Cute little trick to diagnose blocked CCV system...

My dipstick sucked in slightly.
What does this mean?

The amount that can be learned in this forum is mind boggling!

Originally Posted by cn90

Poolman,

Dipstick housing represents crankcase prssure, so it is almost always high from blow-by combustion. The dipstick can never suck in.

Vacuum exist in the Intake Manifold only.

cn90,

Actually I just did this test and I got definite, though very light suction at the dipstick tube and extremely heavy suction at the oil filler. Not sure what would cause this (dipstick tube vacuum) but I'm trying to diagnose a possible CVV failure.

Originally Posted by rdl

...

Since there have been so many questions on the topic of CCV operation and failure, here is a description of how I think the CCV operates using Bluebee's picture for reference.

The vent pipe, swirl labyrinth chamber and vent hose are always at the same pressure or vacuum - there is no valve or obstruction between them. The swirl labyrinth is the lower part of the CCV assy that the vent pipe & vent hose connect to. Further, they connect to the valve cover & crankcase without restriction and are at crankcase pressure/vacuum.

The connecting line and return pipe connect to the inlet manifold which has a vacuum of ~20 inches Hg (mercury) at idle; ~260 inches water column vacuum.

The portion of the CCV immediately beside the blue "CCV" label in Bluebee's picture is a vacuum regulator whose job it is to maintain 4 -6" w.c. vacuum in the swirl chamber.

When the engine starts, the labyrinth is at 0 vacuum (i.e. vacuum is less than 4" w.c.) & the orifice/valve in the regulator is open. The gases in the swirl chamber flow through the regulator into the connecting line (which is at high vacuum), on to the inlet manifold and through the engine. Soon the vacuum in the swirl chamber (also the crankcase to which it is connected) is sucked down to 4 - 6" w.c. vacuum and the orifice valve in the regulator closes.

The engine runs, more blowby gases from the combustion chamber enter the crankcase & raise the pressure (reduce vacuum) in the vent pipe & swirl chamber. The regulator opens again, allows manifold vacuum in the connecting line to suck them away until crankcase vacuum is back to 4 - 6" w.c. at which point the regulator closes again. And on it goes, cycling over and over.

As the blowby gas travels through the engine toward the CCV, it picks up microscopic droplets/mist of oil. We don't want this oil mist to go through the vacuum regulator, into the inlet manifold and be burned: high oil consumption and air pollution. Enter the swirl labyrinth; it causes oil droplets/mist in the blowby gases to stick to the wall of the labyrinth and drain down the vent hose into the dipstick tube and sump while the "cleaned" gases carry on through the regulator.
...
Regards
RDL

Great explanation RDL, but I disagree with one part of your analysis. I think the diaphragm in the CCV is operated by intake manifold pressure rather than crankcase pressure.

I cut a CCV apart and found a couple of interesting issues. First, the bottom part, which I call the cyclonic separator, and the top part, which I call the regulating valve are connected with a small tube. This is the tube with the vacuum nipple that controls the FPR on earlier models, This tube is hollow, but extends all of the way through the cyclonic separator and is the part to which the drain tube (vent hose) is attached. This tube is continuous from the regulating valve to the drain tube and is only perforated by a few slots just above where the tube exits the bottom of the cyclonic separator..

Also, the web inside the cyclonic separator is a continuous spiral. The outside of the spiral attaches to the cyclonic separator body at the entrance of the vent pipe. The inner part of the spiral web is attached to the central tube.

The central tube connects to the regulating valve on the same side of the diagram as connecting line to the intake manifold. Inside the regulating valve the diaphragm works in opposition to a spring on the vacuum side of the diaphragm. So the diaphragm that closes off the passage of gasses from the cyclonic separator is exposed to vacuum from both the crankcase and the intake manifold.

I think the intake manifold vacuum will always be higher than the crankcase vacuum. So I think the diaphragm opens when the intake manifold vacuum is lowered(is closer to atmospheric pressure) as the throttle plate opens. This mode of operation would route the blowby gasses into the intake manifold when engine speed is high and air intake volume is high.

Originally Posted by Steve530

Great explanation RDL, but I disagree with one part of your analysis. I think the diaphragm in the CCV is operated by intake manifold pressure rather than crankcase pressure.
... stuff deleted ...

The central tube connects to the regulating valve on the same side of the diagram as connecting line to the intake manifold. Inside the regulating valve the diaphragm works in opposition to a spring on the vacuum side of the diaphragm. So the diaphragm that closes off the passage of gasses from the cyclonic separator is exposed to vacuum from both the crankcase and the intake manifold.

I think the intake manifold vacuum will always be higher than the crankcase vacuum. So I think the diaphragm opens when the intake manifold vacuum is lowered(is closer to atmospheric pressure) as the throttle plate opens. This mode of operation would route the blowby gasses into the intake manifold when engine speed is high and air intake volume is high.

I agree with much of your description but I think you misunderstand how the pieces are working together as a system. Whether the diaphram port is open or closed depends on vacuum in the CCV , not inlet manifold vacuum.

1 When the engine is started the CCV valve chamber is at atmospheric pressure, no vacuum.
2 The spring is pushing the diaphram away from the center port that is connected to the inlet manifold. So, there is an open passage from the crankcase, through the CCV to the inlet manifold.
3 The open passage allows manifold vacuum (engine now running) to suck air & blowby gases from the swirl chamber through the center port, eventually creating a vacuum inside the regulating valve chamber (and crankcase too, of course)
4 Now the diaphram will be pushed against the spring by atmospheric (higher) pressure on the other side of the diaphram. As the vacuum increases, the diaphram moves closer & closer to the port connected to the inlet manifold.
5 Eventually the diaphram compresses the spring enough that it touches the vacuum port and seals it off. This stops the inlet manifold from sucking any more from the swirl chamber. For an instant the vacuum on the swirl chamber is constant.
6 Next, blowby getting past the piston rings enters the swirl chamber & moves up into the regulating valve chamber which reduces the vacuum.
7 With reduced vacuum, the spring is able to move the diaphram and open the vacuum port to the inlet manifold again
8 Vaccum inside the chamber is again sucked down - around & around it goes.

So the vacuum in the CCV, and crankcase, is generated by inlet manifold vacuum and controlled by the CCV regulating valve. As long as the CCV is operating correctly, inlet manifold vacuum will always be greater than CCV/crankcase vacuum.

The size (diameter) of the diaphram, its flexibility/stiffness, strength of the spring and the relative position of diaphram & center port are worked out by the designer so that diaphram is just touching, i.e. closing off, the center port at a vacuum of 10 to 15 millibar (4 to 6 inches water column) in the CCV.

If my explanation isn't clear, try Wikipedia and Google for "pressure regulator" or "welding regulator" for a better description. The function is a little different than the CCV since these are reducing a high pressure to a lower working pressure. But the principal is the same: a diaphram or piston pushing against a spring is opening & closing a port allowing the gases to flow from higher pressure to lower pressure.

Originally Posted by rdl

...
6 Next, blowby getting past the piston rings enters the swirl chamber & moves up into the regulating valve chamber which reduces the vacuum.
7 With reduced vacuum, the spring is able to move the diaphram and open the vacuum port to the inlet manifold again
8 Vaccum inside the chamber is again sucked down - around & around it goes.,,,

This is where we disagree. As I recall, the vacuum from the intake manifold and the crankcase are applied to the same side of the diaphragm. I do not remember seeing any part of the diaphragm that was molded to fit the tubes or any sort of special port. Just a diaphragm that moves against a spring to close off those two ports. Anyway, I'll take another looks at the diaphragm.

BTW, I was thinking about measuring the vacuum that must be applied to the CCV to close the diaphragm. Have you done that or do you have any advice about how to measure the vacuum required to close the diaphragm?

Originally Posted by Steve530

This is where we disagree. As I recall, the vacuum from the intake manifold and the crankcase are applied to the same side of the diaphragm. I do not remember seeing any part of the diaphragm that was molded to fit the tubes or any sort of special port. Just a diaphragm that moves against a spring to close off those two ports. Anyway, I'll take another looks at the diaphragm.

BTW, I was thinking about measuring the vacuum that must be applied to the CCV to close the diaphragm. Have you done that or do you have any advice about how to measure the vacuum required to close the diaphragm?

Yes, manifold vacuum and crankcase vacuum, or pressure, are applied to the same side of the diaphram. Except of course, manifold vacuum is blocked off when the diaphram moves far enough against the spring to touch the port connected to the inlet manifold. The port from the swirl chamber (crankcase) is never blocked. The diaphram isn't molded in a special shape to block off both ports. The flat center of the diaphram moves to touch or not touch (block or open) only the port in the center of the the regulator chamber which is connected to the inlet manifold.

This is the crucial point; crankcase vacuum (or pressure) is always present. Inlet manifold vacuum is "switched" on & off by the diaphram to control crankcase vacuum at 10 - 15 millibar.

Perhaps it will help to point out that when the diaphram opens the manifold vacuum port, crankcase vacuum does not instantaneously go to to full manifold vacuum. Rather it begins reducing crankcase pressure (increasing vacuum) as blowby gases are sucked into the inlet manifold. As crankcase vacuum approaches 10 - 15 millibar, the diaphram blocks the manifold port again, limiting crankcase vacuum.

So, the vacuum at which the diaphram closes off the inlet manifold port (i.e. center) is crankcase vacuum. See this thread for measurement methods
http://www.bimmerfest.com/forums/sho...95#post5989795
Posts 7 & 8 suggest specific methods to measure this vacuum (or heaven forbid, pressure. )

As someone who is currently involved with a redesign of the CCV, and studied the system extensively, I can tell you that rdl is 100% correct in his description of how the system functions. In fact it is by far the best technical description I have seen to date.

Good job.

Gary

I looked at the diaphragm again. I can confirm that the diaphragm does indeed close off the vacuum to the intake manifold and that the crankcase vacuum is not closed off by the diaphragm when the the diaphragm is closed. I'll post a few pictures later today.

Originally Posted by gary@germanautosolutions

As someone who is currently involved with a redesign of the CCV, and studied the system extensively, I can tell you that rdl is 100% correct in his description of how the system functions. In fact it is by far the best technical description I have seen to date.

Good job.

Gary

Do you know the pressure at which the diaphragm closes?

I looked at the diaphragm again. I can confirm that the diaphragm does indeed close off the vacuum to the intake manifold and that the crankcase vacuum is not closed off by the diaphragm when the the diaphragm is closed.

I think we are all on the same page here. The diaphagm isolates the manifold vacuum (approx 260 inches of water) from the crankcase once the crankcase vacuum reaches 4-6 inches of water. The diaphagm modulates opening and closing the port to the intake manifold which regulates the crankcase vacuum to 4-6 inches of water.

Gary

Originally Posted by gary@germanautosolutions

I think we are all on the same page here. The diaphagm isolates the manifold vacuum (approx 260 inches of water) from the crankcase once the crankcase vacuum reaches 4-6 inches of water. The diaphagm modulates opening and closing the port to the intake manifold which regulates the crankcase vacuum to 4-6 inches of water.

Gary

Thanks.

Here are two photos.

The first shows the opened vacuum regulator. This shows the diaphragm, the spring and the case. Note that the diaphragm seals off the hose going to the intake manifold, but does not seal off the central tube that allows gases to flow from the oil separator. The central tube and oil separator are at crankcase pressure.



The Second photo shows the oil separator of the CCV. I passed a red wire around the spiral to show the path of the gasses and show that it is a spiral. Note I drew the yellow line to show the inner edge of the spiral web on the oil separator. The oil and gasses enter from the left and travel along the spiral path until it reaches the central tube.

Steve,

It looks like both pictures that you uploaded are the same.

I'm still a little confused as to whether you agree with me and RDL on how the system functions, or if you are still taking an opposing view. I'm not trying to be sarcastic in any way, I'm just not sure if we are on the same page yet.

Thanks,

Gary

I'm here searching for a definitive way to test whether the steel CCV vent tube (integral with the oil dipstick guide tube) is clogged.

Mine was totally clogged recently.

I cleaned it out - but - how would I know when it becomes clogged again?
All the diagnostics I found were for testing the CCV itself, not for testing the steel vent tube.


BTW: I live in a warm clime ... where it (almost) never freezes ... and hardly ever rains ... so ... that tells me (almost) EVERYONE needs to check to see if their dipstick guide tube is clogged (unless they have a retrofit).

Q: Without removing it, what test, if any, will tell us the dipstick guide tube is clogged?

So the fuel pressure regulator in M52, connected to CCV is operated with crankcase vacuum?

Originally Posted by Zakov

So the fuel pressure regulator in M52, connected to CCV is operated with crankcase vacuum?

I have an M54 so I'm not really familiar with your engine. I have though seen the pictures and diagrams of the air hose off the CCV running to the fuel pressure regulator.

When I first saw those pictures a couple of years ago, I was baffled at the design intent. I finally realized that "operated with crankcase vacuum" is technically accurate. But assuming the CCV is working properly it is really so close to atmospheric pressure that it makes no practical difference. The CCV regulates crankcase vacuum to less than 15 millibar, or EDIT 1.5% (not 0.15% in original post) different from atmospheric pressure.

I think the purpose of taking a reference pressure this way is to provide clean, filtered source of atmospheric pressure to the fuel pressure regulator without any chance of engine bay dirt, grit and grime fouling the sensitive parts of the small fuel pressure regulator. By comparision, the CCV is about 3 inches in diameter & much less sensitive to dirt. An awkward, klugey way to achieve the result in my opinion.

For the M54, BMW changed the design to take atmospheric reference pressure from the F fitting in the boot between the MAF and inlet manifold. That supply is kept clean by the engine air cleaner.

Originally Posted by Zakov

So the fuel pressure regulator in M52, connected to CCV is operated with crankcase vacuum?

I typed /m52 ccv F3 in the bestlinks and it came up with this thread which covers that issue in exquisite detail:
- Sorely needed clarification on how the M54 CCV vacuum port works on the M52 CCV valve connection to the fuel pressure regulator connection (1)

Originally Posted by rdl

I think the purpose of taking a reference pressure this way is to provide clean, filtered source of atmospheric pressure to the fuel pressure regulator

So that all benefit, I appended this nice & interestingly logical information to that thread discussing, in detail, how the system seems to work.
- WHERE does the CCV vacuum source port go for the E39 CCV valves that are not plugged?

EDIT:
I tried to test the CCV system by checking manifold vacuum, as shown here - but I think I failed to conclude much of anything:
- How to test the crankcase ventilation pressure regulating valve system (1)

Originally Posted by bluebee

... stuff deleted ...

EDIT:
I tried to test the CCV system by checking manifold vacuum, as shown here - but I think I failed to conclude much of anything:

... stuff deleted ...

I think you mean crankcase rather than manifold vacuum?
Why did you fail to conclude much of anything.

Originally Posted by rdl

I think you mean crankcase rather than manifold vacuum?

Hmmm... good point. Which vacuum 'did' I test (crankcase? or manifold?) when I ran the inconclusive vacuum test?

Looking back here, I see I wrote:

DIPSTICK GUIDE TUBE VACUUM:
1. Using a 5/8" ID rubber tube about three feet long, my M54 vacuum at idle at the dipstick guide tube was just under 8 inches of water.

So, it appears you are correct in that the dipstick guide tube should be crankcase vacuum. Right?

Originally Posted by rdl

Why did you fail to conclude much of anything.

Well, here are my data points:

1. Original CCV (2002 model year)
2. Warm dry weather (Silicon Valley)
3. 8 inches of "crankcase" vacuum
4. Vent pipe blow test showed no resistance
5. No misfires
6. Dipstick 'was' clogged solid - but it has been cleaned out
7. No smoke whatsoever on exhaust (California smog tests are nearly perfect)

Given that conflicting information, I'm not sure WHAT the state of the CCV is in.

Originally Posted by rdl

I have an M54 so I'm not really familiar with your engine. I have though seen the pictures and diagrams of the air hose off the CCV running to the fuel pressure regulator.

When I first saw those pictures a couple of years ago, I was baffled at the design intent. I finally realized that "operated with crankcase vacuum" is technically accurate. But assuming the CCV is working properly it is really so close to atmospheric pressure that it makes no practical difference. The CCV regulates crankcase vacuum to less than 15 millibar, or EDIT 1.5% (not 0.15% in original post) different from atmospheric pressure.

I think the purpose of taking a reference pressure this way is to provide clean, filtered source of atmospheric pressure to the fuel pressure regulator without any chance of engine bay dirt, grit and grime fouling the sensitive parts of the small fuel pressure regulator. By comparision, the CCV is about 3 inches in diameter & much less sensitive to dirt. An awkward, klugey way to achieve the result in my opinion.

For the M54, BMW changed the design to take atmospheric reference pressure from the F fitting in the boot between the MAF and inlet manifold. That supply is kept clean by the engine air cleaner.

I think some of the posts are incorrect. The vac hose effect is to reduce rail pressure at idle, by increasing bypass fuel flow. The cases where hose is tied to cvv may have additional effect to increase rail pressure at high rpm.

Originally Posted by bluebee

... stuff deleted ...
Well, here are my data points:

1. Original CCV (2002 model year)
2. Warm dry weather (Silicon Valley)
3. 8 inches of "crankcase" vacuum
4. Vent pipe blow test showed no resistance
5. No misfires
6. Dipstick 'was' clogged solid - but it has been cleaned out
7. No smoke whatsoever on exhaust (California smog tests are nearly perfect)

Given that conflicting information, I'm not sure WHAT the state of the CCV is in.

... stuff deleted ...

Two years ago, my car failed vacuum at 9 inches but had no symptoms at all: engine performance & idle qualtity were normal, no DTCs were present and no smoke from the tailpipe. A couple of months later the CCV system failed entirely. The engine then refused to idle, generated a raft of DTCs and lit up the CEL. Even after failure, I had no smoke. However, while replacing the entire CCV system I discovered a hole in the drain hose to the sump which created a large vacuum leak. The CCV valve body may have been functioning well enough to avoid driveability symptoms if the drain hose hadn't failed.

The 8 inch vacuum by your engine is a failure vs the specs of 4 - 6 inches. I conclude your CCV is failing but not so badly as to generate driveability symptoms. FWIW, if this were my car I'd continue to drive it but check vacuum regularly and have new CCV parts on hand. My logic being that although out of spec, the 8 inches of vacuum is still so weak that it is very unlikely to generate any other problems. And I don't know what I'd consider too much vacuum to tolerate; probably 12 inches (2 times upper spec) but that is an absolute double X triple WAG - not a SWAG since there is no science behind it. Or maybe I'd just wait for a nice day, replace the darn thing and be done with it.

I've never been able to understand the physics behind the blow for bubbles test. And I never got bubbling: not with 9 inches vacuum, not after my CCV failed entirely (but then it wouldn't with a hole in the drain hose) and not after CCV replacement with vacuum in spec.

Consider that with the vent hose disconnected from the valve cover and blowing into it, the chamber in the CCV is at atmospheric pressure or slightly above; certainly no vacuum. Therefore the CCV's diaphram and orifice will be wide open, ready to draw vacuum on the vent hose (and thus crankcase, if connected) as soon as the engine is started and inlet manifold vacuum is present. The air being blown into the vent hose will take the easy route to the inlet manifold rather than the path down into the sump to make bubbles. It seems to me that the only way to get bubbling would be for the diaphram to be failed closed or the distribution piece on the manifold to be clogged. In this case one would have +ve pressure with the engine running - a definite CCV failure. Yet a pass for a good CCV is supposed to be a little resistance and bubbling when blowing into the vent hose.

Originally Posted by ztom

I think some of the posts are incorrect. The vac hose effect is to reduce rail pressure at idle, by increasing bypass fuel flow. The cases where hose is tied to cvv may have additional effect to increase rail pressure at high rpm.

You're correct that my explanation is wrong or at very least incomplete. I checked TIS and the M52 engine does adjust fuel pressure depending inlet manifold vacuum. The M54 engine does not; it uses constant fuel pressure.

However, based on pictures and diagrams I've seen, the connection point on the CCV should be at crankcase vacuum, which is a constant 10 to 15 millibar vacuum. Essentially atmospheric; nothing like the 700 to 900 millibar inlet manifold vacuum seen during idle or over-run. So I can't explain the connection and response by the fuel pressure regulator.

I regret posting the mis-information on this question. I hope that someone else can provide an accurate explanation.

Originally Posted by rdl

Two years ago, my car failed vacuum at 9 inches but had no symptoms at all

Interesting. Where did you check the vacuum from? I placed my clear hose over the dipstick.

I have been meaning to doublecheck mine again just to make sure I didn't do it incorrectly so if there are other places to doublecheck the vacuum, that would be useful as a check of my procedure.

Originally Posted by rdl

A couple of months later ... the engine then refused to idle, generated a raft of DTCs and lit up the CEL.

I had that exact problem just a few months ago:
- Does the ORDER of pcodes listed in an OBDII scanner actually matter?

A smoke test implicated the lower vent hose to the CCV, which, like yours, was holed (in fact, it was nearly broken in half!).

Originally Posted by rdl

Even after failure, I had no smoke.

Even with that holed CCV hose, I also experienced no smoke. But there were tons of lean-misfire codes!

Originally Posted by rdl

I conclude your CCV is failing but not so badly as to generate driveability symptoms.

I don't disagree. Plus, the CCV is definitely original, so it's a decade old at this point in time.

Originally Posted by rdl

I'd continue to drive it but check vacuum regularly and have new CCV parts on hand.

I understand that logic. That's what I did with my cooling system. The CCV, even for you guys, is a pain. So just imagine how time consuming it will be for me!

Originally Posted by rdl

I've never been able to understand the physics behind the blow for bubbles test.

Me neither. I don't personally think it tests anything. I said so in the aforementioned CCV test thread but I'll append your deduction also so as to add weight to the premise.

My comments in red font

Originally Posted by bluebee

Interesting. Where did you check the vacuum from? I placed my clear hose over the dipstick.

I checked via the dipstick tube.

I have been meaning to doublecheck mine again just to make sure I didn't do it incorrectly so if there are other places to doublecheck the vacuum, that would be useful as a check of my procedure.

The only practical option that comes to mind is the oil filler. Either drill out a cap and fit a hose barb or a fabricate a flat plate with gasket surface and hose barb.



I had that exact problem just a few months ago:

I wound up a boatload of lean related codes too.
I think that what happened is that the CCV was failing vacuum but without any driveability problems. But the hose was still intact or only very slightly holed. When the hose failed for good a few months later, the vacuum leak caused all the driveability symptoms and DTCs. I wish that I had checked crankcase vacuum then; I'm almost certain that it would have been zero at that point. I suspect I could have gone a several more months (at least until warmer weather) without any problems if the drain hose had not failed.


- Does the ORDER of pcodes listed in an OBDII scanner actually matter?

A smoke test implicated the lower vent hose to the CCV, which, like yours, was holed (in fact, it was nearly broken in half!).
... image deleted ...


Even with that holed CCV hose, I also experienced no smoke. But there were tons of lean-misfire codes!


I don't disagree. Plus, the CCV is definitely original, so it's a decade old at this point in time.

Old doesn't necessarily mean defective. But with plastic ...


I understand that logic. That's what I did with my cooling system. The CCV, even for you guys, is a pain. So just imagine how time consuming it will be for me!

The CCV renewal is certainly a few hours but straightforward, not so difficult except for the infamous S tube to the CCV valve. Most people report spending a LOT of time on this connection. I did, IIRC over an hour before the light bulb came on. There is a solution,
http://www.bimmerfest.com/forums/sho...7&postcount=77
see post 77 in Fudman's DIY.




Me neither. I don't personally think it tests anything. I said so in the aforementioned CCV test thread but I'll append your deduction also so as to add weight to the premise.

Originally Posted by gary@germanautosolutions

Steve,

It looks like both pictures that you uploaded are the same.

I'm still a little confused as to whether you agree with me and RDL on how the system functions, or if you are still taking an opposing view. I'm not trying to be sarcastic in any way, I'm just not sure if we are on the same page yet.

Thanks,

Gary

Sorry for the late reply - I just looked at this thread again.

Indeed I posted the same photo twice. I've posted the second photo below. It shows a section through the M54 oil separator part of the CCV.

I doubt this adds anything to the current discussion, but I wanted to post it for completeness.