes there are obvious puffs of smoke out the back and if I rev it you can clearly see clouds of smoke
-oil consumption is 1l/1000km
-i have very sooty pipes
-no codes or other errors after scanning with ISTA
-no obvious performance issues with the engine. It seems to pull hard with no misfires.
-The other thing I noticed was the oil cap can easily be unscrewed at idle, there doesn't seem to be much vacuum and there was no change in engine running when I take it off either.... No stumbling, idle change etc.


Poking around the various forums everyone seems to jump right to stem seals because of the issues with the n62 and n63, but it appears there are a few other and maybe even more common causes for smoking that can be overlooked.

Stem seals - the common one people suggest first. Reading up it seems that because the s63 runs much cooler than the n63 bad stem seals are much less common. My truck has a history of oil changes every 3000 miles/5000km so I was leaning away from this one but I had stem seal issues on my 4.8is which greatly improved with Barrs oil seal conditioner. I used a bottle on the S63 and there was no difference in smoking after 1000km.

CCV/PCV - the next most obvious culprit is the CCV/PCV valve failing open and allowing oil vapor back into the cylinders where they are burnt.

Oil separators - from reading it seems that the oil separators might be the most overlooked item that directly causes oil consumption and smoking in the s63. Located inside the valve covers, they remove most of the oil so it doesn't get injested into the CCV/PCV return. If they fail (get clogged, and can't drain) you'll end up with a ton of oil vapor going back into the engine to be burned. I believe that in most cases where valve seals are done, the oil separators were changed by the dealers as well... So was the fix the valve seals or the fact that the oil separators were also changed when the valve seals were done?

Turbo oil return blockage - this one also seems to be pretty comon. The turbo oil return cokes up and blocks the oil return. Any oil then drains from the turbo outlet into the combustion chamber.

I've already added Barr's valve seal conditioner and there was no change so I'm going to put the stem seals aside for the moment as the cause.

Is there a good way anyone can suggest to confirm or deny if the PCV valve or oil separators are the issue? I was thinking of disconnecting the PCV lines and letting it idle and see if there's any smoke and if any oil drains from the PCV valve outlet. Not sure if this would work since it's the positive pressure from crankcase that is drawing in the oil vapor from the PCV system.


Thanks in advance for any thoughts!
Phat P

You can add catch cans + adjustable vacuum valves as I did in various writeups to increase the Crankcase vacuum which will in-turn reduce the amount of oil sucked past the valve stem seals. At idle your engine will be pulling approx -20 psi vacuum inside the cylinders, stock BMW Crankcase pressure is less then -1psi. You can adjust it to around -10 psi in the crankcase so there will only be about a 10 psi differential at idle instead of nearly 20 psi differential stock and much less oil will work its way past the valve stem seals. It will buy you some time.

Ultimately though when it gets bad enough, you will need to do the valve stem seals. After I did mine I now only burn 1 liter every 5000 miles and that with 185k on the clock now (did the seals at 138k miles).

[TonyBologna]

Ever figure out what the problem was? I’m having similar symptoms.