Looking for advice on a pesky oil leak

[325_driver 422]

So i'm hoping to pick someones brain understands maybe how the CCV system works on the N52 engine,

1. First original CCV was definitely poked, when i opened it up i could see small tears in the diaphragm, and oil was puddled in the intake manifold, 

replaced that, and seemed to fix the oil consumption problem / lean codes etc.

2. Then i saw oil building up in the same place, puddling down the engine, this was the oil pressure sensor, fixed that, engine was bone dry for a bit wahoo.

 

Then today i had a look down there, and i saw a very minimal amount of oil, built up, leaking from the intake manifold seal and making its way down the head.

Really i'm just trying to ascertain if a small amount of oil residue in the intake is pretty normal, the oil level doesn't appear to be moving (like it was)

 

So to summarize, 

1. No codes

2. Plenty of power, no rough idle, first start is perfect

3. 2-3ml of oil under the intake runners after 40km trip

 

Before i buy a smoke tester, and start chasing ghosts, i'm just trying to understand the system a bit better, and if this is normal i'm just going to live with it

a) Does anyone know whether the CCV requires negative vaccum from the crank return pipe to function 100%? it's possible it's not clicked on100%, but theres no oil leaking down there, i've checked.

b) Does the CCV remove all oil?

 

Hoping for some insight, Cheers all

 

[Jacko 2157]

Did you clean out the intake when you did the CCV? There are lots of places for oil to pool and hide in the intake

[325_driver 422]

@Jacko yeah had a bendy wire brush with hand towels wrapped round it.

[zero 1162]

Did you replace the ccv hoses too, cause they are known to block or break down.

[325_driver 422]

@zero yes, and double checked them when I put it all back in. 

Can a leak in one of those hoses lead to oil into intake? Just trying to understand how oil is finding it's way past the CCV into the intake still as it's unlikely my OEM new CCV failed, albeit plausable  I suppose.

 

[zero 1162]

I dont know much at all about the n52 motors - my ccv experience comes from the earlier n46, m54 and m62 engines. Maybe a temporary catch can will show if oils getting past the ccv?

[sweetm3 180]

When I found oil in plenum, I replaced CCV ( oil separator) and associated parts. I even added a catch can inline. 

When I last removed the air intake boot, there still was a small amount of oil sitting in my plenum. With nothing showing on the catch can dipstick.

Edited September 23, 2019 by sweetm3

[325_driver 422]

@sweetm3 so i'm not the only one with mysterious oil build up? If i'm not alone, i may just live with it? lol

[sweetm3 180]

29 minutes ago, sweetm3 said:

When I found oil in plenum, I replaced CCV ( oil separator) and associated parts. I even added a catch can inline. 

When I last removed the air intake boot, there still was a small amount of oil sitting in my plenum. With nothing showing on the catch can dipstick.

Jonathan, there was a noticeable difference in the amount of oil after the new parts were installed. 

[325_driver 422]

@sweetm3 yeah the first CCV that failed, i could see oil leaking through like all runners, and when i took the manifold off there was anywhere between 50ml-100ml of oil sloshing round in there.

I had the manifold off again when i was trying to diagnose it, and there was still some oil in there, atleast 10% of it, it wasn't a river of oil like before, but there was definitely some oil. i can see 2-3ml of oil built up underneath the 2nd intake runner forming a drip, and it returns everytime i wipe it and go for a drive.

I'm just wondering if by poor design they just might not remove all the oil in the separator and still send some through to the intake? I just don't feel comfortable with that conclusion unless someone else has had the same issue really.

Just trying to identify the likely hood of my new CCV having a pin hole in it or something, that's enough to cause a bit of oil coming through.

[Jacko 2157]

Wonder what a compression test would say.

I saw there is a procedure for checking the CCV in ISTA+, required some BMW part numbered tools, but it might be worth looking into.  Ill drag up the doc later tonight

Edited September 23, 2019 by Jacko

[325_driver 422]

@Jacko I have one of those ISTA plugs coming, so maybe booting up some software might be able to give me better insight

surely if theres oil heading in, i would expect to see it in fuel trim / limits or something

it's just not enough to trigger check engine light or something

 

[Jacko 2157]

From ISTA -

Quote

 

As a result of the combustion pressure gases are forced from the combustion chamber between the cylinder barrel and piston into the crankcase. To prevent excess pressure from being created in the crankcase, gases are directed by the vacuum in the air intake system through the crankcase ventilation system into the air intake system. The vacuum limitation is done using a pressure control valve.

Faults in the crankcase ventilation system causes a high vacuum or excess pressure in the crankcase.

The crankcase ventilation can be checked using the pressure measurement in the crankcase.

Causes of excessively high excess pressure

-	Engine damage
-	Obstruction of the crankcase ventilation
-	Faulty pressure control valve

Causes of excessively high vacuum

-	Faulty pressure control valve

Symptoms and consequences of excessively high excess pressure

-	Destruction of gaskets
-	Slip out dip stick (if applicable)
-	increased oil consumption
-	Oil in air intake system after induction site
-	Foul with oil charge air suction line in charged engines

Symptoms and consequences of excessively high vacuum

-	Destruction of gaskets
-	increased oil consumption
-	Oil in air intake system after induction site
-	Rough idle
-	Sucking or whistling noise from engine
-	Increasing number of mixed adaptation values

Setpoint values for petrol engines

The pressure control valve adjusts following pressure range:

Deviation on the current ambient pressure 0 to 30 mbar in N73: 0 to -40 mbar

Due to component and measuring tolerances the following values result for proper status:

Deviation on the current ambient pressure 0 to 30 mbar in : +20 mbar to -60 mbar in N73: +20 mbar to -70 mbar

Values in case of fault for petrol engines

A fault causes clear deviations from the values for proper status:

Crankcase ventilation "clogged": Ambient pressure +100 mbar

Crankcase ventilation "faulty": Ambient pressure -170 mbar

 

 

Im not currently connected to my car so cant bring up the program for testing, but its definitely there. 

Edited September 23, 2019 by Jacko

[M3AN 4016]

Hmm, all things considered, did you blow on the pie?

 

[325_driver 422]

@M3AN mate seriously considering it.

Maybe this cars unique feature is this tiny bit of oil consumption. 

I just need to deal with it as a fellow BMW owner.

Besides If I fix this problem another one will probably pop up. Better the devil you know I suppose

[325_driver 422]

@Jacko I thought the crank case was slightly negative vaccum? Depending on compression ring wear

[325_driver 422]

@NRJ 

right there, every time,

with the old CCV it was across every runner

with the new CCV its just a minimal amount of oil between cylinder 1-2 every time lol

I went nuts with brake cleaner when the intake was off so i can keep track of any sign of oil, oil filter housing is sweet, that was recently done

[zero 1162]

Did you check/replace the hose that goes down to the oil pan from the bottom of the oil separator?

That hose also has a ball operated check valve at its bottom bend.
It could also have been clogged making the check valve not operating.
If you remove that hose and shake it, you should hear the ball rattling at that bottom bend. Also if you blow on it from bottom side the valve should close and not allow you block. 

I would spray some electrical cleaner from the bottom side of it to make sure the check valve is area is clean and operating.

If full vacuum reaches that hose by the oil separator not functioning correctly and check valve is also not operating, the vacuum will pull engine oil from oil pan into intake manifold. 
 

[325_driver 422]

@zero I definitely replaced it, how ever this is something i want to check.

So you're saying, it's a one way valve essentially?

a) It's designed to not allow crank case pressure back up into the CCV?

b) So oil returns when that ball allows it, i.e. in the absence of vacuum / pressure?