[lowrydr310]

I've been consuming around 1qt of oil every 1500-2000 miles with no visible leaks or smoke out the tailpipe so I ordered a new oil separator. I have a 2006 N52 with magnesium valve cover, and the external oil separator buried under the intake manifold near the firewall, near the starter.

All the advice I read up to this point said to not even attempt to re-use the other related crankcase vent hoses (oil separator to drain tube and oil separator to intake manifold) and instead just break them off to facilitate removal. I thought I could save $100 and re-use the old hoses if I was careful. Boy was I wrong.

I had no problems with the electrical connectors, they were easy. The problem with these old hoses is that the connectors on the end of the hoses DO NOT work the way they're supposed to. When they're so old, they're very stiff and brittle. Squeezing the ring doesn't expand/release the clips the way it's supposed to. SO I did what all the experts said and I cut the hoses, making removal of the manifold very simple. If I was more patient I might have been able to remove the hoses without breaking anything, but it just wasn't worth the time.

Although after I broke the hoses and removed everything, I'm glad that I was forced to buy new ones. I discovered that the drain hole at the bottom of the oil separator along with the tube that connects to it were almost completely blocked with crud. I also couldn't pull any vacuum from the nipple on the top of the separator, indicative of a cracked diaphragm. That could explain the oil consumption I've been experiencing! I didn't break the hose from the oil separator to the intake manifold, but it too was caked with oily crud and significatnly restricted

Now I just get to wait until the new hoses arrive; until then the car is sitting in the garage. I also ordered new intake manifold gaskets too since the existing ones are very stiff and I'm not confident they will seal well, and I don't want to do this job again any time soon.

[hassmaschine]

yeah, whenever you touch the PCV system on an E90 - just assume that the plastic hoses are going to break.

How many miles are on your car? It seems like the PCV systems can last a long time, but they do plug up and cause oil use issues eventually.

You should do a 3-stage swap since you have it apart anyway. you've done 99.9% of the hard stuff. Also, consider replacing the starter if it's original (and especially if it cranks over slowly).

[lowrydr310]

Originally Posted by hassmaschine

yeah, whenever you touch the PCV system on an E90 - just assume that the plastic hoses are going to break.

How many miles are on your car? It seems like the PCV systems can last a long time, but they do plug up and cause oil use issues eventually.

You should do a 3-stage swap since you have it apart anyway. you've done 99.9% of the hard stuff. Also, consider replacing the starter if it's original (and especially if it cranks over slowly).

I didn't break any hoses, not this time at least. When I replaced the valve cover gasket last year I did brake that hose, however I repaired it using self-sealing silicone tape which worked well.

I have 230K miles on the car and the hoses appear to be original. After going through all the effort to remove the manifold, I considered the starter but it turns over just fine. It's difficult to tell but it may have been replaced already as it looks a little cleaner than the rest of the engine.

I considered the 3 stage manifold swap, but that's an extra expense that is being used to replace the shocks and struts at the moment.

[Efthreeoh]

Low, what do the valves look like with all that oil vapor passing over them? Walnut blasting required?

I'm pretty sure my CCV is in the same shape yours was in.

[hassmaschine]

Should be pretty clean. Remember, fuel is sprayed on them - which is a really great solvent. it would have to be pretty bad to need walnut blasting. even my 280k parts motor looked relatively clean on the ports.

[lowrydr310]

The valves and the intake ports are extremely clean, except for a thin coating of oil near the top of the port where the manifold runners mate to it. I'll snap some pictures before I put it all back together. Port injection for the win here! Just wait until you see the picture of the oil return hose.

The throttle plate was covered in grime but cleaned off easily with throttle body cleaner. But that's (normally) always open when the engine is running so it isn't an issue.

[Efthreeoh]

Originally Posted by lowrydr310

The valves and the intake ports are extremely clean, except for a thin coating of oil near the top of the port where the manifold runners mate to it. I'll snap some pictures before I put it all back together. Port injection for the win here! Just wait until you see the picture of the oil return hose.

The throttle plate was covered in grime but cleaned off easily with throttle body cleaner. But that's (normally) always open when the engine is running so it isn't an issue.

Good deal. Knowing the fuel keeps carbon deposits away since it's port injected is one thing, I was just concerned that an extraordinary amount of oil in the airstream may overcome the fuel detergent.

[Efthreeoh]

Originally Posted by hassmaschine

Should be pretty clean. Remember, fuel is sprayed on them - which is a really great solvent. it would have to be pretty bad to need walnut blasting. even my 280k parts motor looked relatively clean on the ports.

At 378, and a failing separator (I think), I'm a little concerned about my car. But the engine pulls as strong as ever though...

[leif20]

My engine theory is a little rusty... What about a failing separator causes increased oil consumption?

[hassmaschine]

It's a vacuum leak in the oil system basically. What happens is crankcase pressure leaks out where it shouldn't (the intake) and it ends up sucking extra oil from the crankcase.

Once on my M20 the o-ring to the crankcase vent wasn't seated right. It sucked like a quart of oil into the intake in 100 miles. The airbox was full of oil, the filter totally soaked.

[leif20]

So 1 is the separator itself. I noticed a bunch of oil buildup at the entrance where pipe #3 vents to the separator. If this port is clogged, does the separator then start pulling in oil (under vacuum) from the port at 4? The feed to the intake is pipe #2.

When I did the starter back in December I noticed my intake was covered with a light film of oil, all over. There was so much in it actually that it pooled a little in the low parts of the manifold. Based on the above It seems that this could be due to a clogged up separator? I am also having some consumption issues, probably 1qt in 3000mi.

[porsche959]

Originally Posted by lowrydr310

I've been consuming around 1qt of oil every 1500-2000 miles with no visible leaks or smoke out the tailpipe so I ordered a new oil separator. I have a 2006 N52 with magnesium valve cover, and the external oil separator buried under the intake manifold near the firewall, near the starter.

All the advice I read up to this point said to not even attempt to re-use the other related crankcase vent hoses (oil separator to drain tube and oil separator to intake manifold) and instead just break them off to facilitate removal. I thought I could save $100 and re-use the old hoses if I was careful. Boy was I wrong.

I had no problems with the electrical connectors, they were easy. The problem with these old hoses is that the connectors on the end of the hoses DO NOT work the way they're supposed to. When they're so old, they're very stiff and brittle. Squeezing the ring doesn't expand/release the clips the way it's supposed to. SO I did what all the experts said and I cut the hoses, making removal of the manifold very simple. If I was more patient I might have been able to remove the hoses without breaking anything, but it just wasn't worth the time.

Although after I broke the hoses and removed everything, I'm glad that I was forced to buy new ones. I discovered that the drain hole at the bottom of the oil separator along with the tube that connects to it were almost completely blocked with crud. I also couldn't pull any vacuum from the nipple on the top of the separator, indicative of a cracked diaphragm. That could explain the oil consumption I've been experiencing! I didn't break the hose from the oil separator to the intake manifold, but it too was caked with oily crud and significatnly restricted

Now I just get to wait until the new hoses arrive; until then the car is sitting in the garage. I also ordered new intake manifold gaskets too since the existing ones are very stiff and I'm not confident they will seal well, and I don't want to do this job again any time soon.

Thinking about this repair myself. Thanks for detailing your experience. I have a 2006 325i - which is the same engine.

Do you have a list of parts you bought for the repair? Any links?

Also when you cut the hoses, did you just cut them in the middle or just break/cut the connector?

[lowrydr310]

Originally Posted by porsche959

Thinking about this repair myself. Thanks for detailing your experience. I have a 2006 325i - which is the same engine.

Do you have a list of parts you bought for the repair? Any links?

Also when you cut the hoses, did you just cut them in the middle or just break/cut the connector?

Rock auto sells a complete set of everything you need. I initially just purchased the oil separator itself thinking I was going to save money, but ended up having to buy the valve cover vent hose goign to the oil separator (#3 in the drawing posted earlier), oil separator to oil pan hose (#4 in the above drawing), and oil separator to intake hose. Apparently there are two styles for the last hose going from the separator to the intake manifold; the #2 hose in that drawing posted above is a single tube going to the intake manifold. I beleive that was for earlier models prior to 10/05. For models made after 10/05 such as mine, it's a single connection to the oil separator that splits into two pieces that each connect to the intake manifold.

I just ripped the valve cover hose however I used a utility knife to cut the drain hose that goes back to the oil pan. The hose going to the manifold doesn't need to be cut since you can access the connectors easily; while the connectors couldn't be released due to being brittle, I used a screwdriver to snap them off and the hoses pulled out easily.

When reinstalling new hoses, one little tip I learned is to lubricate the O-rings. I had difficulty reconnecting the lower end of the hose that goes to the oil pan return because it was dry, but easily slid in once it was lubricated.



One observation after doing this job is that I still have the same amount of suction present at the oil fill cap as I had before replacing the oil separator and hoses. I thought this would have been reduced. It doesn't *seem* excessive, however it still requires some effort to lift the sealed oil fill cap to open it and if I open it slightly I can hear it hissing.

Prior to replacing everything I was consuming about a quart of oil every 1500-2000 miles. When I finished installing everything last weekend, I already had the +1qt message so I added a quart of oil to get a baseline (new oil separator and hoses, topped off with oil) to see if oil consumption is reduced with a new separator. Once warmed up, I saw a full measurement on the electronic dipstick, so all was good. That was Sunday.

I've since driven about 150 miles over the past five days and I checked the oil level on the e-dipstick this morning and it's in the middle between the low and high marks. This is very odd. Usually it'll remain at the full mark for a while and as I drive more and more I'll see it decrease in 1/4 increments, until it gets to the bottom mark and I get the "+1qt" message. I'm not sure if I'm actually consuming a ton of oil or if this is some odd behavior with my oil level sensor. There isn't even a single drop of oil in my garage, no smoke from under the hood, and there is ZERO smoke out the tailpipe. My cousin once had a civic that consumed a quart of oil in 500 miles and it made an obscene amount of smoke. I don't have that.

Just for reference, the oil level sensor always seems to work correctly. For example, whenever I got the +1qt message before and it was time for an oil change, slightly less than 6 quarts of oil would drain out. Regardless, I'm not adding any oil since I'm not getting the "+1qt" message and I will continue to monitor and post an update here.

UPDATE: Driving home from work today (same day I posted this) it was showing 3/4. Then after driving again later in the evening it's showing full. Bad oil level sensor?

[leif20]

A couple threads that are relevant:
https://www.e90post.com/forums/showt...=225629&page=2
In some manifolds the hose to the IM has a split, to prevent the CCV from pointing directly at the throttle body. I experienced a stuck throttle in extreme cold earlier this year, possibly due to having water vapor condense on it.

Here is a full disassembly of the unit. This should help to answer my flow questions.
https://www.e90post.com/forums/showthread.php?t=1312867

Originally Posted by lowrydr310

Rock auto sells a complete set of everything you need. I initially just purchased the oil separator itself thinking I was going to save money, but ended up having to buy the valve cover vent hose goign to the oil separator (#3 in the drawing posted earlier)

Was the hose that came in this kit the right size for you? I bought just this hose off amazon last year in anticipation of having to replace it when doing my starter, but it was about 5mm too short. Not sure if it was meant for the newer manifolds but I had to reuse my old one, which was fine. It's possible i bought the wrong part.

Originally Posted by lowrydr310

UPDATE: Driving home from work today (same day I posted this) it was showing 3/4. Then after driving again later in the evening it's showing full. Bad oil level sensor?

I think it's quite common that the EDS will take some time to give an accurate reading. It seems to work pretty well in general.

[lowrydr310]

Originally Posted by leif20

Was the hose that came in this kit the right size for you? I bought just this hose off amazon last year in anticipation of having to replace it when doing my starter, but it was about 5mm too short. Not sure if it was meant for the newer manifolds but I had to reuse my old one, which was fine. It's possible i bought the wrong part.

I think it's quite common that the EDS will take some time to give an accurate reading. It seems to work pretty well in general.

I didn't buy that kit so I can't comment on the hose length. I purchased everything separately, except for the heated elbow since the local dealer is eventually going to replace that for free under the recall.

I know the oil level sensor (OZS) does take time to give an accurate reading, however what I'm describing is a completely new symptom. I've had the car over a year and put approximately 15000 miles on it, and the behavior was consistently the same up until recently. I know exactly how it's supposed to work, and it was doing just that. I never had the reading jump around like it's doing now.

Next time I do get the +1QT message (or 1500 more miles, whichever comes first) I'm going to do an oil change so I'll confirm how much drains out.

[Efthreeoh]

Originally Posted by lowrydr310

I didn't buy that kit so I can't comment on the hose length. I purchased everything separately, except for the heated elbow since the local dealer is eventually going to replace that for free under the recall.

I know the oil level sensor (OZS) does take time to give an accurate reading, however what I'm describing is a completely new symptom. I've had the car over a year and put approximately 15000 miles on it, and the behavior was consistently the same up until recently. I know exactly how it's supposed to work, and it was doing just that. I never had the reading jump around like it's doing now.

Next time I do get the +1QT message (or 1500 more miles, whichever comes first) I'm going to do an oil change so I'll confirm how much drains out.

I think that's the right approach. I'd not yet get concerned over the oil sensor because there is no logical reason the sensor would malfunction just at the same time the CCV was changed out. I'm going to change my CCV out soon, so we'll see what happens on my car. It's pretty much behaving like your car pre CCV swap out.

[leif20]

Alright so I think my oil consumption issue is a bit worse than I originally thought. Looks like I'm burning a quart in about 2000mi.

How long can I drive like this? I'd rather not do the oil separator for a few weeks, but I also drive about 500mi per week (including weekend trips). I think the only issue is that with enough oil burning the catalyst will have reduced function, and eventually get clogged up, which is obviously not desirable. But I think this will probably take a while to happen. Does anyone have any thoughts on this? I don't think the ports will get dirty as the port injection keeps them clean, when I did my starter in the fall they were clean as a whistle.

Based on my understanding here and my experience taking off my intake (seeing a film of oil on the manifold and pooling in some spots), I think doing the oil separator will help with this consumption issue.

[Efthreeoh]

Originally Posted by leif20

Alright so I think my oil consumption issue is a bit worse than I originally thought. Looks like I'm burning a quart in about 2000mi.

How long can I drive like this? I'd rather not do the oil separator for a few weeks, but I also drive about 500mi per week (including weekend trips). I think the only issue is that with enough oil burning the catalyst will have reduced function, and eventually get clogged up, which is obviously not desirable. But I think this will probably take a while to happen. Does anyone have any thoughts on this? I don't think the ports will get dirty as the port injection keeps them clean, when I did my starter in the fall they were clean as a whistle.

Based on my understanding here and my experience taking off my intake (seeing a film of oil on the manifold and pooling in some spots), I think doing the oil separator will help with this consumption issue.

My consumption is a little bit better than yours, around 2,500 - 3,000 miles per liter. It's been running that consumption rate for over a year, so about 28,000 miles. No cat codes. BMW spec is 1L/600 miles IIRC. So I think you can not stress over it.

[lowrydr310]

Originally Posted by leif20

I think the only issue is that with enough oil burning the catalyst will have reduced function, and eventually get clogged up, which is obviously not desirable. But I think this will probably take a while to happen. Does anyone have any thoughts on this? I don't think the ports will get dirty as the port injection keeps them clean, when I did my starter in the fall they were clean as a whistle.

Based on my understanding here and my experience taking off my intake (seeing a film of oil on the manifold and pooling in some spots), I think doing the oil separator will help with this consumption issue.

I bought my car over a year ago and put about 15000 miles on it so far, and I was burning a quart every 1500-2000 (it varied). I too was concerned about the catalytic converter which is what motivated me to replace the oil separator. During the time I've owned the car I never had a check engine light or any other issue related to the catalytic converter.

Intake ports are extremely clean. I have some pictures I'll share once I get them transferred to my computer and resized.

When I removed my intake manifold I too had a pool of oil inside that dumped out, easily a few ounces so I was pretty sure I found the source of the consumption. After my little issue above with the oil level indicator bouncing around a few times it's holding pretty solid at the halfway mark but I haven't driven enough mileage to conclusively say my consumption was reduced just yet.

When I was about halfway into the job and successfully removed the separator and all related tubing, I told myself that I would rather keep adding oil than have to do that job again, though I am glad I replaced it. I'm pretty competent when it comes to repairs. I've dismantled engines to replace pistons and rings, and this was the most difficult job I've ever tackled. I guess it's because of how simple of a function the separator performs, yet it's not easily accessible or serviceable. However since you've already had the manifold removed then you know exactly what's involved. I am curious about how you managed to disconnect all the existing CCV plumbing without breaking anything.

If I had to do this again I was thinking it would be a lot easier using generic heater hose and hose clamps instead of the specialized plastic tubes with integrated heater wires. What would be the downside of this? I only experience outside temperatures in the upper 30s about 3-4 days a year so I'm not worried about condensation.

[leif20]

Originally Posted by lowrydr310

When I was about halfway into the job and successfully removed the separator and all related tubing, I told myself that I would rather keep adding oil than have to do that job again, though I am glad I replaced it. I'm pretty competent when it comes to repairs. I've dismantled engines to replace pistons and rings, and this was the most difficult job I've ever tackled. I guess it's because of how simple of a function the separator performs, yet it's not easily accessible or serviceable. However since you've already had the manifold removed then you know exactly what's involved. I am curious about how you managed to disconnect all the existing CCV plumbing without breaking anything.

Going in to the job I knew how much of a pain it was going to be, and that would likely be breaking hoses. I took my time and did as much as I could to release them carefully. I think I cracked clips on a couple but most of them came off OK. None of the hoses disintegrated. The cracked ones still held in place when reassembled so i didn't worry. My valve cover to separator hose had a clip that broke completely and the replacement hose was a few mm too short which was super shitty so I took the new clip off that and reuse the old hose.

I felt the same way about the starter - I used a cheap one from rockauto, and told myself that if this one ever fails im going to be super pissed that I didnt use a better made one, to have to go through the job again.

This is at least a half day job, if not full day, so it's kind of daunting knowing i'll have to do it again

I just did transmission solenoids (had to drop the pan twice due to an error), so the $500 it cost to do that and the full day of work is fresh in my mind. I'd rather not get tits-deep in this car again for a while. Just want to enjoy the summer. I do want to stop this oil consumption, but maybe I'll wait until the spring.

The Heater hose Idea is an interesting one. Since you're unlikely to have condensation maybe it will work? The intake has a power distribution box on it for the separator and hose, so perhaps it will report a fault for current/voltage below threshold if you take out some of those resistors (heated hoses)?

[hassmaschine]

On our E91, the hoses were routed *under* the starter wiring. There was literally no way to get to the clips to release them, because the manifold couldn't be moved more than 1/2". I was forced to break the hoses.

[lowrydr310]

Originally Posted by lowrydr310

Prior to replacing everything I was consuming about a quart of oil every 1500-2000 miles. When I finished installing everything last weekend, I already had the +1qt message so I added a quart of oil to get a baseline (new oil separator and hoses, topped off with oil) to see if oil consumption is reduced with a new separator. Once warmed up, I saw a full measurement on the electronic dipstick, so all was good. That was Sunday.

I've since driven about 150 miles over the past five days and I checked the oil level on the e-dipstick this morning and it's in the middle between the low and high marks. This is very odd. Usually it'll remain at the full mark for a while and as I drive more and more I'll see it decrease in 1/4 increments, until it gets to the bottom mark and I get the "+1qt" message. I'm not sure if I'm actually consuming a ton of oil or if this is some odd behavior with my oil level sensor. There isn't even a single drop of oil in my garage, no smoke from under the hood, and there is ZERO smoke out the tailpipe. My cousin once had a civic that consumed a quart of oil in 500 miles and it made an obscene amount of smoke. I don't have that.

Just for reference, the oil level sensor always seems to work correctly. For example, whenever I got the +1qt message before and it was time for an oil change, slightly less than 6 quarts of oil would drain out. Regardless, I'm not adding any oil since I'm not getting the "+1qt" message and I will continue to monitor and post an update here.

UPDATE: Driving home from work today (same day I posted this) it was showing 3/4. Then after driving again later in the evening it's showing full. Bad oil level sensor?

Quoting myself here just for reference. I'm not crazy, I promise.

After that odd behavior with the oil level bouncing around it appears to have stabilized. It did show full at one point, then quickly dropped back down to 3/4 and and it's been steadily dropping since then. In two weeks and after driving approximately 500 miles since replacing my oil separator and topping off a quart, I'm down to the 1/4 level. What's going on here?

One thing I remember is that prior to the oil separator replacement, I did seem to consume a bit more oil than usual. I've typically seen 1500-2000 miles before having to add a quart but I recall having to add two quarts over approximately 2000 miles in June-July. I've also done a lot less steady freeway driving and much more stop and go sitting in traffic. So the consumption after the oil separator and CCV hose replacement is pretty much in line with where it was prior.

I get that it's a 13 year 200K mile German car so some oil consumption is expected, but I'm baffled by stories of other N52 owners who claim they can go on 10K mile OCIs with either no consumption or minimal (<1qt) over that period.

I read quite a few reports of the M54 having worn oil control rings, or even stuck oil rings after a CCV failure. There's nothing short of a ring replacement to fix a worn ring, but I have heard of a few people doing a piston soak and/or oil additives to the crankcase oil to help free them up if stuck. Is it worth pursuing one of these snake oil cures on the N52?

Prior to purchasing my car, the previous owner had a misfire due to a failed coil on the #3 cylinder and had likely driven it with the misfire for some time. When I replaced coils and plugs, the old #3 spark plug was black and looked oil fouled while the others looked fine. I guess it's time to pull plugs and check what's going on.