'06 4.2L-Filthy oil inside air plenum.

[stvrob]

I was cleaning the throttle body in my '06, and noticed that the inside of the air plenum (directly on top of the engine, just upstream of the throttle body), was sprayed with creamy looking oil. Apparently the short tube which supplies clean air to the top of the engine has instead been supplying oily froth up into the plenum. At first I figured it might not be a problem, since there is no pcv valve on this engine, but the oil in the crankcase seems to be especially filthy lately. Also, when started cold, the engine surges and hunts for a proper idle rpm, sometimes rather violently so that I have to intervene with my foot on the throttle. And it keeps throwing a P0014 (camshaft position sensor). I have been attributing this to dirty oil, and I have removed and cleaned the camshaft position actuator several times thinking the little screens are plugged. Now Im thinking this might have nothing to do with the problem.

The engine is well worn, it has about 180,000 miles now.

Where is the dirty air supposed to be removed from the engine? I feel like I don't understand the proper flow of crankcase gasses in this engine.

 

[BlazingTrails]

You have a vacuum line going from the block to the intake manifold on the driver side of the engine. check to make sure that the pipe is not clogged. as far as the oil being frothy it sounds like you may need to test for a blown head gasket.

What is the maintenance history of the truck?

 

[stvrob]

You have a vacuum line going from the block to the intake manifold on the driver side of the engine. check to make sure that the pipe is not clogged. as far as the oil being frothy it sounds like you may need to test for a blown head gasket.

What is the maintenance history of the truck?

Maintenance history of the truck you say....? Well, Ive had it since 2007, so I would have to admit the maintenance has been rather sketchy. Ive done the best I could, but Ive had lots of challenging problems. I do keep the oil changed regular, and I don't recall it appearing so filthy in the past.

I will have to find that vacuum line tomorrow and see if it is clogged.

 

[mrrsm]

Originally I thought that this problem was caused by oil leaking from the OUTSIDE of the Valve Cover and then getting vacuumed back inside the Intake Manifold along the edges of the flattened "O" Rings ... But I was Mistaken. The Best Description of what actually causes this problem follows on next... with @AtlWrk 's explanation.

 

[AtlWrk]

Filtered air enters the valve cover from the intake resonator through the short tube you've seen. It flows down through the head, into the crank case and back up to the head where it exits through the vacuum line (short "L" shaped rubber hose under the intake manifold) BlazingTrails mentioned and into the intake manifold to be burned.

It's not uncommon to have some oil in the intake resonator due to the close connection between the resonator and the intake manifold. I've noticed this since I got my truck with 29k miles. Another thing to consider is that, while we don't have a PCV valve, there is a small orifice in the head gasket itself through which the PCV air is metered before it heads out and into the intake to be burned. Excessively dirty air/oil could clog this as well rendering the PCV system inoperative.

Pull the hose between the intake resonator and valve cover and make sure there's a nice strong vacuum and flow at the valve cover nipple. (Mine whistles at idle with the hose disconnected).

Might as well as do a compression check and make sure you're not getting excessive blowby fouling up your oil too.

 

[mrrsm]

EDIT:

On a second read of the above Resonator to Short Hose information... I just realized that we are talking about Two Different Hoses: (1) The one mentioned above ventilates the space between the inside of the Valve Cover and the top of the engine head & valve train.... and (2) The one that I am referring to that is Dead Center at the bottom of the Intake Manifold (NOT THE RESONATOR) and IT evacuates atmosphere under pressure via that short elbow hose connected from the lower crankcase... consequently any blow-by gases can be vacuumed inside the Intake Manifold close to the area where the Intake Ports are located inside the head and thereby, the vapors get ingested and burned instead of escaping as noxious pollution.

Perhaps it contains enough crankcase oil in THAT vapor to settle on the inside the Intake Manifold adjacent the lower flange attachment points and THAT is where the oil is coming from... So instead of ONE PCV Valve and Routing Hose like in most other vehicles coming out of a valve cover and being routed back into the Intake Manifold... the Atlas Motor has TWO of them...ergo... Oil invading both the Resonator AND the Intake Manifold... But coming in from two different sources and locations!

If the Second Hose I just mentioned above is damaged , the top four frames from my Photobucket show the OEM Hose with the AC-Delco Part Number(s):

http://s557.photobucket.com/user/60...NEREPAIR/TRAILBLAZERENGINEPARTS?sort=3&page=5

 

[stvrob]

In a strange combination of problems... if the Valve Cover Gasket is worn and leaking on the Intake Manifold side of the engine head... AND the bolts holding the Intake Manifold onto the engine head are LOOSE... then gravity dripping oil can be INHALED at each of the six cylinders if the Intake manifold is uniformly loose across the entire length of the Engine Head. During each Intake Stroke, the partial vacuum will cause the free oil to be DRAWN BACK INSIDE THE ENGINE to enter the column of air going into each cylinder.

The swirl of this unfiltered atmospheric Dirty Air will enter the head and then Bake into a Black Muck... just inside the Intake Ports ...basically being cooked by the residual engine head heat as the valves open and close. Changing the Intake Engine Head Valve Cover Gasket(s) (meaning the ones around the COP-Spark Plug Hole locations, too) will stanch the loss of oil... and tightening the Intake Manifold Bolts will eliminate the vacuum draw that has been "Dirtying Things Up" inside the Intake Manifold Chamber. Doing BOTH of these actions will stop the Mysterious Oil Consumption Problem... Dead in its Tracks.

Here is a More Precise Description of How This Problem Occurs:

The reason this is possible is because unlike a Standard In-Line 6 Cylinder Engine with a Cast Iron Intake Manifold that is classically hard mounted with 3/8" Steel Bolts using a fairly solid gasket with the Carburetor sitting Vertically and the the intake air stream being vertical... The Atlas I-6 Engine has a Plastic Semicircular "Off to the Side" arrangement that, while certainly much lighter than a Solid Cast Iron Intake Manifold... Does NOT employ a very solid method of attachment to the Driver's Side of the Engine Block.

This problem is compounded by the use of compressible "O-Rings" that are constantly being squeezed and released while being subjected to the pendulum like action of the heavy- Side-Mounted Aluminum, Brass and Copper Coils-Throttle Body Motor Hardware, as it attempts to bounce up and down over the many dynamic up and down motions of the SUV. In time... these "O-Rings" tend to flatten out and get crushed... and then the Small Bolts holding the Plastic Manifold against the Engine Head can loosen so much... that you can unscrew them with your bare fingertips!

During the enormous numbers of Up and Down Bouncing Actions... as the Intake Strokes occur... if the Six Oblong Shaped Gaskets of the IM are VERY loose... then the vacuum of the Descending Pistons will be strong enough to suck in external air right along with any nearby dripping oil around each gasket...and literally vacuum the stuff BACK INSIDE THE INTAKE PORTS. And so... a good portion of the Leaking Oil... will NEVER make it far enough down the engine block to leak down to the ground and provide a clue that there is a Valve Cover Gasket Leaking Engine Oil.

This sounds like a nightmare! How likely is this scenario?

 

[mrrsm]

Well... the job of getting to ALL of the bolts holding on the Intake Manifold can be made a lot easier if you remove the Driver's Side Frame Brace/Battery Hold Down Bracket and remove the Battery to allow more freedom of movement if you go over the top of the engine to access the entire length of the IM. The alternative "By the Book" method is to elevate and safely Jack-Stand the front of the vehicle.. then pull the front wheel on the Driver's Side and clean the plastic wheel well cowling above the tire...then... Duct Tape the "Engine Access Panel Flap" up and out of your field of view... (This should work well for you... but it brings back very bad memories for me for other reasons).

I think that if you are going to be able to do the job right... the Engine Head Valve Cover and the Intake manifold deserve to be R&C&R'd ...(Removed and Cleaned and Replaced)...with a thorough cleaning before installing the new gaskets to both components. These are the kinds of jobs that reward the Thoughtful Mechanic who plans how to do everything well in advance and works out an approach on paper for all the necessary parts, procedures and access...and so forth...well before diving in to do any of this work.

If you find that your Intake manifold is either cracked, warped...Oily AND Sandy or Dirty inside and you decide to upgrade the manifold via Amazon.com, have a look at this information about the Dorman upgraded flavor of this item before using an older, stock OEM version:

The only other places in the Intake Downstream areas that will allow for Dirt and Sand to contact and adhere to the oil brought in as hot vapors guided by that short elbow "PCV" hose after condensing in the cool air-stream along the Interior Plenum in the cool air-stream inside are as follows:

(1) The Complete Absence of an Air Filter
(2) Loose or compromised Air Tubing and/or Loose or Mis-Aligned Hosing Clamps
(3) A Leaking or Completely Missing "Air Filter Cleanliness Warning Cannister" (Fall Off?)
(4) A Poorly Installed or Cracked Throttle Body Resonator (Box) & Disconnected Vacuum Hose !!!
(5) A Cracked Intake Manifold
(6) A Warped Intake Manifold
(7) A Loose Intake Manifold
(8) A Loose or Damaged Engine to Intake Manifold "PCV" Rubber Hose (Elbow)

 

[Mooseman]

Whoa everybody. Time out!

Before we condemn the motor or start ripping heads off, let's look at the symptoms. You say you found frothy oil in the air resonator plenum. It is NORMAL for the engine to blow back some oil mist into this area, which is the reason why the throttle body gets dirty. Now this time of the year, it gets cool out so it is entirely possible that the oil that accumulates in the resonator gets mixed with condensation. Now unless you find water in the oil (via a check on the dipstick), I would just clean out the resonator, change the oil (and get a sample to get it analyzed) and monitor.

Is the coolant level stable? Has it been getting lower without any obvious leaks?

For the P0014, pull out the CPAS and clean or replace it. Screens are probably clogged or the CPAS is failing. Might as well change it since it's not that expensive.

 

[stvrob]

I had only a few minutes to work on the truck today. I pulled the short double 90 hose from the intake plenum and there is no vacuum at all (from the valve cover) when the engine is running. Should I assume the orifice and/or the tube to the intake manifold is clogged? (I couldn't get that L shaped hose off with my fingers and ran out of daylight before I could find a way to get it off).

You asked if the coolant level was stable. About 2 weeks and 1,200 miles ago I had to add about 1/2 gallon of dexcool to the reservoir, Ive never had to do that before. (My wife may not have noticed it for some time prior...the level in the radiator was full though). Since that time it has remained at about the same level.

The small bit of froth inside the intake plenum, and a little bit just inside the filler cap area is the only evidence I have seen of water in the oil. On the other hand, its not particularly cold here (Northeast Florida), and the vehicle is generally driven by my wife who works 25 miles away, so it should be warming up well and driving this little bit of moisture out of the oil?

 

[stvrob]

Also, if it turns out that I am faced with the possibility of a head gasket leak, does anyone here have any experience with the "Steel Seal" solution?

https://www.steelseal.com/

 

[mrrsm]

Please read the latest edit further back in the discussion... as it modifies my impression about everything that is probably happening. Also, as ever... @Mooseman is the "Calm Voice of Reason" in his admonitions for you to do the checks he is recommending. The very last thing you want to have to do with this particular engine... is have to pull the engine head. So by all means... DO NOT ATTEMPT ANYTHING JUST YET.

There is a huge difference between pulling the Engine Head VALVE COVER to replace the gaskets... and performing an R&R of the ENGINE HEAD on the GM 4.2L Engine. The difference in difficulty here... is like comparing Applying a Band-AId to a Bee Sting... versus... Performing Human Brain Surgery on a Metastatic Gleoma Tumor!

As for the possibility of seeing Frothy Oil... On the outside chance that there it TOO MUCH OIL in the Crankcase...under some conditions... if the oil level is raised enough to make contact with the throws of the Crankshaft ... it will get whipped up into a seriously Frothy Brown Mess.. . exactly like an Electric Blender or Egg Beater can turn a Bowl of Egg Whites...into Frothy White Meringue.

Don't ask me how I know that culinary phenomena but its the best comparative example I can make.

 

[stvrob]

EDIT:

On a second read of the above Resonator to Short Hose information... I just realized that we are talking about Two Different Hoses: (1) The one mentioned above ventilates the space between the inside of the Valve Cover and the top of the engine head & valve train.... and (2) The one that I am referring to that is Dead Center at the bottom of the Intake Manifold (NOT THE RESONATOR) and IT evacuates atmosphere under pressure via that short elbow hose connected from the lower crankcase... consequently any blow-by gases can be vacuumed inside the Intake Manifold close to the area where the Intake Ports are located inside the head and thereby, the vapors get ingested and burned instead of escaping as noxious pollution.

Perhaps it contains enough crankcase oil in THAT vapor to settle on the inside the Intake Manifold adjacent the lower flange attachment points and THAT is where the oil is coming from... So instead of ONE PCV Valve and Routing Hose like in most other vehicles coming out of a valve cover and being routed back into the Intake Manifold... the Atlas Motor has TWO of them...ergo... Oil invading both the Resonator AND the Intake Manifold... But coming in from two different sources and locations!

If the Second Hose I just mentioned above is damaged , the top four frames from my Photobucket show the OEM Hose with the AC-Delco Part Number(s):

http://s557.photobucket.com/user/60...NEREPAIR/TRAILBLAZERENGINEPARTS?sort=3&page=5

EDIT:

On a second read of the above Resonator to Short Hose information... I just realized that we are talking about Two Different Hoses: (1) The one mentioned above ventilates the space between the inside of the Valve Cover and the top of the engine head & valve train.... and (2) The one that I am referring to that is Dead Center at the bottom of the Intake Manifold (NOT THE RESONATOR) and IT evacuates atmosphere under pressure via that short elbow hose connected from the lower crankcase... consequently any blow-by gases can be vacuumed inside the Intake Manifold close to the area where the Intake Ports are located inside the head and thereby, the vapors get ingested and burned instead of escaping as noxious pollution.

Perhaps it contains enough crankcase oil in THAT vapor to settle on the inside the Intake Manifold adjacent the lower flange attachment points and THAT is where the oil is coming from... So instead of ONE PCV Valve and Routing Hose like in most other vehicles coming out of a valve cover and being routed back into the Intake Manifold... the Atlas Motor has TWO of them...ergo... Oil invading both the Resonator AND the Intake Manifold... But coming in from two different sources and locations!

If the Second Hose I just mentioned above is damaged , the top four frames from my Photobucket show the OEM Hose with the AC-Delco Part Number(s):

http://s557.photobucket.com/user/60...NEREPAIR/TRAILBLAZERENGINEPARTS?sort=3&page=5

Just to be clear. Regarding the short double 90 degree hose connecting the bottom of the intake resonator to the top of the valve cover......Is this statement true.... that the only direction in which air should move thru this hose is from the resonator (clean air) TO the inside of the valve cover?

 

[AtlWrk]

In theory, yes.

But as I and Mooseman have stated, it is normal for small amounts of oil to work it's way into the intake resonator through this tube. I don't have a good explanation of how it does, but it does. And that, in and of itself, does not indicate any sort of issue with your engine

The only thing I can think is that while the direction is from the resonator to the valve cover, the actual volume of air is so low that there's not a whole lot of flow (velocity) to actually pull the oil back with it. If you look at the picture attached I highlighted the orifice that the PCV air is forced through before exiting the head. It's tiny, especially compared to that PCV hose.

 

[stvrob]

In theory, yes.

But as I and Mooseman have stated, it is normal for small amounts of oil to work it's way into the intake resonator through this tube. I don't have a good explanation of how it does, but it does. And that, in and of itself, does not indicate any sort of issue with your engine

The only thing I can think is that while the direction is from the resonator to the valve cover, the actual volume of air is so low that there's not a whole lot of flow (velocity) to actually pull the oil back with it. If you look at the picture attached I highlighted the orifice that the PCV air is forced through before exiting the head. It's tiny, especially compared to that PCV hose. View attachment 73926

Thanks.
When I pull that hose off the resonator, I can't feel any vacuum at all on the top of the valve cover. (at idle, I assume that should be maximum vacuum?)

Presently I am trying to remove that "L" hose from the other side to inspect that orifice. I'm not at all comfortable with the amount of force required to remove this hose, considering the manifold is plastic. Anyone have any hints for how to remove that hose?

I might (if I can gain access to it) try to fill that length of L hose with a few tablespoons of sea foam and let it work its way backwards thru the orifice if it seems clogged. Anyone think this is a bad idea?

 

[Sparky]

Vacuum would be on the other end, sucking out of the valve cover. You won't have vacuum pulling into the cover.

 

[stvrob]

Vacuum would be on the other end, sucking out of the valve cover. You won't have vacuum pulling into the cover.

I don't have vacuum sucking in either direction.

On the intake manifold side, I've pulled the L shaped hose off the manifold and found that I cannot blow down thru the orifice into the cyl head. Not sure how I am going to unclug it yet, maybe a few tablespoons of fuel injector cleaner? And let it dissolve its way downward thru the obstruction?

 

[stvrob]

Vacuum would be on the other end, sucking out of the valve cover. You won't have vacuum pulling into the cover.

This seems to be opposite direction from of what others have indicated.

 

[mrrsm]

The First Rule of the Hippocratic Oath for All Doctors is this:

"First... Do No Harm..."

As in Medicine... The same admonition can be said for making any Automotive Repairs. If you have no other dramatic problems such as Motor Oil floating on top of your Coolant Fluid in the Radiator... Or Coolant mixing with the Motor Oil in the Crankcase... and the Engine Performance is otherwise nominal with No Check Engine Light or DTC... Perhaps it is time to just button up the Resonator...check that all of the hose and clamps are snug... and enjoy the ride.

 

[AtlWrk]

There should be vacuum pulling into the valve cover. The hose connecting it to the resonator is upstream of the throttle body (near atmosphere/ambient pressure) providing clean, filtered air to the crankcase.

The "L" shaped hose connecting from the head to the intake manifold on the driver's side is downstream of the throttle plate and sees full engine vacuum. This is what pulls the dirty air from the crankcase (which coats the inside of the intake manifold and backside of the throttle body, the whole reason you were in there in the first place.

Anything you pour into that L tube will end up in your oil. I would go with sea foam knowing that you'll have to change your oil within a few hundred miles.

 

[stvrob]

The First Rule of the Hippocratic Oath for All Doctors is this:

"First... Do No Harm..."

As in Medicine... The same admonition can be said for making any Automotive Repairs. If you have no other dramatic problems such as Motor Oil floating on top of your Coolant Fluid in the Radiator... Or Coolant mixing with the Motor Oil in the Crankcase... and the Engine Performance is otherwise nominal with No Check Engine Light or DTC... Perhaps it is time to just button up the Resonator...check that all of the hose and clamps are snug... and enjoy the ride.

I get P0014 engine code. Other than that and the surging idle during cold start, it runs pretty good. My wife gets 20 mpg back and forth to work.

 

[stvrob]

There should be vacuum pulling into the valve cover. The hose connecting it to the resonator is upstream of the throttle body (near atmosphere/ambient pressure) providing clean, filtered air to the crankcase.

The "L" shaped hose connecting from the head to the intake manifold on the driver's side is downstream of the throttle plate and sees full engine vacuum. This is what pulls the dirty air from the crankcase (which coats the inside of the intake manifold and backside of the throttle body, the whole reason you were in there in the first place.

Anything you pour into that L tube will end up in your oil. I would go with sea foam knowing that you'll have to change your oil within a few hundred miles.

Thanks.
Right now, I cannot get anything to flow backwards thru the orifice. it seems pretty tightly clogged. Im thinking of using pressure but I dont want to damage anything. you think 30 or 40 PSI pushing backwards thru the orifice would be dangerous?

 

[mrrsm]

I get P0014 engine code. Other than that and the surging idle during cold start, it runs pretty good. My wife gets 20 mpg back and forth to work.

As previously recommended by @Mooseman ...

There are two sensors/solenoids than can either individually or in concert... actually cause the GM Atlas 4.2l Engine to stumble like an electrical misfiring problem, but not necessarily throw any codes while doing it because it has to do with very fine changes in variable oil pressure. Both are fairly inexpensive components to replace, but while one is fairly easy to R&R... the other is a PITA because you have to remove the three bolts holding the Power Steering Pump to the front of the engine in order to gain enough access to slide it out. Lets start with the easy one first:

CPS = Camshaft Position Solenoid (EASY)

This is a solenoid that picks up the physical position of the Exhaust Camshaft in relation to the position of the Reluctor inside the V-V-T (Variable Valve Timing) Sprocket and signals the PCM to make timing adjustments depending upon how far advanced or retarded the camshaft is changed depending upon the actions of the second solenoid actuator:

CPAS = Camshaft Position Actuator Solenoid (PITA)
(The Video OP Calls this a "Variable Valve Timing Sensor)

This unit is an oil pressure sensitive device that changes the internal positions of a helical gear inside the V-V-T based upon oil pressure either increasing or decreasing pressure depending upon Engine RPM. If the device internals and filter screen(s) are particularly dirty and or have metal particles in the oil stream blocking the entrance and exit of the oil under pressure, then the V-V-T helical gear will not perform correctly and the PCM can become misinformed causing a timing mistake when firing possibly throwing P0013 and or P0014 codes and making the engine stumble. It is possible to clean this device as shown in one of the below listed videos. However...considering how sensitive it is to very slight changes in oil pressure, it is recommended to be replaced with an OEM unit along with an oil change and oil filter replacement. This is yet another problem that can be reduced by doing more frequent oil changes using Mobil1 5W-30 Fully Synthetic Motor Oil and Filters or K&N Oil Filters to clean the oil of micro-fine offending metal particles in the oil stream.

This Video covers the Unboxing of the Delphi OEM CPAS unit:

This Video shows the R&R of the Old CPAS for the New CPAS:

 

[stvrob]

OK, Finally cleared the PCV orifice, it took about 15 psi air pressure, and I chased through a couple tablespoons of seafoam too. Also, a little bit of throttle body cleaner remained from an earlier attempt, so I guess I need to change the oil quite soon.

I am curious, if you change the oil before the oil change light comes on, do you use the same procedure to reset it? This truck doesnt have the percentage life remaining display, just the light that comes on.

 

[AtlWrk]

That's great news about clearing the PCV system This is the first time I've seen a confirmed case that it was clogged. Could be an easy and worthwhile "preventative maintenance" check for all of us.

The oil life monitor can be reset at any time whether or not the light has come on. The question now is: was your oil getting fouled up because of the inoperative PCV system (very likely, it's why it's there afterall) or did your PCV orifice get clogged because of fouled oil (from some other problem)? Hopefully it's the former and an oil change is all you need now. If that orifice was clogged I am worried what it might have also done to your CPAS or worse, the cam phaser itself to make it throw the P0014.

 

[stvrob]

That's great news about clearing the PCV system This is the first time I've seen a confirmed case that it was clogged. Could be an easy and worthwhile "preventative maintenance" check for all of us.

The oil life monitor can be reset at any time whether or not the light has come on. The question now is: was your oil getting fouled up because of the inoperative PCV system (very likely, it's why it's there afterall) or did your PCV orifice get clogged because of fouled oil (from some other problem)? Hopefully it's the former and an oil change is all you need now. If that orifice was clogged I am worried what it might have also done to your CPAS or worse, the cam phaser itself to make it throw the P0014.

I might still need to replace the CPAS. Also, I am going to start confirming proper crankcase circulation on a regular basis. I am thinking of adding a T with two valves between the orifice and the intake manifold so this can be checked regularly.
I think the clogged orifice led to several oil leaks, I'm hoping they will resolve themselves, but I have a lot to keep track of on this vehicle.

One observation, the dipstick seems to be hypersensitive to the vehicle being level. I checked the level during our Christmas travels and found that the level was below the dipstick entirely! It took two quarts to even touch the dipstick in my brothers driveway, but when I checked it down the road, it was overfilled. I may need to install a bubble level somewhere in the engine bay!

I am hoping that the PCV system had only been clogged since Christmas, and was simply due to this oil overfill, but I'm really not sure.

 

[Mooseman]

The plastic dipstick is a PITA to read. I switched it to the metal end one I grabbed from a junker. Much easier.

 

[59840Surfer]

@ Mooseman

You and I know that there's so much bad information in these posts - and even though they may be zombified, they are still searchable and can be found by people asking the same questions.

Sadly, they'll also be getting the wrong information every time.

I have a video that explains it a little better, but one of the worst ideas is that any oil or discharge from that valve cover nipple is normal. It is not.

The only thing the nipple does is restrict the air being drawn from the clean air side of the sound deadener chamber to sweep the crankcase clean of blowby and vapors of combustion.

There is no reverse flow of fumes and blowby - there should never be any emulsified oil/condensate (baby poop) inside the air chamber, going through the throttle body or filling the air chamber and leaking out of the "s-shaped" hose on the underside of the chamber.

Oil filling the spark plug pockets is another symptom of a failed crankcase ventilation system .. hereby called: The PCV System.

YES --- our 4.2s have a true-working PCV System - but don't go looking for it 'cause it's not what you think it should be. This ain't your grandfather's Oldsmobile!

Since our 4.2L engines don't have a MAF, but instead use a MAP - this happens to be a good way to make sure that there's at least a minimal amount of vacuum in the plenum behind the throttle plate at all time. It does this by limiting the throttle body response to keep the vacuum behind the butterfly from dropping to zero - or worse yet: positive pressure.

This is why you cannot go WOT at idle and won't get the throttle plate to respond in the same. This failure to WOT is an engineering design to keep the crankcase swept of blowby and other noxious vapors and redirect them into the combustion chamber, to be burned again.

PCV Systems are THE LAW and every vehicle will have one according to the DOT and The Federal Clean Air Act. So there!

IF the crankcase is not swept clean of combustion gasses and blowby, a byproduct of blowing up gasoline in a controlled space - the combustion chamber - creates water as a byproduct. This water (condensate) must be removed or it can create havoc in the engine:

1. VVT will stick in one position because of rust.​

2. Camshaft wear is increased because water is not a sufficient lubricant for such a very small point of extremely narrow contact between the cam and followers.​

3. Because oil is lighter than water - and floats - water is the first thing the oil pump sucks up at startup because the pickup screen is at the bottom of the pan - where the water likes to live when it condenses from vapors - when the engine cools off.​

4. Bearing surfaces cannot be lubricated by water either - not for long, anyway!​

So --- on to the PCV Mystery Video .....

Part 1:

Part 2:

 

[Mooseman]

Interesting however, riddle me this Batman,

- Why have the engineers programmed the PCM with built-in time based adjustments for the throttle body getting dirty? They knew that there would be some blow by coming back up that hose to the resonator and into the throttle body. The flaw with this system is when the battery is disconnected, it loses that adjustment and reverts to settings for a clean throttle body and causes idle issues.

- Although true that the PCM prevents the throttle from opening completely while in Park or Neutral, it will fully open to WOT while driving when commanded. At that point, there will be little to no vacuum and the blowby will overcome that low vacuum and some of it, along with some oil mist, will get into the resonator and throttle body.

There was a fair bit to read in this thread but apart from post #16 that incorrectly said that air should be coming out of that hose all the time (i.e. the resonator is the vacuum source), the rest is fairly accurate.

It's not a bad idea to clean that hose once in a while so it doesn't get plugged like the OP.

 

[59840Surfer]

Interesting however, riddle me this Batman,

- Why have the engineers programmed the PCM with built-in time based adjustments for the throttle body getting dirty? They knew that there would be some blow by coming back up that hose to the resonator and into the throttle body. The flaw with this system is when the battery is disconnected, it loses that adjustment and reverts to settings for a clean throttle body and causes idle issues.

- Although true that the PCM prevents the throttle from opening completely while in Park or Neutral, it will fully open to WOT while driving when commanded. At that point, there will be little to no vacuum and the blowby will overcome that low vacuum and some of it, along with some oil mist, will get into the resonator and throttle body.

There was a fair bit to read in this thread but apart from post #16 that incorrectly said that air should be coming out of that hose all the time (i.e. the resonator is the vacuum source), the rest is fairly accurate.

It's not a bad idea to clean that hose once in a while so it doesn't get plugged like the OP.

Well --- you got most of that wrong.

There was no real programming for oil getting into the throttle body since the ONLY thing the throttle body should EVER see was clean air from the air filter. Clean air -- only!

If service to this "non-existing" PCV system isn't performed on a regular basis - it will sludge up and then that crystalizes and forms a really hard crust that is pretty much non-destructible.

That nipple with the metered hole is always flowing inward - sucking air, if you will, from the air filter and into the valve cover and then it sweeps the crankcase and that contamination is then sucked into the intake runners to go through combustion and out the tailpipe. Easy-peasy.

The reason for the metered hole is to keep the crankcase from ever going neutral or positive and losing the PCV effect. If the intake is very small (eg: a restriction" or why, ask yourself, is it a very small hole? Huh? Riddle me THAT!) --- and vacuum/suction is supplied at the other end -- there is always going to be an atmospheric difference - ergo: a vacuum all the time.

√ That's the way it's SUPPOSED to be anyway.​

Federal Motor Vehicle Law and Air Quality Standards will not allow it to be otherwise. ALL vehicles will be equipped with a POSITIVE CRANKCASE VENTILLATION SYSTEM, CAPABLE OF REMOVING BLOWBY AND FUMES AND VAPORS. DOUBLESTOP.

Anything more (or less) is categorically wrong.

The MAP senses that there is either sufficient or insufficient vacuum in the plenum behind the butterfly and adjusts the throttle opening to compensate up to it's limitation or capability while still staying in-program.

Perhaps you interpreted that ↑ as an engineer with his crystal ball, deciding how this system would be ignored and ultimately fail. Not likely, nor is any assumption drawing to a false conclusion.

It will always report that value - vacuum or pressure.

Vacuum = GOOD​

Pressure = BAD.​

Binary -​

Boolean -​

Logical.​

The problem as I see it is that people don't realize the system is slowly plugging up until it's very late and it's when the baby poop starts flowing up under the oil cap, all over the dipstick and the VVT fails and then the constant advice to "clean the throttle body" starts coming around like flying monkeys as a cure.

Hell --- most owners and philosophers totally deny that a PCV system even exists on the 4.2L engine. Imagine that they think world is probably flat too.

Well --- that and "disconnect the battery to call the angels in for a miracle".

Disconnecting the battery is always bad advice for multi-many reasons of which I am not venturing on this date.

When the baby poop flows - it becomes a process of repairing the contamination and getting it to at least a modicum of operability to satisfy the computers.

As a "for instance" - my TB arrived with a large dose of baby poop and a Pampers-full sound chamber. It took me a few weeks to get the CV-side to operate at all ... and guess what?

No more baby poop.​

I also now have a lot snappier throttle response and acceleration and it is black-n-white.

When the system can operate at a reasonably close to designed-in values --- things run so much better --- but like gray hair and memory loss - it insidiously arrives on cat-like feet and it just screws things up -- slowly.

EDITED because my spell checker likes to make new words on me and delete consonants and change them to obscura.

 

[budwich]

does this apply to all 4.2 years? I don't have a hose on the intake on my 2008, it has a plug on the nipple.

 

[59840Surfer]

does this apply to all 4.2 years? I don't have a hose on the intake on my 2008, it has a plug on the nipple.

I'll have to check that out for you with a friend and his later model 4.2.

But can you get a few pixs or upload a short YT vid of your system and post the URL here?

 

[59840Surfer]

Interesting however, riddle me this Batman,

- Why have the engineers programmed the PCM with built-in time based adjustments for the throttle body getting dirty? They knew that there would be some blow by coming back up that hose to the resonator and into the throttle body. The flaw with this system is when the battery is disconnected, it loses that adjustment and reverts to settings for a clean throttle body and causes idle issues.

- Although true that the PCM prevents the throttle from opening completely while in Park or Neutral, it will fully open to WOT while driving when commanded. At that point, there will be little to no vacuum and the blowby will overcome that low vacuum and some of it, along with some oil mist, will get into the resonator and throttle body.

There was a fair bit to read in this thread but apart from post #16 that incorrectly said that air should be coming out of that hose all the time (i.e. the resonator is the vacuum source), the rest is fairly accurate.

It's not a bad idea to clean that hose once in a while so it doesn't get plugged like the OP.

Re-reading your reply got me to thinking a little bit about the efficiency of this whole PCV package ........

I'm going out on my favorite limb here and will concede one point .... the PCV is really designed to be operating at 100% ability to work correctly ... and I suggest that few --- if any of us --- owned our vehicles when they were new.

That leads me to conjecture-ise that when we took possession, they were already coking up with charred oily deposits and were in a death spiral around the drain.

So ... at best ... we've been dealing with a system that hasn't worked well for a long time and we don't have any idea how good it feels to have it running 4-0.

I can understand your rancor with me because it's hard to conceive what that might feel like ---running near-on perfectly.

I don't like arguing with moderators because they have a big hammer ...... ? !
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.

 

[budwich]

I'll have to check that out for you with a friend and his later model 4.2.

But can you get a few pixs or upload a short YT vid of your system and post the URL here?

I would if I could but I am not near my vehicle for a while. But I know that I have seen posts here in from people indicating the plug was missing on their vehicle (don't remember the years involved).... plus I pulled a plug from a 2008 in the scrap yard (as a spare because they have been known to deteriorate) so it not specific to my 2008. Perhaps I am thinking of a different point on the intake... sorry if that is the case. Watching the videos, they do appear to be the area that I am thinking about.

 

[59840Surfer]

Not having that particular plug on my TB --- I'd really really like to see a pix of it ... if possible, that is, and in whatever timeframe is possible.

TIA.

 

[TJBaker57]

We're not talking about this rectangular plug here, below the early model fuel pressure regulator vacuum port, right?

 

[59840Surfer]

No --- that's not it. Lessee if I have just a pix of it by its self .... BRB ...

Well --- I can't find a stationary pix, but I don't know if you saw the latest vid I made about the correct hose.

If not --- here it is --- and if so, then here it is again ...

 

[TJBaker57]

No --- that's not it. Lessee if I have just a pix of it by its self .... BRB ...

Well _I_ know that's not it! Just trying to perhaps clear that intake manifold port from the fold.

 

[59840Surfer]

TJ --- are you speaking to me in code? I don't see a 'fold'.