[N111CUK]

Hi all.

now this isn't chronic I get about 1500miles per qt of oil. and I also drive the car fairly hard.

so i have white smoke from the exhaust only when coming to a stop after boost.
Once idling the smoke stops. It smells like burnt oil.
If a rev the engine in nuteral only a tiny bit of white smoke but hardly noticeable.
I do have a catless exhaust into one back box.*

Have tried the following.*

1. Delete the occ (oil catch can). No change*

RB has suggested I swap the valve cover for a new unit. He thinks the crank case and pcv systems are not breathing right. I will be doing this next week. I'll also be doing a leak down test for good measure but at 530bhp I'm sure my compression is good.

Valve stem seals? My logic is they must*be OK because it only smokes after boost has been met. If the seals had failed I should see white smoke in all conditions?

I might remove the downpipes to inspect the turbines for any play. These are new rb turbos and I would be shocked if they had failed already. 3k miles so far.*

I have another theory but I am no expert

Less exhaust pressure might create a pressure difference in the turbo meaning when the boost is on the pressure on the cold side is greater than the hot side forcing oil in the bearing house to flow out of the path of least resistance. Would that be true? If so creating exhaust back pressure could help.

Thanks for the support*

Adam*

[u2b]https://youtu.be/lRQSGLlXHGY[/u2b]

[bigdnno98]

Are you completely catless? How bad does it smoke? I'd def check out the PCV system. You can do a leak down for piece of mind. Did it smoke before turbo install? Do you replace oil feed lines?

[N111CUK]

yes completely catless

I noticed the smoke more once catless exhaust system went on.

[mankytron]

Valve stem seals generally show under vacuum conditions...so if you floor it to full boost say in 3rd gear then let off and let it coast down in gear the engine creates a strong vacuum and sucks oil past valve stem seals, when you stop and idle the car will usually show oil burning smoke then clear up. Stem seals are just like any other gasket, over time with extreme under hood heat they get hard and will not seal.

[WedgePerformance]

If you're running the RB PCV or if you haven't replaced your PCV do so. This isn't the first time I've seen this. I had another customer with the same issue and he replaced his RB PCV with a good PCV and the white smoke went away. I'm not saying all RB PCVs are bad, I'm just saying this isn't the first PCV I have seen go bad and cause the white smoke.

[N111CUK]

thanks wedge I could install the new oem pcv which came with the valve cover as a test.

[fazman]

Originally Posted by mankytron

Valve stem seals generally show under vacuum conditions...so if you floor it to full boost say in 3rd gear then let off and let it coast down in gear the engine creates a strong vacuum and sucks oil past valve stem seals, when you stop and idle the car will usually show oil burning smoke then clear up. Stem seals are just like any other gasket, over time with extreme under hood heat they get hard and will not seal.

Has someone done a valve stem seal DIY? or is this a case to run seafoam in the motor oil or do a motor flush?

[N111CUK]

Originally Posted by mankytron

Valve stem seals generally show under vacuum conditions...so if you floor it to full boost say in 3rd gear then let off and let it coast down in gear the engine creates a strong vacuum and sucks oil past valve stem seals, when you stop and idle the car will usually show oil burning smoke then clear up. Stem seals are just like any other gasket, over time with extreme under hood heat they get hard and will not seal.

would it not create vacuum when revving the engine in nuteral?

[N111CUK]

Originally Posted by bigdnno98

Are you completely catless? How bad does it smoke? I'd def check out the PCV system. You can do a leak down for piece of mind. Did it smoke before turbo install? Do you replace oil feed lines?

yes completely catless

new valve cover is waiting for install

rb install was done with all new hardware.

I noticed the smoke once I installed the catless exhaust.

I understand a little smoke might be the side effects of no cats but want to eliminate it as much as possible

[MM Performance]

First thing I would do before going off to spend a bunch of money replacing parts not knowing what will do the trick is take off the downpipes and inspect the turbines to see if there is any evidence of oil leaking past the turbine seals. That's the quick and easy inspection. For a more full proof and detailed inspection of the turbines, I would remove the turbine housing and check under the turbine heat shield if there is any evidence of leak, this is ALOT more labor intensive though because it would basically be like removing the turbos. If no leaks are verified, I would start doing what your currently doing, otherwise you may be chasing a rabbit in circles.

Also does smoke come out both your pipes or one pipe or even one more than the other? If one pipe, this could be more of an indication that it could be turbo seal related as opposed to a general system issue like PCV/CCV.

[whosdady]

Originally Posted by MM Performance

First thing I would do before going off to spend a bunch of money replacing parts not knowing what will do the trick is take off the downpipes and inspect the turbines to see if there is any evidence of oil leaking past the turbine seals. That's the quick and easy inspection. For a more full proof and detailed inspection of the turbines, I would remove the turbine housing and check under the turbine heat shield if there is any evidence of leak, this is ALOT more labor intensive though because it would basically be like removing the turbos. If no leaks are verified, I would start doing what your currently doing, otherwise you may be chasing a rabbit in circles.

Also does smoke come out both your pipes or one pipe or even one more than the other? If one pipe, this could be more of an indication that it could be turbo seal related as opposed to a general system issue like PCV/CCV.

+1 This is what you need to do to start ruling things out. If you remove the dp's and see oil in the housing, it's the turbo seals. However, the way yours smokes sounds like something different to me. But everyone's smoking issue is a little different. The oldest n54's are now 9 years old. After years of abuse it could be anything...

[mankytron]

Originally Posted by N111CUK

would it not create vacuum when revving the engine in nuteral?

Sure a little bit, as long as the engine is still turning over fast and the throttle plate is closed, but not like running up to redline and letting it slow down gradually leaving it in gear...with the throttle closed. I would def check simple first, like others have said. Pcv valve and hose, and visual on turbos with dp off.

[mankytron]

Originally Posted by fazman

Has someone done a valve stem seal DIY? or is this a case to run seafoam in the motor oil or do a motor flush?

I have never seen a diy on valve stem seals, it would be fairly involved. In some engines it can be done under hood without pulling the head. Cams come out, compressed air in cylinder to hold valves up, and valve train disassembled to pull old seal and install new seal. On high mile engine valve guides could be worn also causing oil burning. I am not sure if the n54 has replaceable guides or not.

Seafoam or motor flush may help with stuck gummed up rings, but likely due nothing to hard leaky valve stem seals.

[N111CUK]

Originally Posted by MM Performance

First thing I would do before going off to spend a bunch of money replacing parts not knowing what will do the trick is take off the downpipes and inspect the turbines to see if there is any evidence of oil leaking past the turbine seals. That's the quick and easy inspection. For a more full proof and detailed inspection of the turbines, I would remove the turbine housing and check under the turbine heat shield if there is any evidence of leak, this is ALOT more labor intensive though because it would basically be like removing the turbos. If no leaks are verified, I would start doing what your currently doing, otherwise you may be chasing a rabbit in circles.

Also does smoke come out both your pipes or one pipe or even one more than the other? If one pipe, this could be more of an indication that it could be turbo seal related as opposed to a general system issue like PCV/CCV.

I've booked a ramp in a weeks time to get under it and remove the downpipes.

your absolutely right it's best to rule out the turbos early on.

I bought the valve cover in the event I need it during my time ripping into it. I'll try a new oem pcv valve first as this is a 10min job. if the cover isn't needed I'll get a refund.

if the turbos are OK then it's on with the new valve cover.

fingers crossed that it's simple

[N111CUK]

Originally Posted by mankytron

Sure a little bit, as long as the engine is still turning over fast and the throttle plate is closed, but not like running up to redline and letting it slow down gradually leaving it in gear...with the throttle closed. I would def check simple first, like others have said. Pcv valve and hose, and visual on turbos with dp off.

I could test the theory by driving it then put it in nuteral whilst applying breaks I'll keep the throttle open by blipping the throttle

[bigdnno98]

Many n54s smoke a little when completely catless. That's why most people keep the secondary cats in. Not sure where the smoke comes from. My last 335i smoked a little after completely catless with only 40k miles on it and stock turbos.

[bigdnno98]

Slap a go pro on the rear of the car. Go for a drive and post vids.

[N111CUK]

Originally Posted by MM Performance

First thing I would do before going off to spend a bunch of money replacing parts not knowing what will do the trick is take off the downpipes and inspect the turbines to see if there is any evidence of oil leaking past the turbine seals. That's the quick and easy inspection. For a more full proof and detailed inspection of the turbines, I would remove the turbine housing and check under the turbine heat shield if there is any evidence of leak, this is ALOT more labor intensive though because it would basically be like removing the turbos. If no leaks are verified, I would start doing what your currently doing, otherwise you may be chasing a rabbit in circles.

Also does smoke come out both your pipes or one pipe or even one more than the other? If one pipe, this could be more of an indication that it could be turbo seal related as opposed to a general system issue like PCV/CCV.

could I not use a borescope to get a look at the turbines.

Maybe via the post cat lambda sensor bung. I have catless downpipes of course

[MM Performance]

Originally Posted by bigdnno98

Many n54s smoke a little when completely catless. That's why most people keep the secondary cats in. Not sure where the smoke comes from. My last 335i smoked a little after completely catless with only 40k miles on it and stock turbos.

Don't mistake steam with smoke. I'm fully catless and running straight e85. This combo produces quite a bit of steam, byproduct of e85 combustion.

[N111CUK]

Originally Posted by bigdnno98

Many n54s smoke a little when completely catless. That's why most people keep the secondary cats in. Not sure where the smoke comes from. My last 335i smoked a little after completely catless with only 40k miles on it and stock turbos.

what do you think about my theory in OP where exhaust pressure might effect bearing seals.

[N111CUK]

Originally Posted by bigdnno98

Slap a go pro on the rear of the car. Go for a drive and post vids.

I don't have a go pro. I'll try and improvise something else.

[N111CUK]

Originally Posted by MM Performance

Don't mistake steam with smoke. I'm fully catless and running straight e85. This combo produces quite a bit of steam, byproduct of e85 combustion.

I'm pump and 100% meth. it's also stinky and lingers in the air.

on idle I do have some steam but this vanishes in the air so I'm sure which is which.

I'll try and get video footage