[Jonte]

Hey. I recently bought a BMW 325i e90 N52 year 2006 which I'm experiencing is burning oil. I changed the oil for about 400km (250 miles) ago and have since then burnt around 2 liters of oil (2.11 quart). After finding out that oil had been burnt, I proceeded to make a compression test where I also checked the spark plugs. The tests showed 14.0-14.6 kg/cm2 (199-108 PSI) which sounds good to me. However, I noticed that the spark plugs in cylinder 2-6 (except for 5 which I couldn't reach) counted from the front, had A LOT of soot. The sparkplug in cylinder 1 looked pristine though. I would really appreciate it if someone could help me with this!

+----------+-------------+--------------+
| Cylinder_|Compression| Spark Plug_ |
+----------+-------------+--------------+
| 1______ | 200 PSI___| Pristine____ |
+----------+-------------+--------------+
| 2______ | 206 PSI___| Sooty_____ |
+----------+-------------+--------------+
| 3______ | 206 PSI___| Sooty_____ |
+----------+-------------+--------------+
| 4______ | 208 PSI___| Sooty_____ |
+----------+-------------+--------------+
| 5______ | Not tested | Not checked |
+----------+-------------+--------------+
| 6______ | 208 PSI___| Sooty_____ |
+----------+-------------+--------------+

Spark plug #1 compared to a sooty spark plug:

View post on imgur.com

[Saico]

I would start by changing crankcase ventilation system (PCV) although when misfunctioning all cylinders would be equally affected. The engine might be needing a major repair. Compression readings may be off while burning so much oil, I would try leakdown test you could then tell if its valve stems or rings. While replacing PCV and taking manifold off look at the valves if they're soaked in oil.

[Jonte]

Originally Posted by Saico

I would start by changing crankcase ventilation system (PCV) although when misfunctioning all cylinders would be equally affected. The engine might be needing a major repair. Compression readings may be off while burning so much oil, I would try leakdown test you could then tell if its valve stems or rings. While replacing PCV and taking manifold off look at the valves if they're soaked in oil.

Yea. I thought about the CCV as well. I just bought the car so it could be that the 1st spark plug was replaced to make the car run better or something. However, I was told by a friend that knows BMWs well, that the piston oil rings could be clogged up. It seems to be a rather common problem with the N52 engine. He advised me to try and dissolve the dirt around the piston oil rings by pouring WD40 into each cylinder and letting it be for a day.

I was told that he had a 320 E90 before that used around 1 liter of oil per week but that was fixed after doing this.

[Phil325i]

If PCV isn't the cause, I'd check injectors. If they are overfuelling this will deffo affect oil consumption. See here (yes it's an N53, but same can apply):

http://diaryofanengineer2.azurewebsi...l-consumption/

Quite a sorry tale. A massive amount of unecessary work that a fresh set of injectors alone would have cured!

[Dormermike]

Originally Posted by Phil325i

If PCV isn't the cause, I'd check injectors. If they are overfuelling this will deffo affect oil consumption. See here (yes it's an N53, but same can apply):

http://diaryofanengineer2.azurewebsi...l-consumption/

Quite a sorry tale. A massive amount of unecessary work that a fresh set of injectors alone would have cured!

Id love to know if that guy still has the car.

[Phil325i]

Originally Posted by Dormermike

Id love to know if that guy still has the car.

I think if I'd invested that amount of time, money and effort into an engine, I'd want some serious mileage out of it!

[PhaseP]

Originally Posted by Jonte

Yea. I thought about the CCV as well. I just bought the car so it could be that the 1st spark plug was replaced to make the car run better or something. However, I was told by a friend that knows BMWs well, that the piston oil rings could be clogged up. It seems to be a rather common problem with the N52 engine. He advised me to try and dissolve the dirt around the piston oil rings by pouring WD40 into each cylinder and letting it be for a day.

I was told that he had a 320 E90 before that used around 1 liter of oil per week but that was fixed after doing this.

It depends if it is N52B25 (2.5 liter) or N52B30 (3 liter version).

From what I had read N52B25 had piston rings and valve seal issues. Neither of these plague N52B30. US didn't get any N52B25s, so most people here will not be familiar with those issues.

[lab_rat]

Once the CCV and associated hoses are replaced, and the oil consumption continues, the next thing I personally would check/replace would be the valve stem seals.

Valve stem seal replacement is a bit more involved when compared to the CCV kit, though.

[iinsaneexe]

Digging up a old post. I have the same issue, good compression, some more "sooty" than the other. Replaces all gaskets and CCV system. Even put in some thicker 5W40 from liqui moly and a additive that was the consistency of honey. No dice...

Did Jonte ever solved the issue? Did WD-40 help at all?

[gT-BMW]

Originally Posted by iinsaneexe

Digging up a old post. I have the same issue, good compression, some more "sooty" than the other. Replaces all gaskets and CCV system. Even put in some thicker 5W40 from liqui moly and a additive that was the consistency of honey. No dice...

Did Jonte ever solved the issue? Did WD-40 help at all?

I'm in the same situation. I just ordered a new ccv from fcp.this is one of many parts for the brand new used engine im buying from the junkyard