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AFM Question - 2011 Avalanche
- Thread starter EMSDC
- Start date
Of course it's fair......to assume new GM systems are properly thought out prior to production is naive. In addition to 4/6/8, there was the Olds diesel built on the gas small block, the early turbo Buick V6. the early 700R4 tranny...... I'm all for innovation and in all cases it wouldn't have been so bad if GM had made the victims whole. But they didn't. Customers were mostly left holding the bag and beating on the stone wall of denial and whut?
ltxi said:
They can and do make great products.....problems arise when they try to cater to a high tech upscale crowds like Olds (which was always the testing grounds before Caddy upgrades) or to meet last minute requirements for Government regulations.The Olds diesel was brought about due in part to the rising cost of gasoline compared to diesel and lack of Government emission requirements for diesel engines. So they took a perfectly good gas engine design and converted it to diesel and without taking the time or effort to design or tool up for strengthening the bottom end to handle the greater loads. The only solution was to retrofit it back as a gas engine which I understand GM did for low mileage vehicles even if out of warranty. If is wasn't for Government mileage requirements there never would have been an AFM.......a 7000 lb vehicle needs a powerful V8....so what's the next solution after dumping AFM?..... go to a V6 for next year's truck line that's kludged up with gimmicks similar to AFM to give better mileage and similar hp on paper, time will judge the merits of this change.
Personally, I hate V6s...had 'em in a Chevy Citation and minivans, a POS.......they are kludged design to fit a 6 cylinder motor transversely into the limited space under a front drive hood. An unbalanced design with bad harmonics that has to be doped up to run as smooth as an inherently balanced V4, V8, or V12. More engineering goes into the design of the motor mounts to shield the vibrational imbalances than into the design of the engine to remove the bad harmonics, e.g. counter rotating balance shafts. The whole concept of 2 cylinders opposing 1 on a power stroke in a 90 degree V8 configurations is not an advance to a truck, probably being done so they could interchange engines from their current smaller FWD/AWD vehicles. The future will show how well they work in truck applications. Large vehicles the size of an Avy/Silverado/Suburban have the space under the hood and would likely be better served with a large I6, mid size V8 or small block V12 configuration.
Given the speed of emerging technologies, ever onerous Government regulations and pressure to make yearly changes to keep market share and attract new buyers, customers will always be left holding the bag because the environment is not conducive to a zero defects design and production......and whether GM or any other automaker, the customer will ultimately always be the one holding the bag for unforseen adverse design changes.
So, when I finally turn off my AFM, I expect to hear the same odd exhaust note, while idling - since AFM shouldn't be active, then.
Nick
[/quote]
Now I just have to save a few bucks to get a new tuner to disable AFM.
[/quote]
Just turned AFM off yesterday on my '07 and I seriously feel like a huge weight has been lifted off my back...I've had my avy for about 3 months and noticed oil consumption within the first week, that's when I started researching and found "the club" and also about the design flaws of AFM. Every time I've driven my new truck since then I haven't truly enjoyed it due to the visions in my head of oil splashing and gunk building up in my cylinders. Since yesterday I'm feeling good about buying the truck that I always wanted back before I knew some of the dumb stuff that commonly goes wrong with them. The inTune is a handy little device and I anticipate I'll like it more as I figure out how to tweak it. And just a thought on the range device...$200 for just that seems pointless when a brand new intune can be had for $380 or less. Diablosport even has a $100 credit right now for turning in an old predator. Turn it off fellas, get your peace of mind.
Nick
[/quote]
Now I just have to save a few bucks to get a new tuner to disable AFM.
[/quote]
Just turned AFM off yesterday on my '07 and I seriously feel like a huge weight has been lifted off my back...I've had my avy for about 3 months and noticed oil consumption within the first week, that's when I started researching and found "the club" and also about the design flaws of AFM. Every time I've driven my new truck since then I haven't truly enjoyed it due to the visions in my head of oil splashing and gunk building up in my cylinders. Since yesterday I'm feeling good about buying the truck that I always wanted back before I knew some of the dumb stuff that commonly goes wrong with them. The inTune is a handy little device and I anticipate I'll like it more as I figure out how to tweak it. And just a thought on the range device...$200 for just that seems pointless when a brand new intune can be had for $380 or less. Diablosport even has a $100 credit right now for turning in an old predator. Turn it off fellas, get your peace of mind.
Appreciate the observations.snowpatrolB said:
Please, keep us up to date with your thoughts about inTune. The reviews I've read have been a little sketchy, but that doesn't mean someone couldn't change my mind.
Another thing to remember is the Diablo folks have been very late to the game, when it comes to transmission tweaks. This could be a good thing, or a bad thing.
Good luck!
Nick
Nick@Night said:
No expert here, either.
Was wondering how easy it is to return the vehicle to stock, using inTune? Do you wade through menus looking for the parmeters that have been changed, or does it remember the vehicles former state? Just curious.
Especially with an older vehicle, like mine, I believe a custom tuner would offer something the hand-helds, don't: They usually take a snap-shot of the vehicles current state, before the tune is written. Among other things, they can find anamolies that should be corrected, before the tune is installed.
Still trying to think it through. Thanks for the feedback.
Nick
Was wondering how easy it is to return the vehicle to stock, using inTune? Do you wade through menus looking for the parmeters that have been changed, or does it remember the vehicles former state? Just curious.
Especially with an older vehicle, like mine, I believe a custom tuner would offer something the hand-helds, don't: They usually take a snap-shot of the vehicles current state, before the tune is written. Among other things, they can find anamolies that should be corrected, before the tune is installed.
Still trying to think it through. Thanks for the feedback.
Nick
I haven't removed the tune yet but the user manual shows it being a one step process...I would also like to look into a custom tune someday just for that same reason of the initial check up of the vehicle but I had to have an immediate solution for AFM it was really wearing on me, and with the intune I guess I could data log and have DiabLew or someone write a custom tune and save it on the device...not sure if I'd get that same diagnostic snap shot or not that way though.
Wearing on me, too. Time to make a decision.
Thanks for your help!
Nick
Thanks for your help!
Nick
Nick@Night said:
Anytime...alot of your posts are what originally brought this matter to my attention, coupling that with my truck's symptoms I was able to pin point this as my problem and I'm just hoping I saved it since I don't know how well the previous owner took care of it...he obviously didn't monitor TSBs lol
EMSDC said:
Quoted is the original post on the AFM - oil consumption issue.
Here's my two cents again...actually up to six cents on this issue because it is really bugging me. After reading many of the posts in this forum on the AFM issue, I traded my cherry fully equipped 2007 for a new 2013 Avalanche, earlier I traded a 2011 Tahoe for a 2012 Avalanche to get more room in the rear seat area. No regrets because I always colored component wanted smoothies anyway. Seems a lot of posters are turning off the AFM feature on older Avys which is probably a wise move to delay or prevent the #1/#7 stuck oil ring/oil consumption issue. That is not an option for me at this time since my vehicles are still under warranty; however since I plan to keep the Avys forever I worry about problems 4-5 years down the road and depending upon future posts and info may have to go that route eventually.
The original post above references a 2011 Avy which may have this issue and I did a little digging to find out just how many years of vehicles may be involved and if the problems were properly identified and eventually solved. I checked out many Chevy Truck and Sierra.Silverado forums and found that there are many posts of TSBs and corporate memos covering the oil consumption/AFM issue. In particular TSB 10-06-011-008 dated 8/24/2010; Bulletin/TSB 10-06-008B dated 3/7/2011 and Corporate Bulleting/Letter to Dealers 0601008G dated 1/3/2013 which is a 2013 issue and the most recent that I could find. All will be listed below. Of particular note is that the problem is also associated with 2010 - 2011 Avalanches built prior to 2/1/2011 the date of the updated valve cover and 10/2010 the date of the AFM shield. I could find no mention of vehicles affected after the 2/1/2011 build date.
On each board there are numerous posts on the issue....the oil consumption issue seems to focus around two points.....PCV valve....seems that on earlier vehicles there was a problem with the location of the PCV valve pickup in the valve cover......modified valve covers were placed on the earlier 2007/08 vehicles to rectify this problem; however I had seen posts where this had been done and owners checked the line going to the intake manifold after the modification and it was still pulling oil....saw a few other posts that said there was a later modification where the PCV valve was removed altogether and a controlled orifice was installed to reduce oil pull through the intake manifold/valves into the combustion chamber. AFM......Then there were posts on the AFM problem and how oil spray discharged from the AFM valve overloaded and clogged the oil rings on the #1/#7 pistons. The posts referenced the dual problem.....doesn't matter if the oil is pulled through the induction system, burned and clogging the compression rings and/or discharges by the AFM valve and by passing clogged oil control rings to get burned in the combustion chamber.....the result is the same....oil will be burned, plugs will foul and the engine will misfire. If this is the case, shutting down the AFM with a tuner will help, but depending on the year and if PCV system modifications were not made, it may only delay the onset of the problem. Of note in the later correspondence was that multiple oil monitoring was no longer required before addressing the problem in faulty engines.
Also noted that there were many owners with high mileage vehicles who had not yet experienced the problem. There were posts by mechanics who have seen a lot of older Avys who blame the problem on extended oil changes calling GMs OLM (oil life monitor) an engine killer some going 12K+ on the oil changes due to the monitor, and that the problems were more frequent in vehicles that did not use synthetic or exceeded 3K-5K oil/filter changes. Others, like GM attributed the increased frequency to driving styles which I guess would have an effect if the AFM is still active.
One thing I did not see mentioned was engine oil pressure. From the day I bought the '07 new it would routinely start at 55-60 psi and level to about 40 psi at warm idle. I thought that was unusual, but the dealer said it was within normal specs. Of course I didn't believe him and drove a few others in the lot and the '07s and '08s ran the same pressures. When I had purchased the '11 Tahoe (manufactured 4/2011), I noticed that it would start at 40-45 psi and level to 25-30 at warm idle....and that is the pressures where the '12 and '13 Avys also run using the same Mobil 1 5W-30. Perhaps there were other engineering changes in later models to address the AFM problem by reducing pressure in the oil galleries to lower AFM valve discharge pressure and volume of oil spray
I wonder if anyone in the forum with high oil consumption are also running at higher pressures with up to 60 psi on startup.Following are the TSB/Correspondence I ran across:
0601008G:
Engine Oil Consumption on Aluminum
Block/Iron Block Engines with Active Fuel Management
(AFM) (Install AFM Oil Deflector and Clean Carbon from
Cylinder and/or Install Updated Valve Cover) (Jan 3, 2013)
Subject: Engine Oil Consumption on Aluminum Block/Iron Block Engines with
Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean
Carbon from Cylinder and/or Install Updated Valve Cover)
Models: 2007-2011
Cadillac Escalade Models
2007-2011
Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe
2010-2011
Chevrolet Camaro
2007-2011
GMC Sierra 1500, Sierra Denali, Yukon Models
2008-2009
Pontiac G8 GT
Built Prior to February 1, 2011 (Updated Valve Cover) and October 2010 (AFM Shield)
Equipped with Any of the Following Engines:
? Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs L94, LZ1,
L99, LC9, LH6, L76, LFA, L92)
? Iron Block V8 Engine with Active Fuel Management (AFM) (RPOs LMG, LY5)
? Hybrid Engine (RPO LFA ? Only Applies to Hybrid Models Built July 7, 2009 February 1, 2011 ? Prior Builds Not Cast For AFM Valve)
Attention: This bulletin does not apply to the Buick Rainier, Chevrolet TrailBlazer and
GMC Envoy equipped with LH6 due to a different design oil pan and AFM pressure relief valve.
This bulletin is being revised to update the Warranty Information. Please discard Corporate
Bulletin Number 100601008F
(Section 06 ? Engine/Propulsion System).
Condition
Some customers may comment about engine oil consumption of vehicles with higher mileage
(approximately 48,000 to 64,000 km (30,000 to 40,000 mi) and a service engine soon light being on
and/or rough running engine. Verify that the PCV system is functioning properly. If the customer
understands that some oil consumption is normal and still feels the consumption level is excessive, more than 1 quart per 2000 to 3000 miles of driving, perform the service indicated in this bulletin. It is no longer necessary to have the customer return multiple times to have the usage verified.
Cause
This condition may be caused by two conditions. Oil pulled through the PCV system or oil spray that
is discharged from the AFM pressure relief valve within the crankcase. Under most driving
conditions and drive cycles, the discharged oil does not cause a problem. Under certain drive cycles
(extended high engine speed operation), in combination with parts at the high end of their tolerance specification, the oil spray quantity may be more than usual, resulting in excessive deposit
formation in the piston ring grooves, causing increased oil consumption and cracked or fouled spark
plugs (#1 and/or #7). Refer to the latest version of Corporate Bulletin Number 120601001.
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If this repair does not correct the condition, it may be necessary to replace all of the piston
assemblies (piston and rings) with new parts. Refer to SI for repair procedure.
------------------------------------------------------------------------------
Bulletin No.: 10-06-01-008B
Date: March 07, 2011
Subject: Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder)
Models: 2007-2009 Cadillac Escalade, Escalade ESV, Escalade EXT 2007-2009 Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe 2007-2009 GMC Sierra 1500, Sierra Denali, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL 2008-2009 Pontiac G8 GT Equipped with Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs LC9, LH6, L76, LFA, L92) with Greater than 45,000 km (28,000 mi)
Supercede: This bulletin is being revised to add the 2009 model year and new Correction information for the 2009 model year - left rocker arm cover replacement. Information has also been added after step 9. Please discard Corporate Bulletin Number 10-06-01-008A (Section 06 - Engine/Propulsion System).
Condition
Some customers may comment about engine oil consumption of vehicles with higher mileage (approximately 48,000 to 64,000 km (30,000 to 40,000 mi). Verify that the induction system is assembled correctly and that there is no evidence that the engine has been ingesting dirty air due to a mis-assembled induction system. Also verify that the PCV system is functioning properly. If diagnostic procedures indicate that oil consumption is piston/piston ring related, verify that oil consumption is less than 3,000 km (2,000 mi) per liter/quart. If these conditions are met and oil consumption is less than 3,000 km (2,000 mi) per liter/quart, perform the service indicated in this bulletin.
Cause
This condition may be caused by oil spray that is discharged from the AFM pressure relief valve within the crankcase. Under most driving conditions and drive cycles, the discharged oil does not cause a problem. Under certain drive cycles (extended high engine speed operation), in combination with parts at the high end of their tolerance specification, the oil spray quantity may be more than usual, resulting in excessive deposit formation in the piston ring grooves, causing increased oil consumption.
Correction
2009 Vehicles Only
Important This left rocker arm cover is NOT to be used on 2007-2008 vehicles because of the calibration of the PCV orifice being different in 2007-2008.
A new left rocker arm cover has been released for 2009 engines. Technicians should replace the left rocker arm cover with GM P/N 12642655. This rocker arm cover has relocated PCV drain holes that prevents PCV pullover into the intake manifold. Refer to SI for Valve Rocker Arm Cover Replacement - Left Side.
2008-2007 Vehicles Only
To correct this condition, perform the piston cleaning procedure as described in this document, and install a shield over the AFM pressure relief valve per the procedure outlined in this document. Monitor oil consumption after this repair to ensure oil consumption has improved to acceptable levels. If this repair does not correct the condition, it may be necessary to replace the piston assemblies (piston and rings) with new parts.
Important It is critical in this cleaning process that the engine/fuel injector cleaner remain in the cylinders for a minimum of 2.5 hours to fully clean the components. The cleaner solution must be removed before a maximum of three hours.
1. Verify the oil consumption concern following Corporate Bulletin Number 01-06-01-011F. If oil consumption is found, continue on with this bulletin.
2. Remove the spark plugs and ensure that none of the pistons are at top dead center (TDC).
3. Clean the pistons by putting 118-147 ml (4-5 oz) of Upper Engine and Fuel Injector Cleaner, GM P/N 88861802 (in Canada, use 88861804), in each cylinder. Allow the material to soak for at least 2.5-3.0 hours, but no more than three hours and then remove the cleaner. A suggested method of removing the cleaner is cranking engine over. Make sure to unplug the ignition coils and fuel injector before cranking the engine over. Also make sure that the painted surfaces are covered so no damage is done.
4. Remove the oil pan. Refer to Oil Pan Replacement in SI.
5. Remove the AFM valve.
6. Install the new shield, GM P/N 12639759, and tighten the AFM valve to the oil pan to 28 Nm (20 lb ft).
Important Ensure that the engine cleaner is thoroughly removed before reinstalling the spark plugs. Failure to do so may result in a hydro-lock condition.
7. Reinstall the spark plugs. Replace the spark plugs if necessary due to full of carbon.
8. Reinstall the oil pan. Refer to the Oil Pan Installation procedure in SI. Replace the oil pan gasket if necessary. Refer to the parts catalog. Replace the engine oil if necessary.
9. Re-evaluate the oil consumption. Document on the repair order. If the oil consumption is still greater than 0.946 L (1 qt) in 3,200 km (2000 mi), replacement of the pistons and rings will be required.
Important Some minor scratches may be noticed on the cylinder walls during piston and ring replacement. If the scratch cannot be felt when running your finger nail over it, the scratch is considered normal wear and the block or engine should not be replaced.
----------------------------------------------------------------------------------
TSB #10-06-01-008:
Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder) - (Aug 24, 2010)
Subject: Engine Oil Consumption on Aluminum Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder)
Models: 2007-2008 Cadillac Escalade, Escalade ESV, Escalade EXT
2007-2008 Chevrolet Avalanche, Silverado 1500, Suburban, Tahoe
2007-2008 GMC Sierra 1500, Sierra Denali, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL
2008 Pontiac G8 GT
Equipped with Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs LC9, LH6, L76, LFA, L92)
with Greater than 45,000 km (28,000 mi)
--------------------------------------------------------------------------------
Condition
Some customers may comment about engine oil consumption on vehicles with 45,000-56,000 km (28,000-35,000 mi) or greater. Upon further investigation, a technician may find that the engine uses 0.946 L (1 qt) of oil in as little as 1,200 km (800 mi). After this bulletin is completed, the vehicle should be driven 3,200-4,800 km (2,000-3,000 mi), then tested for oil consumption again.
Cause
This condition may be caused by an uncovered AFM valve that sprays oil on the bottom of the cylinders when the vehicle is in four cylinder mode. Over time, the rings cannot handle the volume and begin to stick with carbon. At that point, the vehicle oil usage may go up considerably.
Correction
A new AFM shield/ring cleaning process has been developed to restore the function of the rings. If the oil economy has not improved to no more than 0.946 L (1 qt) of oil consumed in 3200 km (2000 mi) after cleaning, it may be necessary to replace all of the pistons and piston rings.
Oh and I almost forgot, here is a copy of an email from GM to their dealers as GM tech document released April 28th 2011, describing the same symptoms showing different solutions than the attachment above.
All seem to be related to the PCV valve. This latest document describes a new and improved PCV valve which requires valve cover modifications to support the newly designed PCV valve but as I've stated, the information is a couple of years old.
#PIP4574M: Excessive Oil Consumption And/Or Blue Exhaust Smoke - Investigation Update
Subject: Excessive Oil Consumption And/Or Blue Exhaust Smoke - Investigation Update
Models: 2007 Buick Rainier
2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe, Trail Blazer
2007-2008 GMC Envoy, Sierra, Yukon
2008 Pontiac G8
2007-2008 Saab 97x
with a 5.3L or 6.0L Aluminum Block V8 Engine
and AFM (Active Fuel Management)
RPOs LC9, LH6, L76, or LFA
--------------------------------------------------------------------------------
This PI was superseded to include revise the affected RPO codes, specify that this is for Aluminum Block Engines only, update models and provide a general update on the status of this investigation in step 5. Please discard PIP4574M.
--------------------------------------------------------------------------------
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may complain that their vehicle has been using approximately 1 quart of oil every 500-1,000 miles. In most cases, the customer will advise that this did not start until the engine accumulated approximately 30,000 miles or more. In some cases, the customer may note that this is more apparent when driving at highway speed. In rare instances, a SES light and engine misfire may be encountered with a P0300 DTC.
Upon inspection, an oil fouled spark plug(s) may be noted. In most cases, static compression and cylinder leakage testing will appear normal. Excessive oil may or may not be found in the intake manifold.
In most cases, this is the result of stuck oil control rings. Generally, the stuck oil control rings are the result of excessive oil on the cylinder walls. The excessive oil can come from the PCV system and/or the AFM pressure relief valve in the oil pan.
Recommendation/Instructions:
If this concern is encountered, follow the steps below:
Visually inspect the entire engine and the underside of the vehicle for any evidence of oil leaks and repair them as necessary.
Inspect the fresh air hose/pipe that is attached to the RF (passenger side) valve cover and all related connections for restrictions, such as plastic casting flash or a pinched hose, and repair as necessary. A restriction in this area may cause excessive crankcase vacuum and oil consumption through the PCV vacuum tube.
If the truck has an engine misfire and a spark plug that is obviously oil fouled, skip to step 4 since this proves that it has an obvious oil consumption concern. If not, perform an oil consumption test as outlined in the latest version of oil consumption of 01-06-01-011 to verify the concern before proceeding to step 4. Allow the vehicle to sit on a level surface with the engine off for at least 10 minutes to allow the entire engine to drain back to the oil pan before checking the engine oil level and adding oil. Compare the oil consumption test results to one of the scenarios below to determine further direction:
? If oil consumption is Less than 1 quart of oil every 2,000 miles and no low oil light has been experienced, no repairs should be performed as this should be considered acceptable oil consumption as outlined in the latest version of 01-06-01-011.
? If oil consumption is Less than 1 quart of oil every 2,000 miles but the customer has experienced a low oil light, refer to the latest version of PIP3959 for a potential low oil light sensor concern.
? If the dealership verifies that oil consumption is More than 1 quart every 2,000 miles, perform the steps below as necessary:
Determine if the engine has been ingesting oil through the PCV system by removing the intake manifold and measuring how much oil can be poured out of the throttle body opening with the throttle body removed. It is normal to get a couple of teaspoons of oil out of the intake. If the engine has been ingesting oil through the PCV system, several ounces of oil will be measured, many times as much as a 1/4-1/2 quart.
? If the engine HAS NOT been ingesting oil through the PCV system, go to step 5.
? If the engine HAS been ingesting oil through the PCV system, inspect the PCV baffle as outlined in the rest of Step 4 below:
4a. Remove the LH (driver's side) valve cover and inspect the PCV baffle drain holes shown below to see if they are plugged with hardened oil deposits. If they are plugged, replace the valve cover, ensure that the customer is changing their oil according to the maintenance schedule in their owner's manual, and re-evaluate the concern. Generally, this would not be a concern until several thousand miles have accumulated.
4b. With the LH (driver's side) valve cover removed, inspect the PCV baffle to ensure that it is properly sealed to the valve cover by flipping it over and adding a little oil to the corner of the valve cover as shown below. The oil should stay in place as shown on the 2 outer valve covers below. If the oil drains into the PCV baffle as pointed out on the middle valve cover below, replace the valve cover. Generally, if this is the cause of the concern, it would have been present early in the life of the vehicle or shortly after valve cover replacement.
Important: If Step 4a or 4b led to valve cover replacement, perform Step 4b again on the replacement valve cover before installing it.
? 4c. If the engine HAS been ingesting oil through the PCV system but the valve cover passed the tests outlined above, the engine may have an over-aggressive lifter that is causing the oil ingestion through the PCV system. Sometimes the lifter may be doing this intermittently so it is not always possible to isolate one by inspecting the lifter flow with the driver's valve cover removed. As a result, it is suggested to replace all 8 of the left/driver bank lifters due to the oil in the intake and re-evaluate the oil consumption concern. The right/passenger side lifters should not cause oil in the intake so there is no need to replace them. If the vehicle returns with excessive oil consumption but is no longer ingesting oil through the PCV system, it most likely has stuck oil control rings as outlined in Step 5.
If the engine HAS NOT been ingesting oil through the PCV system and there are no obvious valve seal concerns, this is most likely the result of the AFM pressure relief valve in the oil pan spraying oil on the bottom of the cylinders when active fuel management is on. This may eventually cause the oil control rings to stick and increase the rate of oil consumption. As outlined in the July 2010 GM STC Service Know-How Emerging Issues Seminar (10210.07D), a related bulletin is going to be released to repair this by cleaning the oil control rings and installing a shield over the AFM pressure relief valve. This bulletin was scheduled for a July 2010 release but the bulletin is still going through the final stages of the release process. At this time, it is on track for a mid-August release date. Once released, you will be able to find the new bulletin in the New Bulletins Section of Service Information and this PI will be updated to include the bulletin number as well.
If you would like to view the July 2010 GM STC Service Know-How Emerging Issues Seminar (10210.07D) mentioned above, you can find it by following this path:
? Go to the GM Training Website. (If necessary, there is a link to this website at GM Global Connect "Dealerworld")
? Enter your Training Person ID and Password.
? Click the "Service Know-How/TECHAssist" Link
? Click the "Emerging Issues" Link
Started to read this but my eyes glazed over. Way too much most likely/certainly rehash to screw with for a Mother's Day weekend.
Thomcat:
My eyes are still open. A very clear, concise, and smooth(ie) summation.
Happy Mother's Day!
Nick
My eyes are still open. A very clear, concise, and smooth(ie) summation.
Happy Mother's Day!
Nick
Thomcat said:
No excessive consumption, yet, but have verified my '08 runs at the higher pressures. I, too, would like to know what was changed in the last few years of the GMT-900. Only thing I'm pretty sure about is the new lifter design.
Wonder if we'll ever be lucky enough to see some photos of the valve cover engineering changes?
Nick
Nick@Night said:
What is considered higher pressures? I am running between 50-55
Once warmed to 210F the '12 and '13 run at 35-40 psi with Mobil 1 5W-30.....idles around 30........max at 65 mph around 2000 rpm at 40 psi (mid gauge)....in the '07 I always felt uncomfortable seeing the voltmeter and temp gauges around 12 o'clock and the oil pressure gauge at 1 to 2 o'clock.
Yeah that's about where my '07 is at 1-2 o'clock and I'm running mobil 1 5-30 with AFM off.
Could be they redesigned the lifters on later models to operate at a lower pressure and a lower set pressure needed to trigger the AFM dump valve to reduce the volume of spray in conjunction with the oil baffle fix in the lower end.
Even if operating with higher pressures.........no AFM, no oil spray......if I still had my '07 out of warranty......I'd shut it off, even IF it did save gas.
Even if operating with higher pressures.........no AFM, no oil spray......if I still had my '07 out of warranty......I'd shut it off, even IF it did save gas.
Thomcat said:
Recall the re-designed lifter was one of the AFM fixes for the early GMT-900's. Would be interesting to see whether the part numbers for the early re-design matched the part numbers for the later numbers.
What accounts for the lower pressures in the later models is the million dollar question, for me.
Nick
Probably the same oil pump, just set the pressure relief valve on the pump to a lower setting change spring on pump if not adjustable.....even so they would likely change the part number.
I remember reading in the '07 shop manual that the AFM system needed minimum 35-40 psi to operate......they could have changed the AFM valve and everything associated with it to operate at a lower pressure. Anything above 20 psi should be fine to lube the engine.
I remember reading in the '07 shop manual that the AFM system needed minimum 35-40 psi to operate......they could have changed the AFM valve and everything associated with it to operate at a lower pressure. Anything above 20 psi should be fine to lube the engine.
Thomcat said:
You made the point about the different oil pressures, before. Didn't make an impression, at the time; however, I wouldn't be surprised if the higher oil pressures contributed to the AFM issues.
Eventually, everything we ever wanted to know about GM's AFM initiative will leak out. (No pun, intended.)
Wonder how old I'll be, by then?
Nick
Nick@Night said:
There definitely seems to be a redesign related to reduced oil pressure. Checked out other Chevy truck forums, e,g, gm-trucks,com, and they seem to experience with lower pressure posts on later Silverados............2011s and later..........warm idle at around 25 psi which climbs to a shade over 40-45 psi at 2000 rpm....exactly what my mine are doing once warmed.
Bassman Z71
Full Member
Just a note, my 2011 sits at 20psi at idle. Maybe gets to 30 or 35 psi at highway, never 40psi. Worries me a little. Have a slight tick, so i use Lucas upper cylinder lube which helps the tick issue.
Bassman Z71 said:
From what I have read the rule of thumb on modern engines is minimum 10 psi per 1000 rpm, so 20 psi at idle (600 rpm) and 38 at 65 mph (2000 rpm) is more than enough and I don't worry anymore....at least for as long as the warranty period.
No doubt lower oil pressure would ease the problems with the AFM system. I always thought the pressure on these trucks was high anyway. Considered it odd/concerning 'til I found out 55/60 was design normal. Most street vehicles I'd driven up until then, at least those with gauges, relieved at around 40 psi. I've always considered high oil pressure to be a bad thing.