: How to Clean The PCV tube on 05' CTS 3.6

02-23-12, 11:19 AM
Hey all, I bought a 2005 CTS a couple weeks ago. The previous owner told me ahead of time that the engine light might come on, he even gave me the print out of the code. It was the basic engine running lean CEL related to the PCV. I have looked everywhere on how to fix this without having to take it to the dealer as they want $400 to clean / replace it and from what I have read all it is on these cars is some tubing there is no actual PCV cylinder.

Autozone did not know much about it other than the fact that their computers told the guy there is no PCV on an 05' cts so it was not much help.

What exactly do I need to do? The tube is not in that bad of shape but he told me it was never replaced. Being over 50,000 miles I am guessing its probably gunked up and may be brittle as we get a full range of seasons here in Upstate NY.

Please let me know any info you have on this, as it seems like something that can be easily done on your own without paying an over priced mechanic. I love this car and want to get the idle issues straightened out!

02-23-12, 01:45 PM
I pulled the tube out today, honestly it was not in that bad of shape, I ran some pipe cleaners in it to see if anything would come out and it seemed rather clean except for a little bit of oil which is normal I am guessing.

Any help or information anyone has would be greatly appreciated.


02-23-12, 07:04 PM
Let me know if you want a solution to never have to have an upper induction cleaning again. Solves a ton of issues related to the oil ingestion.

02-24-12, 01:55 PM
I would love that.... Still have not found a solution for this problem.

02-24-12, 06:15 PM
Below is an explanation that is long, but detailed. I will also post pictures below to show the results. The solution is to trap, condense, and remove the oil vapors before they can ingest and cause all the gunk & carbon build up. The solution is ceap ($139) for the system needed for the 3.6.

Understanding the need for
a proper PCV oil separating catchcan

Any engine driven hard will ingest a certain amount of oil into the intake air system resulting in loss of power, detonation, and long term carbon buildup on the pistons & valves reducing the velocity and flow through the engine.

Preventing this on a street driven car subject to emissions requires some simple modifications to the closed OEM PCV system.

On all out race applications where emission rules do not apply, this is accomplished in different ways, but proper crankcase ventilation is a must! The crankcase gets filled with harmful combustion byproducts that if not evacuated will cause internal damage to your engine and shorten the usable life. These byproducts include: Sulfuric acids, abrasive carbon particles, unburnt fuel, water, and more. If you do not have a proper crankcase evacuation system these compounds will condense inside the engine and mix with the oil as well as begin corroding internal parts. It is NOT enough to just vent the crankcase pressure through a breather, but it must be flushed with a filtered fresh air source to carry these out & away. In an OEM system, these are burnt in the combustion chamber & further in the catalytic converters.

In an off-road or race application, the engine is normally not used to burn them off.
At the very least drag only motors have a scavenge evac system in the header collectors to pull vac, and anyone that's serious has a belt driven vac pump.....especially the Alky motors due to the amount of moisture the alcohol introduces to the crankcase.
Want to see whats in your oil? A simple oil analysis will show you how much harmful stuff ends up in it.

The oil analysis will show the acid build up....and no, it takes a year or two before you would see any substantial damage to your internal engine parts.....but an easy way is after 6 months or so of running like you describe pull a valve cover and look and the corrosion from the vapors on your rocker arms. This is the first place it is visible.

Bottom line is, w/out a proper evac system you WILL sustain long term engine damage. It may take a few years to notice, but I build motors 6 days a week when not racing and see the results first hand.

There are several other ways for oil mist to enter the intake manifold, the PCV system is the most common with the fresh air make up source (the fitting on the top rear of your throttle body) being the second most common. To eliminate that you need to cap the TB fitting and run a valve cover breather (installed as far from the crankcase vent as possible...ideally you want to pull filtered fresh air in one valve cover & evac it out the other or the LS6/LS2 style valley cover is second best) Then if it is excess crankcase pressure pushing oil vapor/mist out faster than the PCV can evac it you will see it pushed back through the line from the pass valve cover front to the TB and it is ingested from there. Want to see whats in your intake manifold? Simply remove the 4 10mm bolts that hold the TB to the intake manifold. Take a white paper towel and reach into the intake manifold snout, rub it around, and pull it out. V6 LLT owners...just inside the intake opening you will see a deep collection well that accumulates oil. The 3rd point of ingestion is from reversion. This of course needs at least one piston/ring/bore/valveguide or seal issue that is allowing oil to be pulled into that one or more intake port and at high RPM's the reversion pulse will "push" that oil throughout the entire intake manifold. It will appear to have entered from the vac fitting that the PCV system uses but is really from one of the cylinders (reversion is a whole different process that is not widely understood but do a Google search and you can actually find some super high speed video of engines on dyno's where at high RPM's...9-10-12K plus the reversion cloud of A/F mixture is actually rising out of the intake runners or carb on a non fuel injected motor). To test for that just place a clean clear fuel filter inline between the catch can outlet and the vac fitting. If it gets oil on the can side, oil is coming through the can. If it first appears on the intake vacuum side, then it is reversion so you have a deeper issue.

Here is direct from GM on a service procedure:

Throttle body service is the throttle body cleaning and wiping of the bore and throttle blade. The service is important in order to keep the automobile running smoothly, efficiently, and safely.
There is carbon and sludge that the PCV system deposits into the throttle body as the engine operates. This carbon and sludge is cleaned out during the throttle body service. How well the engine operates about a year after service is determined by the way the automobile starts, how well it idles when it’s cold or warm, and when accessories such air conditioning and heat are operating. The carbon and sludge will also affect the way the car starts from a total stop. A service such as this will keep the idle valve, which is computer controlled, clean. If it is left dirty and covered with carbon, it will have to be replaced and such a replacement can be costly.
An important part of the engine is the throttle body, which is part of the air intake system. The air intake system increases the amount of oxygen used for combustion with fuel. You can either gain or lose power with the air intake system depending on the vehicle’s ram. The throttle body is a part of this air intake system. Keeping the throttle body in good operating condition will keep the car running without costly occurrences.
Importance of the Throttle Body Service
Careful and regular throttle body service will keep the emissions from the engine’s exhaust system in check. There is also increased sound when the throttle is applied by way of the accelerator. If the vehicle is operated at lower speeds, there is less noise coming from the engine. However, at higher speeds, the engine tends to become very noisy. These two statements make the throttle body service important in itself, as it makes the automobile more environmentally friendly. A complete throttle body service is recommended every 15,000, 40,000, and 75,000 miles to be sure that the automobile is functioning properly.
It is most important to have the throttle body serviced regularly to avoid the high cost of replacement. The cost of throttle body service or replacing the throttle body varies with the year, make, and model of the car. But, no matter what that year, model, or make may be, replacement is not inexpensive. Excluding the cost of replacing the throttle body for the moment, what is perhaps even more important, is to have the throttle body serviced regularly to keep your car running smoothly and efficiently.

Having engine smoke or excess crankcase pressure? There may be a deeper issue. On the LS motors we pull apart it is usually # 7 ringland broken between the compression & middle ring, or the land itself broke off at the top. We also find the top ringland pinched or crushed down on the top ring (comp. ring) and metal transfer along the piston side has caused the oil & scraper ring to stick allowing oil & blow-by. Also, try this: at idle (vac is at it's greatest when at idle or when the throttle blade closes from high RPM's) remove the oil fill cap and hold your hand over it. Does it pull a slight suction? If so, all is good with most of the system and I doubt you have a damaged piston/ring/bore. But if there is ANY pressure pushing back you have a deeper issue and that is the cause of the oil problem.

Now on big cam/stroker builds a can inline on the dirty side, and a can inline from the fresh air source may be needed (the bigger the bore & longer the stroke, the more crankcase pressure is built up) If it is forced induction, then you have a whole new process to deal with......and that is the PCV system works properly when at idle & non-boost, but when you start making boost you have switched from the intake manifold being negative atmosphere to a pressurized component and the PCV system is rendered useless and pressure escapes wherever it can. The solution then is to have one way check valves inline so the vacuum need for proper evacuation comes from in front of the compressor (head unit) through a line run to the air filter.

This is getting a bit long and I hope all can follow this, but if not ask me specific questions for clarification so this helps all. I'll go over every type of solution and the pros & cons of each....and remember, this problem is NOT just in the GM LS based engines, but is an issue with ALL modern closed systems. We just tear into our cars where as the Mercedes or Lincoln owner never even realizes there is an issue.

I also wanted to address the water in the oil. You will NOT fill your crankcase up in short order with just breathers. What happens is each time your engine reaches operating temp the unburnt fuel, water vapor, combustion by-products will gas or "flash-off" as vapor. But only the excess crankcase pressure being relieved through the breather will carry any of that out....and without a proper evac system, a good amount remains in the crankcase and re-condenses back to droplets that coat the internal engine parts as your motor cools down and it contaminates the oil. Every time you heat cycle you are adding more contamination and it is not very visible to just "look" at your oil....you need a professional analysis to see just what is accumulating in your oil and how it is breaking down its ability to protect...but the corrosion from the sulfuric acid is also very damaging over time (I'll try to post up some pics of parts showing just this in the near future). Just pull the dipstick on a diesel 20 miles after an oil change...it already "looks" black & dirty, but is still new and providing the proper protection. Sight is deceiving. Oil might look pretty clean or dirty but an analysis report will show destructive levels of contaminants.

And finally, some have gone so far as to cap off the entire system and run an open hose from each valve cover to near the ground. While this will eliminate all oil getting into the intake via the PCV system, the damage done by the hose with the least amount of air moving past it while at speed will suck dirt/sand/dust/water/and who knows what else directly into the motor via that valve cover. It may take some time (depending on how clean the roads you drive on are) but will result in premature engine wear & failure.

The solution for the street crowd is a properly designed, good functioning oil separating catchcan. Many are available on the market, but ONLY ones designed with internal baffling and a good distance separating the inlet from the outlet. Many of the cans seen for low prices on Ebay, etc. are great looking, but are nothing but empty cans with two fittings attached. Do your homework & get a full understanding before you make your selection.

Here are pictures of the ingestion first hand:


and this is a 3.6 that had the oil separating PCV system on since new on the left, and as it comes from the factory right:

Below see how much caron ridge is already building up from the ingestion. As the hard abrasive particles break off they can become trapped between the piston & cylinder bore causing scoring and accelerated engine wear.:

Here is the piston top on a 3.6 DI. The quench area and burn pattern are negatively affected from the build up resulting in less power & fuel economy. The build up in the throttle body (not shown) causes a stumble and CEL light as the air cannot transiton evenly as the blade opens.


Keep in mind, both examples are a motor with 12 k miles on. The intake manifold pics are app 5k miles each and you can see the RX system stops ALL oil from entering (unless there is a piston/ring/cylinder seal issue) something no other catch can can claim.

The other path for oil ingestion, allthough not nearly as much enters, is the OEM fresh air tube. At WOT or "spirited" driving when there is little vacuum present in the intake manifold, oil is drawn back through into the air bridge upstream of the throttle body and is ingested this way.

The solution is to delete the OEM fresh air tube and install a breathered oilfill capto replace the filtered fresh air source. The problem with this is a plain open breather will allow excess unmetered air in that the ECU cannot adapt to and the fuel trims go crazy trying to adjust. The RX breather kits have integrated flow controlling check valves that only allow a controlled amount in so the ECU is able to adapt within the factory parameters.

Never needing an upper induction cleaning service (well say maybe 100k miles) or throttle body cleaning service.

The can has to emptied every oil change to drain the contaminated trapped oil and other compounds, but other than that it is trouble free the life of a vehicle.

Another benefit is 1-3 mpg improvement as the ECU is not pulling timing due to the detonation caused by the oil ingestion.

Have questions? Just ask......have 38 years of doing this and am always happy share the knowledge learned.

06-05-12, 05:32 PM
Hey SC2150, thanks for the explanation.
Can you give some more information on the solution? Is this a kit? Or is it a DIY?

07-19-12, 10:38 AM
I have a better and cheaper solution - use top tier gas, like Shell premium, and a good synthetic oil, like Pennzoil Platinum, and Techron or Berryman's in the tank from time to time. On the SAME engine as the OP (not the DI pics shown above), after 161K miles, this is what the valves looked like:

http://im1.shutterfly.com/media/47a1cf01b3127ccefefc00f6715400000030O08IZtXLZszag9 vPhI/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

http://im1.shutterfly.com/media/47a1cf01b3127ccefefd41d2118400000030O08IZtXLZszag9 vPhI/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

http://im1.shutterfly.com/media/47a1cf01b3127ccefefd7ffd11b400000030O08IZtXLZszag9 vPhI/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

And don't believe anyone that says you don't get the same effect on a GM DI motor. GM specifically designed this engine by uniquely positioning and timing the injector and valves in order to assist a top tier fuel in cleaning the intake valves.

If you have 15 seconds (00:25 to 00:40), you will see fuel being sprayed onto the intake valves during the intake stroke:

http://www.youtube.com/watch?v=qd90yHlmfS4 (http://www.youtube.com/watch?v=qd90yHlmfS4)

The valves are clearly sprayed with fuel while open on the intake cycle and before compression or ignition.

For more (and accurate) information, http://www.autoobserver.com/2011/06/direct-injection-fouls-some-early-adopters.html

07-20-12, 08:35 PM
It is available in a DYI kit and is easy to install.

Also, please do not get sidetracked by misinformation.

The animation is off a little. The fuel is sprayed directly into the combustion chamber and never toches the tulip side of the intake valves on any DI motor. In the animation it appears the fuel is sprayed into the combustion chamber when near the bottom of the intake stroke, but it is actually injected on the compression stroke and that is why there is little chance of pre-ignition from a glowing piece of carbon as is common with port injection.

We had a visit from a GM drivetrain specialist today that covers the entire State of FL and has been watching the forums. We spent app 2 hours showing him the results first hand and discussing this and other issues. We broke out the boroscope and showed him some very low mileage cars engines in here (below 10k miles) and it was very informational for both. We installed a RX oil separating catchcan system on the company full size truck he was driving and sent the latest LFX version with him. We are also shipping him one of are just released VMax CNC ported LFX throttle bodies for testing next week.

No, there will never be one of these installed from the factory as 99% of todays buyers have no clue this is an issue, and only the true super cars seem to be dealing with it properly.

So, anyone doubting ANYTHING here, please stop in and see in person. We have always multiple engines in different stages of teardown or build and you can see.....will even remove your IM and let you look in person with the boroscope to see. We are always open to visits, and the only way sometimes to sort through BS is to see it in person.

Also, all these photos and more can be viewed on Photobucket :http://photobucket.com/revx1

We have anything from ferraris to fords in here but are mainly a GM shop, and current builds you may want to see in person include a 32 ford for the Discovery Channels Deadliest Catch:

Below is a picture of a non DI 3.6 with just over 60k miles on it, and as you can see.....even with todays fuels the port injection motors will suffer from this issue, but not nearly as badley:

Notice this looks a little different:


And here are some I have posted before from a 8k miles DI 3.6:


Without the oil ingestion causing these long term issues, the short term benefits are pretty dramatic and near immeadiate as any oil ingestion into the intake aircharge will result in an incomplete burn and poor fuel economy and performance (all documented in the links below with all makes/models/engines domestic and foriegn) but the detonation that results will cause the ECU/PCM to pull timing resulting in even more performance and economy degradation.

Unless you engine is a 2 stroke designed to burn specially formulated clean 2 stroke oils, engine oil does no good entering the combustion chamber and a 1-3 mpg improvement is the average result after trapping this oil before ingestion.

Try yourself. Pour a small amount of your engine oil brand onto a plate and try and light it on fire......it wont burn, and in the combustion chamber this has a negative effect on the burn pattern and over time the deposits negatively effect the quench area as well. All this contributes to the gradual loss of performance and fuel economy. Add up what you spend in fuel and would 1-2-3 mpg save you some $ over time? And the deposits you see do break off at times and are as hard as any abrasive and the samller particles will get trapped between the pistons and cylinder walss causing scouring and contributing to oil consumption. Also, look at the ringlands from this.....the rings need to move freely to do there job and seal the crankcase from the combustion chamber:

effects on the intercooler for any CTSV owners:

A view into the average intake manifold showing the oil ingestion:

With a port injection motor the fuel is introduced into the intake runner and the fuel/air mixture will pass the intake valves allowing a top tier additive fuel to reduce the gunk/deposit buildup, but nothing but air passes the intake valves on a DI motor causing the rapid buildup of gunk as shown. The only way to prevent this is to stop the oil ingestion before it enters the intake manifold. Your dealer will reccomend an upper induction cleaning service evry 12-15k miles, but you can prevent it from the start by trapping the oil before it enters the intake air charge.

GM is not alone with this, and all DI motors suffer from this issue which gradually reduces power & efficiency over time.

Below are links on the subject with every domestic & foriegn DI motor today. On the BMW mini, we are having to remove the cylinder head at 40-60k miles and do a manual valve job to restore the flow to factory specs. Volumetric efficiency is so important on the DI motors to achieve the power and economy they produce over older port injection motors and it is critical to keep them clean.

Anyone doubting any of this can stop in in person and see as we constantly have these engines apart doing repairs/rebuilds/and performance mods.

This link will give you data from a technical standpoint to verify what i have shared above:

And as you can see GM is not alone with this issue:

Edmounds actually has a formula as to how much power/fuel degradation is realized from these deposits:


And more Q&A on the subject from inustry engineers:

Fords also have the issue:


And BMW, Mercedes, and Audi all battle it:



and more for any that doubt or follow misinformation posts:





I urge all to read these in detail and learn. Many contain detailed pictures of either the engines dissasembeld or via a boroscope, and they are from around the world by automotive techs and engineers in the industry....not a backyard guy that has made assumptions.

This can all be prevented and the performance and fuel economy of new retained, but that is for another thread for any that want details. This is just factual data on the subject....and again, Any and all are welcome to stop in in person M-Sat to see these motors in person if there is any doubt after taking the time to click on these links and read in detail.

07-24-12, 03:36 PM
Folks, the fact is, GM designed these motors so that any deposits are inconsequential, if their maintenance recommendations are followed. Most of the information that this aftermarket vendor is supplying has nothing to do with GM V6 engines. He calls me and GM engineers misinformed, but has yet to provide anything other than anecdotal information about the benefits of catch cans on stock engines. He has never produced an oil analysis on a catch can vehicle with a stock GM V6 like ours, and no one has taken apart an engine that was poorly maintained (but with a catch can) to see if a catch that makes a difference over the long haul. He just cannot prove what he is selling, so he takes to attacking anyone who calls for proof, and drowns threads with his link dumps. Spend some time researching, and you will see he has done it on all kinds of boards.

07-24-12, 06:59 PM
These outright lies have got to stop.......stick to a subject you know, and this certainly isnt it. I have asked you to stop your interference time and time again....yet you still ignore all the data, all the proof, all the automotive engineers technical papers on this. You can chose to mistreat your car as you want (166,000 miles without changing spark plugs, and then showing us pictures of no electrode left and you expect to have any credability?)

Engnineering Systems
07-24-12, 07:27 PM
I usually lurk in the background, but this is getting out of hand. SC2150 has the up-most knowledge on this matter and I have personally been to his shop and inspected engines both with and without catch cans. It is in fact a fact that without fuel spraying on the valve stems that they will in fact lose efficiency and need cleaning, this is published by GM.

Service Information
Home Publications Number Search New Bulletins Bulletin Search Feedback Help
2011 Cadillac CTS | CTS VIN D Service Manual | Document ID: 2863222
#PIP5029: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves - (May 29, 2012)
Subject: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves

Models: 2008 - 2012 Cadillac CTS, STS
2008 - 2010 Chevrolet Cobalt SS, HHR SS
2007 - 2010 Pontiac Solstice GXP
2007 - 2010 Saturn Sky Redline
2009 - 2012 Buick Enclave
2009 - 2012 Buick Lacrosse
2009 - 2012 Chevrolet Traverse
2009 - 2012 GMC Acadia
2009 Saturn Outlook
2010 - 2012 Cadillac SRX
2010 - 2012 Chevrolet Camaro, Equinox
2010 - 2012 GMC Terrain
With any of the Following Direct Injected Gasoline Engines:
2.0 (RPO LNF)
2.4L (RPO LAF, LEA, or LUK)
2.8L (RPO LAU)
3.0L (RPO LF1)
3.6L (RPO LFX or LLT)

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may complain of a MIL and engine misfire. In some cases, the misfire may be more apparent on a cold start, may count on a single cylinder or several cylinders, and may or may not be felt by the driver. Upon inspection, the technician will find one or more misfire codes (DTC P0300-P0306) stored in the ECM and SI diagnosis may or may not isolate the cause of the misfire depending on whether the intake/exhaust valves are sticking at the time of the diagnosis.

This may be the result of major carbon build up on the intake and/or exhaust valves as shown below so the misfires should not have appeared until the engine has accumulated around 5,000 miles or more.








If this concern is encountered, perform SI diagnosis. If SI diagnosis isolates a valve sealing concern and/or eliminates everything else external to the engine, decarbon the engine with Upper Engine and Fuel Injector Cleaner by following the guidelines below:

Important Extreme care must be taken not to hydrolock the engine when inducing the cleaner, especially if it is induced without Kent Moore Tool # J-35800-A. If too much cleaner is induced at too low of a RPM, or if you force the engine to stall by inducing too much cleaner at once, the engine may hydrolock and bend a connecting rod(s).
1. In a well-ventilated area with the engine at operating temperature, slowly/carefully induce a bottle of GM Upper Engine and Fuel Injection Cleaner into the engine with RPM off of idle enough to prevent it from stalling (typically around 2,000 RPM or so). Depending on the engine configuration, induce the cleaner through the throttle body or an engine vacuum hose/pipe. For best results, it is suggested to induce the cleaner with Kent Moore Tool # J-35800-A (shown below).
2. Turn the engine off after inducing the cleaner and allow the cleaner to soak with the engine off for 2.5 to 3 hours (Do not let cleaner soak for more than 3 hours as remaining deposits may start to harden back up again).
3. Add a bottle of GM Fuel System Treatment Plus to the fuel tank and fill the vehicle with one of the Top Tier gasolines listed at http://www.toptiergas.com and/or in the latest version of 04-06-04-047 (USA) or 05-06-04-022 (Canada). See Bulletin 05-00-89-078 for more details on GM Fuel System Treatment Plus.
4. Test drive the vehicle extensively to circulate the GM Fuel System Treatment Plus, which will help to eliminate/reduce any remaining intake valve deposits.
5. Re-evaluate the concern to determine if it is repaired or improved at all. If the concern is improved but not repaired, it may be necessary to perform the above decarboning process a 2nd time.

6. To complete the repairs, advise the customer to only use one of the Top Tier Gasolines listed at http://www.toptiergas.com and/or in the latest version of 04-06-04-047 (USA) or 05-06-04-022 (Canada) to minimize future deposits. It can also be recommended to add a bottle of GM Fuel System Treatment Plus at every oil change as mentioned in the latest version of 04-06-04-051.
Kent Moore Tool # J-35800-A
Upper Engine and Fuel Injector Cleaner

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

2012 General Motors. All rights reserved.

By utilizing the catch can you will reduce to eliminate most of the deposits that build up on the valve stems, I have had one on my engine now for quite a while and using a bore light I have seen very little to no build up, and especially I have not had to have this costly cleaning done. If I had not had this catch can I would have spent over twice the cost for upper induction cleanings. I am in the Industry and see the added benefit of using this system. SO before you try and dis-credit SC2150 you better have a lot more than your un-proven opinion and back up your shortcomings with real world facts.

07-24-12, 07:44 PM
I may have missed it somewhere but the cts does have a pcv valve. Kind of. The reason for the price from the dealer is because the valve cover needs to be removed to clean the backside of the nipple where the hise attaches. There are 2 small orifices that can plug due to lack of oil changes. Typically when it is plugged solid you will find oil in the intake duct between the throttle body and air filter housing

Engnineering Systems
07-24-12, 07:48 PM
Crankcase Ventilation System Description

A crankcase ventilation system is used to consume crankcase vapors created during the combustion process instead of venting them to the atmosphere.

Fresh air is supplied through a filter to the crankcase, the crankcase mixes the fresh air with the blow-by gases and then passed through a positive crankcase ventilation (PCV) orificed tube into the intake manifold.

The PCV orificed tube restricts the flow rate of the blow-by gases using an orifice (1) located at the end of the tube. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the throttle body in order to be consumed by normal combustion.
2012 General Motors. All rights reserved.

Still getting unused crap in the intake and causing the above problem, hence a catch can and a breather is great preventative maintenance.

07-24-12, 08:11 PM
Amen........thanks Enineering. And glover, the valve cover removal is a dealer service for cleaning, but either way all modern engines on the road today domestic and foriegn have this same issue, just some are more prone to it and there is no way to prevent the gunk buildup shown in the GM TSB's except by trapping it before ingestion. Yes, clogging of the fixed orfice tubes is an issue that can cause even more, but the solution right from the start is to trap it and prevent it from forming. The fuel savings alone pays for it in a short time depending on the miles driven as most see 1-3 mpg improvement when trapping the oil ingestion before it enters the intake air charge.


07-25-12, 08:21 AM
If I had not had this catch can I would have spent over twice the cost for upper induction cleanings. I am in the Industry and see the added benefit of using this system.

Well then, maybe you can use engineering analysis to see why things you are saying don't make sense. Clearly, not all GM DI engines require upper induction cleanings - will you grant even that? And doesn't the bulletin itself say that the repair is not complete until you advise the customer to use top tier gas, as I have been saying all along? And GM didn't recommend the installation of a catch can, did it?

What kind of gas are you using? How can you possibly say that it's the catch can, and not the fuel, that is keeping your intake valves clean?

It is a "real world fact" that my engine went 161K miles with clean valves and no catch can or upper induction cleaning. It is a real world fact that at least one other LY7 has done so. It is a real world fact that the only used oil analyses posted in these forums show that some catch can equipped cars have fuel dilution. It is a real world fact that no one has shown that light carbon deposits in an intake that are not on the valves makes any meaningful difference in a stock engine. It is a real world fact that GM has designed their DI engines to minimize fuel deposits on intake valves.

I am not trying to discredit anyone, I just think the assumption that the catch can is collecting, rather than creating, is an unproven one.

07-25-12, 08:48 AM
You wont quit will you.....all catchcans are not the same, and no catch can causes fuel dilution...it is impossible, RX or other.

I think his pictures show pretty much "real world" and the fact that this is what we do....build and rebuild engines, and every picture except yours shows the gunk build-up.

The gunk buiuldup is caused by the oil ingestion.....trap the oil before it is ingested and you have no buildup plain and simple.
And it has been pointed out over and over again "NO FUEL TOUCHES the intake side of the valves where the gunk deposits form.....so it does not matter what fuel is used on DI motors. The fuel is introduced directly into the combustion chamber on the only in the combustion chamber for a milisecond. For a top tier fuel, or fuel additive to have any effect on keep valves clean it has to be a port injected or carburated engine where the aitr/fuel mixture passes the intake side of the valves allowing it to contack the sureface where the deposits form.

07-25-12, 10:23 AM
OP asked for ideas how to clean his PCV. He didn't ask for romper room.

SC2150, and ktr-sb; if you two children cannot play nice, you will both be gone.