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Oil consumption, and possible PCV valve addition???

84K views 42 replies 23 participants last post by  Labrat0116 
#1 ·
If the reason for these 3.6L engines using so much oil is due to them not having a PCV valve installed, why couldn't we install an aftermarket PCV valve inline? Would doing so damage the engine, or has someone already done this and I'm a day late and a dollar short? If anyone has done this with success please let me know how you installed it, and what parts you used.
Thanks for the help.
 
#5 ·
I see the tubes that run from the valve covers to the TB, but there isn't any PCV valves to keep the oil from getting sucked through those tubes like a straw. I am just trying to come up with a way to keep my car from using so much oil. Some have suggested switching from synthetic to conventional oil. What are you thoughts on that? I have heard of some people having the rings, valve seals, and sometimes even the heads replaced due to the amount of oil consumption. I am just out from under the factory warranty though, and doubt that Cadillac would cover this unless there was any recall/service bulletin? What do y'all recommend, because I do not know what to do?
 
#6 ·
there is somebody on here who was having the same issues, and added either Lucas Oil, or the Purple whatever oil and it helped them out. i cant really relate, cause i drive the beast of the CTS, of course im referring about the 3.2L engine...i dont know if you searched on oil consumption in here, but you will see what i am talking about as far as what has helped some people...
 
#9 ·
Hi,

I'm on my first oil change for this 05 w/ a 3.6 engine. I've only owned it about 3 months. Personally I think it's the high rev's on the highway that's burning up this synthetic oil. I just put in a full quart after 3000 miles. But I think your on to something with the PCV not being in there.

TX Best 90 has anyone had any success w/ Amsoil using less oil consumption?

Keep a close eye on your oil and good luck with your ride.

Joe
 
#11 ·
Quote Originally Posted by Kingoftypos View Post
Still drugged up I see. Talking about the 3.2 being the beast. Ha Ha Ha

KOT
quote by tx
you know deep down inside the 3.2L engine was the best engine made for the CTS

3.2 may not have the most stock power but its not the least, and our only engine problem is our pcv system freezes causing the valve covers to leak..currently mine is but i have the gasket...its in the pile of parts for bout 7 months now lol....but they fixed that issue with a service bulletin...no oil consumption issues, no timing chain issues.
getting more and more glad the dealer turned down my offer on that 04 3.6..except i would have bought extended warranty and would still be covered.
 
#12 ·
I am thinking this is the problem for the oil consumption. I had a closer look, there definitely IS NO VALVE present - its a straight tube right from the top of the driver side valve cover right into what I will call the 2nd airbox (the plastic box between the air filter airbox and the throttle body). I REMOVED this 2nd airbox and there was about 3/4-1" of oil pooled on the bottom. The point at which the vent tube enters this 2nd airbox shows active and fresh oil stains as the oil must be consistently flowing through the ventilation system.

What possible reason could one have in designing an engine with NO PCV valve to retard large oil droplets from flowing through the tube right in the plastic air box between the air filter and throttle body? Makes you think, right?

I mean, a running engine is firing oil droplets randomly in every direction (primarily in the camshaft area in this case) - the purpose of this pvc valve is to prevent these droplets from entering the vent tube so they can fall back to the bottom of the cylinder head and get reclaimed by the lube system.

The major symptom of a stuck open PCV valve is over consumption of oil... who would stand to gain from all the CTS's out there consuming more than your average amount of oil? Who could it be? Maybe it's the people that have their name printed on your oil cap... Mobile 1? Is it possible that they have had some input on the PCV system (or lack thereof) and it's design? I AM NO CONSPIRACY THEORIST, but I demand to see reasoning behind this pcv design....

I would LOVE to hear a SOLID design summary and see some concrete engieering principles upon which the deisgn for the pcv was conceived. In my estimation - PISS POOR design.

I mean 1 qt every 1000 miles is disgusting - the EPA would go ballistic if they realized how extensive the issue is....

I plan to begin looking at some sort of pcv valve to prevent the oil loss issue. If anyone can tell me why some sort of valve to arrest the flow of oil droplets from the head cover right back in the intake was NOT needed - I would LOVE to hear it as it is entirely unapparent to me.

S in the D
 
#13 ·
Isn't the pcv valve located under the valve cover (driver side) ?

My car was using 1 qt per 12000 kms when I bought it. After reaching 120 000 kms up to 208 000 kms, it used 1 qt per 3500-4000 kms. I changed the 3 timing chains and tensioners and I'm back to 1 qt per 12 000 kms with 245 000 kms on the car.

Also, I don't think the problem is the pcv valve. GM is changing a lot of piston rings due to bad design and valve seal for the same reason.
 
#14 ·
Hello Men, Happy Holidays

I just had my second oil change on my 05 3.6 w/ 7000 miles on it. I used 2 quarts of Mobile 1 in between changes. Its a pain in the ass keeping up with this consumption. I have 58k on this car and I feel this is totally unacceptable with todays technology. I'm 62 (yes I'm old) and until I bought this CTS I haven't really kept up with all the changes since the 80's. I do remember when working on my 327 and 396 chevys years ago that the PCV valve was pretty important. If my memory serves me it was in between the right valve cover and the the air cleaner. We used to test them by pulling them off the hose and giving them a shake to see if the check rattled. If they gummed up we rinsed them in gas and we were good to go. I also recall them operating by changes in vacuum pressure opening and closing during acceleration and deceleration. I also remember seeing oil in the bottom of the air filter, but that was normal. Chevys used to use an O'ring that sat in a groove near the top of the valve. Some cars like Ford and Chrysler used what we called an umbrella or cup. Both designs basically deflected the oil away from the guide so it wouldn't end up in the cylinder. If you could afford to do it, the preferred method was to have the valve guides cut to accept a nylon type seal that worked very well. What I'm getting at is this. Today we have better seals (I hope) BUT we have 4 valves instead of two ( double the trouble) and the high revs are making these valves and guides work harder. I want to believe that the GM engineers have studied this thoroughly and would have fixed this problem by now. For now I will keep putting oil in and maybe I will go to a good old push rod engine again someday. Are CTS V's push rod??

Just my two cents from an old fart
 
#15 ·
Hey,

I have the same engine and the oild consumption is starting to happen more often then 1qt per 1000 miles. I did some searching and found a TSB that may help answer the question. A tech stated that replacing piston rings and valve guide seals may fix the issue. Is there a Install DIY/MOD for the PCV in the engine to help?

TSB Bulletin No.: 01-06-01-011E
 
#17 ·
Having done a rebuild on my 05 3.6L the guy who rebuilt the heads said the guides were prematurely worn (90,000 miles). Unfortunately I wasn't able to address the rings aside for a 24 hour soak in GM upper engine cleaner (incredible stuff by the way). I've also been told and can verify the front engine cover is also a prime candidate for oil loss.
 
#16 · (Edited)
The PCV valve isn't designed to prevent oil flow. It's designed to increase crankcase ventilation which is why PCV stands for Positive Crankcase Ventilation. Things like baffles in a valve cover and oil separators are designed to reduce the ingestion of oil itself. The ball or Check-valve in the PCV valve that we're all used to seeing is there in the event of a back-fire as well as to restrict/meter flow of this ventilation system. If the ENGINE didn't have a PCV system then these fumes that build up during the combustion process would never be forcefully pulled out and would break down engine oil quicker as well as increase the chances of oil caking up.

In the event of a back-fire, the check valve is shut to prevent the flame from leaving the intake manifold and entering the crank-case which has fumes from the oil heating up and slight blow-by (in a good running engine) which could ignite if this flame made it in. This valve also helps prevent boost from entering the engine in cases where the vehicle has forced induction.

There are other ways of creating a positive crank case ventilation system without having a check-valve designed system. On Jeep 4.0L's for instance that have the large and open fresh air inlet "Orfice" which allows air from the air filter box to enter the valve cover. A second "Orfice" allows the engine vacuum to pull the fumes out. Unlike the first orfice though, the second one on the vacuum side has a much smaller opening which prevents excessive flow. Couple this with baffles in the top of the valve cover and you now reduce the amount of oil that gets sucked up while still accomplishing the PCV process.

My friend's got an 05 CTS which has the timing chain noise and goes through over 2 quarts of oil between 3K oil changes using synthetic. I plan on doing the timing chain job this winter as well as replacing the plugs and bringing the rest of the car up to maintenance standards for the mileage. I hope to be able to find out more about the oil consumption and timing chain issues then but I'm willing to bet that if there is no serviceable PCV valve then the straw-like hoses mentioned already are designed in a similar fashion to the jeep orfice design.

Doug
 
#18 ·
Doug thank you for that awesome info.

briggy, quick question, are the valve guides aluminium on these engines?? If they are that would explain why they're wearing down so fast and allowing oil to pass. The valves need SOME oil but this is way too excessive. Do you recall what the valve seals look like also? I hope the're not still using those O'rings

Love this forum,

Joe
 
#19 ·
sorry don't have that info, just dropped em off at the machine shop. I do know they guy had a hard time finding the guides. I guess the dealer standard response is replace the heads. He ended up having to take dimensions on the guides and do a comparison check. How much oil is in fact coming through the guides/seals I don't know. I just say don't rule out stuff like the front cover.
 
#20 ·
I just started the timing chain job on my friend's 05 and wanted to follow up with some more info regarding the PCV system.



The first picture above shows where the fresh air for the PCV system comes from. There's a fitting on the air boot after the MAF that allows filtered air to enter the driver's side valve cover.



This second picture shows the other end of that hose connecting to the valve cover, it's just rearward of the last coil on that bank. If you note the convoluted tubing with the white label, that's the hose and it goes to a 45 degree fitting coming out of the valve cover that is under the brake booster vacuum hose shown in this picture above.



If you'll look at the intake plenum, there's a black hose that enters both sides of if, just below the shiny freeze plug looking component.




Spray the fitting down with some sort of lubrication and take a flat blade screw driver and twist it out. Be careful and use plenty of lube because the o-rings on this orfice tube can tear on the not-so-smooth aluminum plenum. As you can see in this picture, there's a little bit of orange still in the opening. That's where the o-ring tore a little bit.




On it's way out you'll notice that there's some resistance because of the length that it extends inward as well as the rear sections of the hoses being bolted down. See below pic for the rear section being unbolted from the backside of the intake plenum, just rearward of the brake booster hose which has the blue paint on it:






With the orfice removed completely from the intake you can look down in there with a flashlight and see that there's really not a lot of restriction in there (hopefully)




Above you'll see the where this other end of this vacuum related PCV hose seats on to a fitting from the passenger's side valve cover, just above the yellow fuel line label.




This picture shows the complete VACUUM side of the PCV system, upper left where it goes in to the passenger side valve cover and the there's a "T" on the backside of the intake and the hoses continue up to the middle/side of each bank.

The part that attaches to the passenger side valve cover has a spring loaded clip (it's just plastic that is bent to provide the spring action) that has to be carefully released to prevent it from braking, see pic below:



They split the vacuum hose portion so that, in theory, one bank alone is not saturated with all of the crank-case fumes/vapor/oil. Also, there is no function PCV valve like we're used to seeing, no check valve, spring and ball or whatever. It appears to be a restrictive hose where the diameter itself meters the airflow. With the vacuum side PCV hose off you can suck or blow in to any end of it the flow is the same and does not become blocked like a check valve would.

The underside of the intake plenum shows that oil is definitely making it's way in to the intake stream causing the oil consumption that we've been chasing since he bought the car used a year or so ago. The mileage on this model is just over 75,000.





Additionally, below you'll see two pictures of the spark plug. The first picture shows the white crusty build up that you could expect to see in an engine that has excessive oil making it's way to the combustion chamber.





This second picture shows the same plug rotated 180 degrees. Based on the lack of deposits on this side it would be easy to believe that the first side is the side facing the intake port itself where the oil would contact first and the second is cleaner because of the lack of exposure.










The last two pictures show the intake manifold itself, still attached to the engine. It's pretty clear that one bank has been exposed to more oil than the other but I really don't have an explanation as to why nor do I have a decent plan for reducing the problem. You can also note where the two hoses come together as one and then lead over to the valve cover. Also, it's important to note that if you plan on doing something with the PCV system you'll need to remember that you're dealing with a Mass Airflow Engine Management system. This means that any attempt to vent the PCV system, add in a catch can with a filter or stick one of those cool little air filters that fit on your pinky on the valve cover then you may create a fuel trim issue leading to a Rich/Lean condition. In other words, if you add in a catch can, it has to be sealed and only pulling air from the properly sealed up valve cover and getting it's fresh air from the post-maf filtered air.

Additionally, the PCV hoses shown above can become brittle on high mileage cars. The convoluted sections will become brittle and won't like to bend out of the way. Additionally, the softer rubber boot that goes to the driver's side valve cover will become softer and may not be a tight seal on high mileage cars as well. This again can cause a MAF trim issue and the solution will be to either replace the hose with a new one or put a hose clamp on it. From my experience, the hose clamp can work good for a while but if the boot is ultra soggy to begin with, the clamp will cut the hose and cause it to fail as well. Finally, if you don't use an OEM replacement hose and try to piece it together with hose from the parts store then you should know that not all hoses are equal. I've work on quite a number of cars where people put heater hose on where PCV hose was used before. This looks and fits fine for a while but give it a year or so and the hose that works for coolant will swell up the longer it's exposed to oil and crankcase vapors.
Doug
 
#21 ·


Some additional pictures now that the valve cover is off you can see the orfice in the back of the passenger side valve cover. It's just a small opening so the metering takes place here.



On the underside you can see that there are no baffles but the design of the cover will prevent oil from the lifters/cams/etc from sloshing directly up in to the orfice. Also, the openings on the underside of the orfice are quite small.



In addition to the separated passage you can see the back side of the cylinder head is cast in such a way that it will pull fumes from the head but it's certainly not a direct shot.
 
#26 ·
Bump!

I had my upper intake off of my 3.6L last night to replace my spark plugs, and I noticed the exact same issue. I have tons of residue in the intake runners (both banks). My intake elbow is also so wet with oil that when I tilt it from side to side you could watch the residue run and pool.

Any ideas?
 
#27 ·
Anybody posted what oil losses as like, a record quantity? I just got done driving 750 miles at fairly high average mph (70-80mph) on mostly flat kansas roads and my '05 3.6 sucked down 3 quarts of fresh mobil 1. I am not happy to discover that.
Okay so I've got an oil guzzler but you would think that oil consumption of this magnitude would produce a cloud of blue smoke out her back end...I never see anything and the back end of the car does not have any traces of oil droplets, fumes or smoke residues...so how does this work?
 
#28 ·
Kilowatt,
3qts in 750 miles? That is an absurd amount of oil loss. Are you sure, SURE, that it was full when you left? Do you have a leak anywhere? Even at WOT, that amount of oil being sucked down seems impossible... especially without any blue smoke.

The PCV system routes any and all oil pulled up directly into the air intake path, to be burned in the combustion chambers. The amount you described would have filled, plugged, closed off the air tube leading from your air filter to your throttle body. It is not possible for 3qts of oil to sit idly in your air tube or intake manifold... is it? I guess I could be full of sh!t on that one, as I have not checked how much oil can sit in the "second" air box, but it doesnt seem possible for your engine to consume 3qts (almost a gallon, over half of what the engine requires to be full) without blue smoke, or your engine dying from not oil, or your engine dying from too much oil and not enough fuel in the combustion chambers.

You said you were going 70-80mph, which is normally 2700rpms-ish. Oil does not burn as well as fuel. So when oil is present in the combustion chamber, the engine computer reads it as low-octane fuel, and pulls timing to compensate. This decreases power. Substantially, at that. Were your rpms above 2700 just cruising at 70mph? It seems your engine would have to be working extra hard to make that speed with reduced power.

Now, back to the ORIGINAL QUESTION... has anyone bought a simple PCV valve, and install it in place of the metering tube? Has anyone drilled out the metering tube to be nothing more than a straw leading to an actual PCV valve? I can understand that a lot of people are not willing to tackle custom mounting a PCV valve into the valve cover where the metering tube goes. But they do make inline PCV valves, I have seent them. Drill out the top and bottom of the metering tube to the fullest size possible, and install the PCV valve anywhere in the hose leading away from the metering tube. Nobody? Anybody?
 
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