Excessive CCV or Engine Blowby

geordi · **Posted:** Thu Oct 30, 2014 12:21 pm

I've stayed clear of the vacuum discussion from GMCTD for a while, wanting to try and understand the place he is coming from.

HOWEVER, just this one thing keeps bothering me: I have pulled the factory CCV puck apart. There is a rubber flap and a spring in the center, and this is the problem - Under strong vacuum from the turbo, the flap will overpower the spring and BE PULLED CLOSED, trapping the pressure in the engine.

Am I remembering the design wrong? If not... How do you account for this in all your vacuum / pressure discussions?
In all things, this is an arse-backward design.

I had an EHM, and towed. I did NOT have any seal or head gasket or overheating issues. My bottom end bearings failed on two different engines, for reasons that escape understanding on the second motor. I would love to point to such a simple thing as the EHM as the cause, but I seriously doubt that is the case.

WWDiesel · **Posted:** Thu Oct 30, 2014 1:10 pm

I totally agree with you, the more I dug into this, the muddier the water got so to speak. :banghead:

I have been running a EHM for well over a year now with only the normal smoking at idle out the EHM pipe. So I finely decided to purchase the ProVent and was very curious as to how it best needs to be plumbed, vented to atmosphere or connect it back to the turbo intake pipe. Based on the feedback, it looks like the ProVent has to be connected to the turbo inlet pipe to function properly? :roll:

This is a strange little engine with some very quirky little requirements that we all are trying to fully understand. Its requirements are much different than what we were brought up with and what some of us have worked on in the past!

This has been a very good discussion on this aspect so far with a lot of information by all to consider and it is appreciated!!
That is why this site is so GREAT, open, honest, discussion, we all learn! :wink:

gmctd · **Posted:** Thu Oct 30, 2014 3:16 pm

Under normal conditions, pressure will always be available in closed crankcase system - crankase pressure will rise to assist spring under over-vacuum situation thru passage designed for just such situation, balancing the 'opposing' forces - that diaphragm valve is intended to limit vacuum under high-boost conditions, when compressor inlet depression is high, also if vacuum increases in intake tract when air filter is extremely clogged

Lemmesee if I can find puck functional description...................

gmctd · **Posted:** Thu Oct 30, 2014 5:54 pm

And, again, I return empty-handed - I had aparted the CCV for cleaning way back when, and posted a description of functional operation, but it's apparently now somewhere in the ozone layer .......................

See: Oh, yeah!?!?!? I gotcher puck right here....................

Almost fergot - where I'm coming from is a Federally-mandated EPA emissions-compliance inspection sticker state - you can't put no junk on the hiway -

No tickee - no drivee.............

Deleted for photo shoot, with corrections

geordi · **Posted:** Thu Oct 30, 2014 7:29 pm

Ok, so the fracking-filled state of Texas wants to ensure that only oil companies can pollute the state, and you can't have an open EHM exposed on the engine. Fine, I didn't like the smell from it anyway. Once the EGR is capped off, the oil mist into the intake does nothing to harm anything anyway, provided you have Mishimoto or Samco hoses.

BUT, back to the CCV design.

The two ports into the valve cover aren't for "oil drain back" they are for venting both sides of the valve runners where the pressure is coming from in the first place. Since the valve cover sits directly on the center of the head, the driver's side needs a way to be evacuated too. I suspect that the intake side shows less oil contamination (through the connecting passage in the valve cover, visible when the CCV is removed - one of the ports is shallow, not an open hole) much of the pressure and oil spray is actually from the exhaust side, with the pressure coming from peak cylinder pressure following the valve shaft as soon as it opens to the exhaust manifold.

If I remember correctly about the design of the puck, both entrances connect around the outside of the central chamber, which has the small outlet hole to the exit port. If the vacuum is sufficient on the center to suck the flap closed - I do not believe that there will be sufficient pressure just around the edges of the diaphragm to force the center to release! Vacuum motors (such as the VNT controller) are very strong and can fully retain their "closed" position with minimal vacuum... They have to WANT to be released. This spring wasn't very strong at all in my CCV, so I still believe that if the turbo suction is sufficient, that flap will slam closed and stay that way, until the crankcase pressure is far exceeding the tolerances of other components.

Backpressure within the valve cover also would never have enough pressure or vacuum to alter the performance of the valve springs - I don't believe that should even enter consideration here. We are talking normal pressures less than 5psi, and for anyone to lose a rear main seal from lack of CCV flow... I suspect that their crank case pressure would be FAR exceeding that level, most likely due (and has happened) to a frozen-plugged EHM hose. THAT is a proven failure point, I haven't heard of anyone with any kind of failure with just the CCV or even a Provent - But the overall operational success of either is subject to debate.

There is a device for the VW TDI crowd that I had on my first TDI engine - I believe it was referred to as the Old Navy CCV Puck and was a very finely-designed aluminum housing that would plug in to the CCV port on the cover, and had a donut of white wool-like filter material. The same stuff you can buy in the auto store for normal CCV traps on older cars. There was an aluminum cap and o-ring that spun into place on top, and then the regular output hose could connect it back to the intake.

What this did, (and did VERY WELL) was to supply a physical barrier to airborne-oil-mist that would capture the oil, and allow it to naturally drain back to the valve cover. Sounds like a Provent, eh?

It worked great. Maybe all we need is something like that, there is certainly more than enough room within the engine bay on top of the CCV for something 1-2 inches taller than the CCV puck itself, so that could allow for quite a large amount of filter media, which could solve this whole problem in a nice pretty billet-aluminum method and retain the hose to the turbo intake to keep the various enviro-nazi inspectors happy... While they ignore the REAL polluters out there.

gmctd · **Posted:** Thu Oct 30, 2014 8:52 pm

Remember, here, that the CCV puck is called an "oil separator" in the FSM, and that it was designed for a normally-aspirated CRD - the turbo was added later for the KJ and etc, completely over-whelming the device - the large diaphragm was to allow the slight vacuum resulted from normal clean air filter restriction, measured in "H2O, to control the device against crankcase effluent pressure, and vise versa (and do I ever like my vice versa!)

The compressor intake is capable of increased depression, or vacuum, but nowhere near the vacuum from the vane-type pump in the crankcase, which can produce at least 20"hg - vacuum at compressor inlet is also measured in "H2O, and can produce greater values than the naturally-aspirated version -

27"H2O = 1"HG
2"HG = 1psi
30"HG = 15psi BARO
-30"HG (or 30"HG vacuum) = 0psi BARO
15psi BARO = ~470"H2O

Figger the area of a 1" diameter circle, which the exhaust port is one of, then do the same for a 3" diameter circle, which the puck diaphragm is one of - when the diaphragm closes the exhaust port, BARO (15psi) pressing downward only affects the area of the diaphragm above depressed area inside the exhaust port - the larger diameter is not exposed to the sealed vacuum, so external BARO is not in play, allowing the larger diameter area to respond to crankcase effluent

geordi · **Posted:** Thu Oct 30, 2014 11:08 pm

Performance of the vane vacuum pump is only that effective because it is a closed system. It is sucking against zero vent sources until the brake is pumped or the turbo is told by the solenoid to open the vanes, which lets fresh air into the vac motor. Any suction in a closed system will quickly hit 20 inches of mercury.

The thing is - The turbo is more than capable of producing 15psi above ambient, which in your numbering should then equate to -30 inches mercury. The surface area of the turbo is HUGE compared to the vac pump, and the suction is sufficient to DOUBLE the air volume within the intake plumbing, and then some. It is easy to think that there is enough suction behind the air filter to evacuate just 2 inches mercury.

Yes, there is a substantial amount of that air coming from the air filter, HOWEVER, the path of least resistance includes the air that is already behind the filter, and coming at the turbo with a slight positive pressure. The turbo's suction should then evacuate the current crankcase pressure, and upon zeroing the crankcase, vacuum will be reached, and the puck should slam shut. At that point... If you are continuing at high boost, why would that puck ever open again until you let off the loud pedal? Boost will be continuous, ergo suction on the back of the air filter will as well - any pressure building in the intake will have no place to go. For long-distance high speed towing at 15psi or greater... This thought process doesn't please me at all. The crankcase pressure needs to have someplace to go, always.

If as you suggest, the CCV design was based on a non-turbo engine... Then we need to think about removal of that flapper and let the crankcase operate at a negative pressure all the time. I cannot see any downside to that, as the smell will be contained, the seals will be protected, and yet another poor design choice from VM (being messed with by DC) can be eliminated from the list of potential problems. Whether that flow passes through a provent or just a pad of filter material... I don't care - but the pressure HAS to have a place to go.

gmctd · **Posted:** Thu Oct 30, 2014 11:48 pm

The vacuum pump is depressing a closed system - the turbo is pumping an open dynamic pass-thru system - no way will a tap in the intake duct produce high levels of vacuum - the constantly in-flowing BARO input guarantees that, feeding a 'nuther positive-displacement type pump known as an engine - again, the depression is low enuff to be measured in inches on the water column "H2O - it is, after all, only slightly below barometric pressure - 'nuther words, even tho showing vacuum, there is still more atmospheric pressure than vacuum

If you want to see higher levels of vacuum in the compressor inlet, pull the duct and place a steel cover over the inlet - still won't produce very high levels because it is not positive-displacement, meaning that the output can bypass back to the input thru the clearance between the vanes and the scroll - positive-displacement pumps such as vane, diaphragm, and piston-type can produce high levels of vacuum, measured in inches on the mercury column "HG

Since engine output is not always at full Boost, the diaphragm will react to varying Boost levels as well as crankcase pressure levels

I would like to imagine that the puck's response to increased vacuum levels was addressed in engineering, maybe by increasing spring tension or reducing diaphragm conformance by increasing thickness, or both - but the effective rework should maybe have included an 8" tall puck chamber for increased centrifugal slingout and a poly or fiberglass coalescing filter, or the simple addition of the EPA-approved PROVENT cannister - whatever was or was not done on the production line, defeating the system will not suffice in an EPA-regulated state

I did extensive instrument testing when building my GM 6.5TD, with pressure, vacuum, temperature gages everywhere - that datum is on one of my hard drives somewhere - if I can find it, I will post compressor inlet vacuum levels vs output pressure levels with temperature data - I had pre- and post- measurements on the compressor, the charge-air cooler, the intake plenum, the exhaust manifold, the turbine outlet, and ~ 3 feet down the down-pipe

flash7210 · **Posted:** Fri Oct 31, 2014 7:50 am

So is EHM bad or is EHM good?
I just dont see how the EHM could do any harm unless you live somewhere where it gets cold enough to freeze up.

I'm not against the Provent. I just dont want to pay for one.
I made my own provent like thingy and it worked reasonably well.
It trapped some of the oil from the CCV but not all.
And I noticed some leaks around the hose fittings so I'm sure it never maintained a vacuum.
But after my intake hose deteriorated and ripped apart I went to staight EHM.

gmctd · **Posted:** Fri Oct 31, 2014 11:39 am

Long ago and far away, in another time and another century, all vehicles propelled by infernal-combustion engines had elephant hoses - in the '70's federal government stepped in and outlawed all EHM 's butcept on commercial heavy-duty vehicles, where 2500, 3500 and up gvw trucks were exempted - GM's Diesel lineup included the 1500 series, so their entire 6.5l lineup was subjected to EPA restrictions across the board - DODGE and FORD wisley rated their Diesel lineup as 2500 and above, so they were exempted - 1997 new DODGE RAM 24v CUMMINS got a modified EHM with an oem-installed catch-can with filter - by ought 3 that catch-can had disappeared because all infernal-combustion engines, gasoline-fueled AND Diesel-fueled, were required to meet 2002 EPA regulations which now even includes motorcycles, motorscooters, inboard motors, outboard motors, lawnmowers, weedeaters, chainsaws, generators, etc - you may notice a warning label on some devices as not for sale in Kalifornia: those devices may have begun conformance but are not fully EPA-compliant, thus are not even available therein.

Even if I tho't it to be a good idea, WHICH I DO NOT, I would not advocate a return to the EHM concept due to residing in a federally-mandated fully EPA-compliant state - I enjoy driving my Diesel trucks on the federally-funded system of greatly-improved-over-most-other-states hiways and biways here in Tejas -

So, I endeavor to explain the advantages of maintaining compliance - it is not all bad.

Also, the walls have ears and eyes....... :grim:

...........

flash7210 · **Posted:** Fri Oct 31, 2014 11:59 am

Quote:

Even if I tho't it to be a good idea, WHICH I DO NOT, I would not advocate a return to the EHM concept due to residing in a federally-mandated fully EPA compliant state - I enjoy driving my Diesel trucks on the federally-funded system of greatly-improved-over-most-other-states hiways and biways here in Tejas -

Yeah, yeah... EPA... blah, blah...

From a technical aspect, for good engine running and stuff. Lets say I resided in Mexico and only drove on Mexican roads. Is the EHM a good idea or not?
Cause, you know, I might move there when I retire.
Or maybe Uraguay. I haven't decided.

gmctd · **Posted:** Fri Oct 31, 2014 12:05 pm

Move first, for my then-appropriate response............... :goink:

flash7210 · **Posted:** Fri Oct 31, 2014 12:13 pm

Awww. You're no fun.

gmctd · **Posted:** Fri Oct 31, 2014 12:46 pm

Actually, the EHM is a not good idea - I have seen many engines from that era totally destroyed, with scratching\scarring of the crank journals, cam journals and lobes, cylinder walls, oil pumps, etc - these engines were from farm-rated vehicles, field-service vehicles, etc, subjected to constantly-dusty conditions encountered in those scenarios

For an EHM to function correctly(?), it must be plumbed down to a low-pressure area below the engine, with corresponding mesh-filtered breather-cap somewhere high on the engine: valve-cover, cam cover, oil filler tube, etc - the EHM also had a mesh filter at the top, sometimes inside the port in the engine

The area beneath the vehicle is constantly subjected to huge volumes of road dust, off-road dust, field dust, etc dust, requiring scheduled filter-service, top and bottom

Operators\owners eventually ignored service schedules, such that the filters would become dirt, grime, and carbon-caked - the EHM mesh would eventually be discarded upon noticing excess vapors thru the breather-cap, which was also becoming plugged but less noticeable after EHM mesh was removed - no vapors = problem solved

Now for the major problem with the EHM: upon deceleration, where engine compression is used to slow the vehicle, crankcase can become depressed below BARO pressure, such that air is 'sucked' up thru the EHM and into the crankcase, contaminating engine oil: dirty dust-laden air from below the vehicle - most SAE engineers seem to agree that this is not good for an engine, gasoline or Diesel - having seen engine damage resulted from these scenarios, I tend to agree with them

So, even in Paraguay, I could not advocate EHM conversion -

Filter schedules are way more important on a Diesel engine than a gasoline-fuel version - notice the installed FILTER-MINDER on my airbox, shown in the picture - it responds much sooner in dusty conditions than in normal on-road contitions

flash7210 · **Posted:** Fri Oct 31, 2014 12:59 pm

Thank you.
That was such a pleasant, convincing, and easy to read response that I will go right out and re connect my CCV hose to its proper location.

Yes, Paraguay is possible too. But not for permanent residence. Just a staging area before invasion and conquering of Uraguay. :mrgreen:

WWDiesel · **Posted:** Fri Oct 31, 2014 1:06 pm

To add little more information to digest on this matter: :roll:

CCV = Closed Crankcase Ventilation (CLOSED system aka connected to turbo inlet pipe OEM)
OCV = Open Crankcase Ventilation (OPEN system aka EHM)
I added the mbar to psig conversion for those who relate more to that measurement! :wink:

Information by Mann & Hummel on the operation of their ProVent oil separator...
Generation of blow-by gases:
For every piston stroke in a combustion engine, there are exhaust gases, which flow between the piston rings and sleeves. These gases enter into the crankcase. In turbocharged engine applications, air can also make its way into the crankcase through the oil return pipe of the turbocharger. These gases are generally called blow-by gases. The pressure they create lead to an unacceptable pressure build-up and crankcase ventilation becomes necessary.

In many countries, regulations governing car emissions stipulate that the crankcase ventilation must not enter the atmosphere. That is the reason why blow-by gases from car engines are redirected by so-called closed crankcase ventilation to the intake pipe assembly and burned. The open systems (without a cleaning process) direct the oily blow-by gases through a pipe into the atmosphere exposing the environment to all the undesirable gases and their detrimental environmental effects.

Pressure Regulation:
Pressure Regulator (located on the outlet of the ProVent)
In closed systems the pressure regulator can be set as required while keeping the crankcase pressure independent from the negative pressure of the air intake manifold. Setting the pressure level simply depends on the quantity of blow-by gases
The crankcase pressure remains within a narrow range even with variable air flow rate, negative pressure and varying blow-by gas volumes. In open crankcase operation, the pressure regulator of the ProVent is not in operation. The outlet port simply vents to the atmosphere. In this configuration there is a slight excess pressure in the crankcase.

So bottom line, it looks like the pressure regulator on the ProVent helps the VM puck on top of the engine to keep the pressure, or negative pressure, inside the motor in a narrow range of operation?????
:roll:

gmctd · **Posted:** Fri Oct 31, 2014 1:19 pm

FYI, my engine source thru-out the years purchased warranted\damaged engines in large quantities from local dealerships -Tejas being a big-oil state, the oil companies and petro-chemical service companies purchased vehicles in quantity for field service operations - thus, my exposure to various and sundry types of engine failure, including newer in-warranty vehicles - it could soon be learned what would\will and would\will not survive, including the causitive scenario which resulted in any abnormal failure - such as a DIESEL in an oil field with a methane\H2S leak, where the running engine suddenly revs to max rpm which cannot be stopped by turning the IGN off, dis-connecting the battery, etc - everybody runs away, leaving the engine to it's own machinations - result: brand-new Diesel engine with all accessories = $500.00

Similar pricing for new GM 350's, 400's, 427's, 454's, etc, as required - those were the good ole days, long ago and far away......................

greiswig · **Posted:** Fri Oct 31, 2014 1:32 pm

All of this is pretty interesting, really. But...

Again, I'd like to hear if anyone seems to have suffered seal failures or head gasket failures, and if we have enough data to figure out whether those are really correlated well with EHM mods?

The one assertion that extreme cases of crankcase pressures could lead to head gasket failures, in particular, is really interesting to me: how could that possibly be so? How could any realistic level of pressure in the crankcase begin to compete with the cylinder pressures?

But if this is what is happening, maybe folks driving around with EHM modifications are also disproportionately the same ones who are suffering from HG failures, and are inadvertently bringing it on themselves. But I'd like to know how.

WWDiesel · **Posted:** Fri Oct 31, 2014 2:41 pm

greiswig wrote:

All of this is pretty interesting, really. But...
Again, I'd like to hear if anyone seems to have suffered seal failures or head gasket failures, and if we have enough data to figure out whether those are really correlated well with EHM mods?
The one assertion that extreme cases of crankcase pressures could lead to head gasket failures, in particular, is really interesting to me: how could that possibly be so? How could any realistic level of pressure in the crankcase begin to compete with the cylinder pressures?
But if this is what is happening, maybe folks driving around with EHM modifications are also disproportionately the same ones who are suffering from HG failures, and are inadvertently bringing it on themselves. But I'd like to know how.

I share your pain brother, and that is why I started this thread to hopefully get to the bottom of this with the correct answers.
It appears either extreme, pressure or vacuum on the crankcase is bad, high pressure will possibly blow out seals, and high vacuum will suck in air, dirt, etc... Based so far on all the data, it looks like the crankcase pressure should be kept in a very narrow band between +10 to -10 millibars through all ranges of engine operation.
I too like you have a hard time buying the head gasket failure part, a little had to swallow! That was a Racor statement and may have been a scare statement to get people to buy their product?? Just a guess!

Been running the EHM for about a year and 1/2 now and then decided to add a homemade filter to stop the smoking out the EHM when stopped. I had several people tell me when I was stopped, hey your car is smoking underneath! :ROTFL:

Have not had any HG problems so far and hope I don't! :wink:

So, I am installing the ProVent 200 today and connecting it back up to the OEM turbo inlet pipe connection. This seems to me to be the best and safest option all the way around for me. Stops the smoking under the Jeep and will keep the crankcase pressures within the narrow prescribed operating range and filter, trap any oil so it can be drained at intervals.

Anyone got any better ideas, I think we would all love to hear them!!!! :idea:

In the end, everyone still has to make their own decisions for what they feel is best or safe for their CRD...
Remember, you are your own warranty provider!

And thanks again, for all the great contributors to this thread, in the end we are all a lot more educated on this aspect of our little VMI motors....

gmctd · **Posted:** Fri Oct 31, 2014 2:45 pm

A brief dissertation on the turbocharger is required at this point -

The turbocharger is an exhaust-gas driven turbine-powered air compressor - the exhaust turbine drives the compressor fan via a highly polished
shaft, all rotating components assembled and precision balanced for operation at ~80,000 to ~200,000 rpm

The unusual aspect of this compressor is that in usual form it uses two aluminum bushing-type bearings - you read that correctly: sleeve-type
bushings in full-floating configuration - meaning the shaft freely rotates in the bushing and the bushing freely rotates in the bearing bore

This is the only method which will allow the extremely-high rotational speeds required to produce the volume of air at the required pressures,
from such a small device that uses sleeve-bushing bearings

You may have noticed the woven stainless steel hose connected to the top of the cartridge, which is the casting which carries the turbine
wheel, drive shaft, compressor fan, and bearings - this is a piece of thin teflon tubing, which can survive temperatures up to ~550*F, but
which could not withstand very high pressure - the woven ss braided shield handles the pressures, while protecting the thin inner tubing from
cuts, abrasions, and other damage - this supplys oil at engine pressure to the bearings

The cast-iron cartridge bearing bore is polished, the turbine shaft is polished, but the bearings have natural aluminum finish - there is a
groove cut around the center of the bearing, with 4-6-8 bored holes - pressurized engine oil is supplied thru a y-passage to each bore, then
into the groove, thence to the shaft thru the holes - thence into a large gallery below the bearings, and back to the oil-pan thru a large
15mm dia ss tube connected to the crankcase - the large bore in the crankcase for this drain tube can be seen in my PROVENT install pic

The turbine shaft spins at 100,000rpm inside the bearing bore, the bearing spins at 50,000rpm in the cartridge bore, each separated and riding
on a film of pressurized engine oil - the shaft doesn't contact the bearing, the bearing doesn't contact the cartridge bore

Liquid engine oil enters the bearing area in the cartridge, but what comes out is unrecognizeable as engine oil - in appearance and density, it
resembles the thick golden froth on those expensive cups of coffee, having been whipped up by the unequal spinning of the bearings and the shaft -
this thick froth would not drain thru a normal tube like the oil-supply tube, so a large diameter return tube is required to evacuate the large
gallery under the bearings

It can be seen, then, that any opportunity for air to enter the crankcase thru the turbo drain tube is almost non-existant - almost,
because a severly-worn compressor-end bearing could leak pressurized air to the center-cartridge gallery area

The turbine-end shaft gets a rotary ceramic seal due to the high heat encountered there, and a snap-ring in a groove which has a centrifugal effect

The compressor-end shaft gets no physical seal because scroll pressure prevents oil leak-by - any oil that does get thru as the bearing wears
encounters a centrifugal area in the scroll shaft-bore which returns the oil to the bearing

A severely worn compressor-end bearing could leak air, but the wear would be readily noticed by the driver due to reduced Boost output, as
the mismatched shaft\bearing\bore would reduce available shaft speed and compressor output - bearing wear would increase rapidly as Boost blew all lubricating oil out of the bearing

However, under such event, the PROVENT could handle the crankcase effluent, as described.............

Excessive CCV or Engine Blowby

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