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      09-07-2022, 01:08 AM   #1
JohnelP
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(N63) Oil Leak at Diverter Valve - Passenger side only

Hi,

Last year I have rebuilt my N63. I have noticed there is a oil leak at the passenger side diverter valve. Before tearing the engine apart, I did not notice any leak there. When I had the engine apart, I took the turbos out as a whole, without touching the diverter valve. I have seen the PCV hoses to have oil in them, and also there is some oil in the air duct of the air inlet of the turbocharger, but that was there before. but never to the point where diverter valve leaks oil. I tried to see if there is any oil leak inside the turbocharger from the oil lubrication channels. Other thing in my mind is the oil separator from the cyl head cover. But I see that to be fairly simple so i do not see anything can go wrong with that.

Or is it too much pressure in the engine and pushes air with oil mixture too fast for the separation to take place?
I recall I have seen it once, what pressure should I measure inside the crankcase? Assume some vacuum may be there due to PCV system? Or the blow by pressure is too strong, and i may see pressure in the engine??? Don't know... Throw the topic to see what other opinions are there
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      09-08-2022, 08:56 AM   #2
Sophisticated Redneck
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Quote:
Originally Posted by JohnelP View Post
Hi,

Last year I have rebuilt my N63. I have noticed there is a oil leak at the passenger side diverter valve. Before tearing the engine apart, I did not notice any leak there. When I had the engine apart, I took the turbos out as a whole, without touching the diverter valve. I have seen the PCV hoses to have oil in them, and also there is some oil in the air duct of the air inlet of the turbocharger, but that was there before. but never to the point where diverter valve leaks oil. I tried to see if there is any oil leak inside the turbocharger from the oil lubrication channels. Other thing in my mind is the oil separator from the cyl head cover. But I see that to be fairly simple so i do not see anything can go wrong with that.

Or is it too much pressure in the engine and pushes air with oil mixture too fast for the separation to take place?
I recall I have seen it once, what pressure should I measure inside the crankcase? Assume some vacuum may be there due to PCV system? Or the blow by pressure is too strong and i may see pressure in the engine??? Don't know... Throw the topic to see what other opinions are there
You are on the right path. I am assuming when you rebuilt your engine, you checked the turbo oil return lines to ensure they were not clogged as that is number on reason for oil coming out the diverter valves. To much crankcase pressure is second followed by bad turbo seals. I would replace your uppper CCV lines as there is an internal check valve that can fail or go all out and incorporate catch-cans. If still issues persist, turbo seals would be next suspect however with bad turbo seals you typically burn 1+ quarts of oil every 500 miles with constant smoke filled exhaust.
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      09-12-2022, 03:01 PM   #3
JohnelP
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Thanks
dealer claims they changed the turbo oil return tubes when they performed the ccp valve stem seals <10k miles ago. I trusted them; so, (maybe i made a mistake) i did not check them....

i see the crank ventilation valves are trivial flap type check valve towards the air inlet to the turbo. I could not see the pcv mechanism towards intake manifold, but i doubt it is fancy stuff.

I just got the vacuum/boost gauge, and i will check the crank pressure. i see from other's shared experience that the crank pressure varies a lot during different engine running conditions. i'll see where my engine stands; however if the crank pressure would be an issue, then driver side diverter valve should have oil, not only the passenger side.

though i think i may end up with two catch cans on both sides, and see if they collect same amount of oil..
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      09-12-2022, 06:44 PM   #4
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Quote:
Originally Posted by JohnelP View Post
Thanks
dealer claims they changed the turbo oil return tubes when they performed the ccp valve stem seals <10k miles ago. I trusted them; so, (maybe i made a mistake) i did not check them....

i see the crank ventilation valves are trivial flap type check valve towards the air inlet to the turbo. I could not see the pcv mechanism towards intake manifold, but i doubt it is fancy stuff.

I just got the vacuum/boost gauge, and i will check the crank pressure. i see from other's shared experience that the crank pressure varies a lot during different engine running conditions. i'll see where my engine stands; however if the crank pressure would be an issue, then driver side diverter valve should have oil, not only the passenger side.

though i think i may end up with two catch cans on both sides, and see if they collect same amount of oil..
Ya it looks that way but its actually the one of most complex CCV system BMW has ever designed. Embedded in T connection that goes to the lower CCV tubes is a special 2-way check valve that limits CC pressure at idle & part throttle non-boost conditions to about -1 psi, then under boost this valve shuts and redirects all CCV gases to the upper intakes/turbo inlets via the one-way check valve flaps that open and take over. Adding catch-cans is highly recommended as the oil/air separators in the valve covers are a joke. You will be shocked how much oil they catch (choose catch cans with sintered bronze 50 micron filters)

I did a deep dive on all of this years ago, if you search for catch cans on this forum you will find a ton of posts over the years from me and other members about addressing this issue along with going hard-core and adding your own adjustable one-way valves to increase CC vacuum past the paltry -1psi bmw has it set to. I run mine at -10ish psi. No more oil leaks from the rear main or anywhere else now for the past near 90k miles I have been running it, even at 182K miles now on the engine. BMW and other manufactures don't run this high of negative CC pressure as replacing gaskets for oil leaks is major $$$$$.

Under full boost you should not see any pressure or perhaps maybe 1psi max in your crankcase. Even mine with how many miles I have on the engine and running 18-21psi of boost I don't see more then 1psi Crankcase pressure under full boost at the end of a 1/4mile run. Anything more then that indicates bad check valves in your CCV system or excessive blow-by.

After you have you are sure your CCV system is good and running catch-cans still have oil out that side, only option left is to pull the turbo and check the oil return line to double check dealers work and if that checks then most likely turbo seals which you can find rebuild kits for.


EDIT: Here is one of the threads I was referring too: https://www.xbimmers.com/forums/show....php?t=1731029

Last edited by Sophisticated Redneck; 09-12-2022 at 07:01 PM..
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      05-16-2023, 11:24 AM   #5
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Quote:
Originally Posted by JohnelP View Post
Hi,

Last year I have rebuilt my N63. I have noticed there is a oil leak at the passenger side diverter valve. Before tearing the engine apart, I did not notice any leak there. When I had the engine apart, I took the turbos out as a whole, without touching the diverter valve. I have seen the PCV hoses to have oil in them, and also there is some oil in the air duct of the air inlet of the turbocharger, but that was there before. but never to the point where diverter valve leaks oil. I tried to see if there is any oil leak inside the turbocharger from the oil lubrication channels. Other thing in my mind is the oil separator from the cyl head cover. But I see that to be fairly simple so i do not see anything can go wrong with that.

Or is it too much pressure in the engine and pushes air with oil mixture too fast for the separation to take place?
I recall I have seen it once, what pressure should I measure inside the crankcase? Assume some vacuum may be there due to PCV system? Or the blow by pressure is too strong, and i may see pressure in the engine??? Don't know... Throw the topic to see what other opinions are there
Did you figure out what it was? I am having exactly the same issue on the passenger side and looks like its dripping from DV. My oil return lines have not been changed recently. But wanted to know if there is something else before I remove the turbos.
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