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Discussion Starter · #1 ·
I just came across this interesting little trick for diagnosing blocked CCV in the Volvo forum:

With the oil cap sealed, engine on, stick a balloon over the dipstick tube and see if it inflates. If it inflates you need to service the PCV system.

...Lee


I think he meant with the dipstick removed, so the balloon goes over the dipstick housing.

No balloon, no problem, get an old dish washing glove, cut a "finger" off and tie it with rubber band.

http://www.matthewsvolvosite.com/forums/viewtopic.php?f=1&t=28322
 

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Any pressure will become evident as soon as the engine is turned on--what they are pointing to, is that
the pressure to just partially inflate the balloon is evidence the pvc system needs work.
I would guess that when trying this procedure on our cars--if the ballon trys to be sucked into the
dipstick hole just a little that all is OK--if it's being sucked in at a high rate though the ccv could be going bad.
 

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On the VANOS repair site (Rajaie) posted this trick

"The crankcase vent valve and 4 associate hoses fail and cause a vacuum leak. The valve gets stuck open and the hoses crack. These last 70-120k miles and usually fail 80-90k miles. Here are a couple diagnoses.
At warm idle, place a small plastic freezer storage bag on its side over the oil fill hole. If the bag sits on top or gets slightly sucked in, ~1***8221;, the valve is good. If the bag gets significantly sucked in the hole the valve is stuck open and bad.
With the engine off and cold, carefully remove the hose at the valve cover front corner. Blow hard into the hole. You should hear oil bubbling in the oil pan. If you don***8217;t hear the bubbling the top or bottom hose is likely cracked. The bottom hose often breaks just below the valve connection. There can also be cracks in the other two hoses."
 

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Discussion Starter · #5 ·
..if the ballon trys to be sucked into the
dipstick hole just a little that all is OK--if it's being sucked in at a high rate though the ccv could be going bad.
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.
 

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Not sure who is right here but Gtxragtop (Dave) did a test on my dipstick tube to determine CCV function by measuring the amount of vacuum pulled (I can't remember but I think the proper amount is 3"-6" of water). Not sure where this test came from (TIS?). No/low vacuum meant a CCV problem. My understanding is this test measures the amount of vacuum in the crankcase. But I am not sure how the pressure in the sump translates to the pressure in the crankcase. According to this test, the sump should have negative pressure and pull on the balloon, if the CCV is functioning properly. If it inflates the balloon, there is definitely a problem as that would indicate positive pressure in the sump. In addition, positive pressure in the sump should also blow the dipstick out of the hole. In theory the CCV is supposed to keep the crankcase from a positive pressure condition and that a failed CCV will create a positive pressure situation by keeping the crankcase from venting gases. If I sound confused, it is because I am. :dunno: All I know is that I replaced the damn thing and I have stopped burning oil.
 

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Discussion Starter · #7 ·
In a nutshell, the crankcase always produces pressure from blow-by. The CCV is simply a "middleman" controlled by Intake Manifold Vacuum.
This way the positive pressure from the crankcase is removed by the CCV which separates oil and vapor:
- Oil goes back down the crankcase
- Vapor goes back into the Intake manifold.

This is why the CCV is also called "Oil Separator" in the Volvo language.
 

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In a nutshell, the crankcase always produces pressure from blow-by. The CCV is simply a "middleman" controlled by Intake Manifold Vacuum.
This way the positive pressure from the crankcase is removed by the CCV which separates oil and vapor:
- Oil goes back down the crankcase
- Vapor goes back into the Intake manifold.

This is why the CCV is also called "Oil Separator" in the Volvo language.
Got most of that. Someone correct me if I am wrong. I refer to the real.oem diagram for the CCV. The oil and vapor from the cylinder head (positive pressure) goes into the CCV through the vent pipe (2). The CCV "separates" the liquid from the vapor and returns the vapor portion back into the intake manifold (negative pressure) using the connecting line (3) and the return pipe (7). The liquid oil condensate flows back into the sump via the vent hose (4).

If the previous is correct, is the sump at negative pressure, ambient or positive pressure? The dipstick vacuum pressure test suggests it is at negative pressure.

I ask because my previous e39 (which Gtxragtop tested) tested OK for negative pressure even though the car demonstrated some of the classic symptoms of CCV failure (oil consumption, burning oil, etc.). My current e39 appeared to burn oil (occasional black exhaust smoke in cold weather) but was never tested. I changed the CCV and that has gone away. It would be great to have a reliable test to verify proper CCV function as it is a PITA to change out. At this point, I am not so sure the dipstick vacuum test is that reliable of an indicator.
 

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Discussion Starter · #10 ·
Fudman,

The best way to look at this is:

1. "A" is the crank case pressure. It is the same whether you measure it at the Top Valve Cover Outlet or the Dipstick because the Top part of the Engine Cam Lobes area connect to the sump via some air channels (this is how crankcase air goes from the sump upward into the cam lobes area).

2. "B" is the Intake Manifold Vacuum.

The following numbers are arbitrary just to illustrate the concept.
Sea level air pressure is 760 mm Hg or 14.7 psi. But let's set this as zero as a point of reference purpose.

And let's say the CCV is designed such that when there is a differential of 3, it opens the spring allowing vapor to return to the I.M.

Scenario A: car warm and idling at 700 rpm:
- Atmospheric air "zero"
- Intake Manifold vacuum = "- 1"
- Crankcase Pressure: goes slowly from "1" to "3" (from blow-by)

At "-1" and "1", the difference is only 2, so the CCV is closed, but at -1 and 3, the difference is 4 so the CCV is open allowing vapor to return to the I.M. At the same time, liquid (oil) is allowed to flow back down the crankcase drop by drop (basically dripping, not a full flow).

Scenario B: you are driving at 3000 rpm:
- Atmospheric air "zero"
- Intake Manifold vacuum = "- 3"
- Crankcase Pressure: goes slowly from "3" to "5" (from blow-by)

In this case the CCV is always open because the min difference is still 6.



Maybe one of us can get a birthday balloon and play with it this weekend and report back (assuming your CCV is fine)?
 

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On the VANOS repair site (Rajaie) posted this trick

"The crankcase vent valve and 4 associate hoses fail and cause a vacuum leak. The valve gets stuck open and the hoses crack. These last 70-120k miles and usually fail 80-90k miles. Here are a couple diagnoses.
At warm idle, place a small plastic freezer storage bag on its side over the oil fill hole. If the bag sits on top or gets slightly sucked in, ~1", the valve is good. If the bag gets significantly sucked in the hole the valve is stuck open and bad.
With the engine off and cold, carefully remove the hose at the valve cover front corner. Blow hard into the hole. You should hear oil bubbling in the oil pan. If you don't hear the bubbling the top or bottom hose is likely cracked. The bottom hose often breaks just below the valve connection. There can also be cracks in the other two hoses."
This bag trick is messy on the 540i because the oil fill location is on top of the timing chain, which when the engine is running will whip oil through the oil fill hole. I think the ballon trick would be best for the V8's.
 

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CN90--don't know about you M52--but my M54 has always had vacuum at the dipstick as well as the valve cover oil cap--on the later engines there is a vacuum directed into the crankcase via the valvecover gasket
the oil dipstick tube has two different channels in it to allow oil to drainback and the dipstick itself.
One of the big problems that must be watched out for when doing the ccv valve work on the M54 engine
is to make sure the dipstick tube 0 ring is seated properly when doing the reinstall and ensureing there isn't a vac leak there. Vacuum is introduced into the crankcase from the distribution unit--then to the ccv and from there to the valve cover.
 

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The crankcase, valve cover, dipstick tube are all connected by wide open space. Remember, the oil on the camshaft has to drain back down to the sump. According to the TIS, the vacuum should be between 3-6" of WATER no Hg (mercury) which is the measurement used on a typical vacuum gauge. 3-6" of H2O is not very much. The goal of the CCV as others have stated is to maintain a slight vacuum under all conditions.
 

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The best way to look at this is ...
Hi Cam,
Looking at this diagram (to figure out how the CCV works), did I draw the directions of the pressure (orange) and vacuum (yellow) in the M54 engine correctly?

Notice you do not show the direction of the thin line called "vacuum hose", so I 'guessed' at which direction the flow is going.

Likewise, the Realoem diagram for my M54 engine seems to have the "return pipe" reversed, so, that adds a bit of confusion.

Can someone correct this diagram so that we have the correct directions for the M54 CCV?


 

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BB:

Your flow directions are correct except for the vacuum hose. The RealOEM parts diagram is INCORRECT. There is NO vacuum hose. When you remove your old CCV, you will see that the vacuum hose connector is capped and the new replacement CCV is also capped.
 

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Your flow directions are correct except for the vacuum hose. The RealOEM parts diagram is INCORRECT. There is NO vacuum hose.
Now that's interesting.

I realize YOU have the same M54 that I do, and that you already replaced your CCV, so you should know:
- DIY: CCV Replacement on an M54 & Replacement of the CCV on M54, both by Fudman

However, from reading all the DIYs, I do know 'some' CCV's have a black orange-striped vacuum hose:
- DIY: change of the CCV / Pressure regulating valve / oil separator, 99 528i, by aioros

So, the question is, if realoem is wrong, how do we know, ahead of time, WHICH ccv's have the vacuum hose and which don't?

 

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the M54 3.0 does not have this vacuum hose. I believe rdl's experience mirrors mine.
I have a M54B25 but I'll wager it's similar (since it's an M54).

Certainly Aioros' 99 528i has the (orange-striped) vacuum line connected to the CCV.

In 'that' case, which direction is the vacuum?

  • Is the vacuum in that line a 'result' of the huge (in comparison) lines connected directly to the intake manifold?
    • In which case, the arrows should point INTO the CCV
  • Or is the vacuum in that line a 'signal' to the CCV from some other vacuum source
    • In which case, the arrows should point AWAY from the CCV
 

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Based on Fudman's comments, I searched for RDL's comments and found where he also confirmed his 530i also does not have the orange-striped vacuum line that Aioros has on his 99 528i.
- CCV replacement tips

BTW, my M54 does not have pt# 6 "vacuum hose" although RealOEM indicates it is supposed to be present
Here is the realoem diagram for a 11/2001 production month 530i showing the vacuum hose that isn't there.

Of course, that realoem diagram also shows a #8 which isn't described; and it shows the #7 return pipe reversed ... so, it's not infallible!

 

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