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Hal, Chevy Master Tech
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Experience:  ASE and Chevy Master , 31yr Dealership exp,
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Chevrolet C 1500: I have a 2007 5.3 ,Vin code M, a lifter

Customer Question

I have a 2007 5.3 ,Vin code M, a lifter collapsed .I went in replaced all the lifters,had a valve job done on the heads. I put it all back together .It has a loud pop when you first start it ,sounds like it is running on 4 cylinders. I checked the compression ,cylinders with the fuel management solenoids have 35 lbs less than the others.Any advice?
Submitted: 2 years ago.
Category: Chevy
Expert:  Hal replied 2 years ago.

Hi my name is XXXXX XXXXX Your complete satisfaction is my goal. Please provide as much information about your concern as you can.

 

There is a bulletin that deals with this concern. When a AFM lifter collapses the VLOM assembly should be replaced, along with the lifter guides. Check the screen that is under the VLOM ( valve lifter oil manifold) oil sending unit. It may be plugged or slightly restricted.

Here is the bulletin PIP 456K.

 

Condition/Concern:

 

Some customers may comment on an SES light, engine misfire on cylinder 1, 4, 6, or 7 and/or tick noise.

This may be the result of an AFM lifter that unlocks as soon as the engine is started or one that is mechanically collapsed/stuck all of the time.

If an AFM lifter unlocks as soon as the engine is started, low compression will be found on that cylinder during an AFM compression test, along with a SES light, DTC P0300, and engine misfires on the related cylinder but it is unlikely that any noise will be experienced.

If an AFM lifter is mechanically collapsed/stuck, low compression will be found on that cylinder during an AFM compression test, along with a consistent valve train tick noise, SES light, DTC P0300 and engine misfires on the related cylinder.

Recommendation/Instructions:

 

If SI diagnosis does not isolate the cause of this concern, perform the following diagnostic steps as necessary:

1. Perform a Cylinder Deactivation (Active Fuel Management) System Compression Test in SI. If the running compression of the misfiring cylinder stays below 25 PSI regardless of the AFM solenoid being commanded on or off, an AFM lifter is mechanically collapsed/stuck or unlocking as soon as the engine is started.
2. Perform the Cylinder Deactivation (Active Fuel Management) Valve Lifter Oil Manifold Diagnosis and Testing in SI. If the test above isolated a possible AFM lifter concern, it will lead to this test, which tests the VLOM (Valve Lifter Oil Manifold) for proper operation. SI states a limited amount of air will leak from the bleed holes and outlet ports even when the solenoids are off, compare the amount of leakage to verify all 4 solenoids are operating the same. If it isolates a concern with the VLOM, replace it and reevaluate the concern.
3. The AFM lifters can also be monitored for proper operation by carefully inspecting the cylinder 1, 4, 6, and 7 rockers and valves while cranking or briefly running the engine with the valve covers removed in the service bay. If the valve(s) of an AFM cylinder stop moving while doing this test, the AFM lifter is causing the concern.

Notice: If SI diagnosis or any of the steps above indicate that any AFM lifters are unlocking or collapsed as described above, follow the applicable notes below and replace the VLOM, all AFM lifters, and all plastic lifter guides.

On the 2008-2009 Pontiac G8, 2010-2011 Camaro, and 2007-2010 Full Size Trucks with AFM, also determine if the AFM pressure relief valve shield that is listed in the latest version of 10-06-01-008 has ever been installed for anything else. If not, remove the oil pan and install the AFM shield. If the shield has been installed before, disregard this step. Due to oil pan differences, this shield will not fit Passenger Cars with the LS4 engine or Mid-Size Utility Vehicles with the LH6 Engine. It is also important to thoroughly clean the inside of the oil pan while it is removed.

On the 2007-2009 Chevrolet Tahoe with the Police Package, also reprogram the ECM with the latest calibrations. This only applies to Police Vehicles.

Carefully inspect the camshaft lobes through the lifter bores with a pen light or bore scope to ensure that they are not obviously worn. Also inspect the lifter bores for any obvious scoring/damage that could be a concern.

When reassembling, ensure that the lifters are properly aligned to the new plastic lifter guides before they are installed. If they are not aligned properly, it may damage the plastic lifter guide once it is torqued, which may allow the lifter to turn in the guide.

Clean out the related lifter control oil passages (item 1 below) while the old lifters are removed. Generally, it is only necessary to blow through the passages with shop air but if a lot of debris is noted, it may also be necessary to flush the passages out with brake cleaner. The oil should be changed after doing this since the cylinder heads will be off to replace the lifters anyhow.

Low oil pressure to the VLOM can also cause AFM lifter damage. As a result, it is suggested to note the Tech 2 oil pressure parameter at a hot idle. This is located in the Cylinder Deactivation Data List of the Tech 2. Generally most known good vehicles will have around 30 PSI (207 KPA ) of hot idle oil pressure with new engine oil. As long as there are no oil pressure sensor DTCs, such as a P0522 or P0523, the oil pressure sensor is fairly accurate. If the sensor reads 19 PSI (131 KPA) or less while at a hot idle with new oil, also perform the Cylinder Deactivation (Active Fuel Management) Oil Pressure Relief Valve Diagnosis and Testing as outlined in SI and repair as necessary. In some cases, the new VLOM could correct a low oil pressure concern if there is an internal leak or plugged VLOM filter screen.

 

Hal

Hal, Chevy Master Tech
Category: Chevy
Satisfied Customers: 1020
Experience: ASE and Chevy Master , 31yr Dealership exp,
Hal and 6 other Chevy Specialists are ready to help you
Customer: replied 2 years ago.
Hi,
I replaced the VLOM as recommended ,there was no change.
Is there any re-learn procedure that I must do after everything that has been done .I really don't see how it could be anything mechanical.
After I had ran the engine up to 210 degrees ,I removed the valve covers.I restarted the engine ,# 1,7and 6 intake rockers would stop as soon as engine started.
Before I replaced the lifters ,engine was running fine ,just loud tap from #1 intake lifter.
Thank you for your time
Expert:  Hal replied 2 years ago.

Well you kind of jumped into this repair with out knowing about this bulletin. Thats not your fault, but there are some important things that the bulletin points out. Contamination of the oil passages is the main cause for the solenoids to fail and cause the lifters to unlock. Diagnosis needs to begin with the testing of the components, and then isolating the affected cylinders. With out a tech 2 scanner or one that can read the information for the AFM system it would be difficult to do some of the test.

As the bulletin above states, the oil bores should be cleaned out with compressed air, while the lifters are removed. There could still be some debris that is in the oil galley, and causing the VLOM assembly to fail. Electrical connections and or wiring to the VLOM assembly could also be causing trouble. ( is it setting any codes???, they need to be diagnosed) Was the camshaft lobes inspected?? we have replaced allot of camshafts lately for lobe failure. This is where contamination could come from.

 

The first time I ran into one of these concerns, I only replaced the affected lifter. ( my mistake) I soon learned I needed to completely follow the recommendations in this bulletin to completely diagnose and repair the vehicle. I did end up replaceing the cam, lifters , VLOM, and lifter guides, and removing the oil pan and installing a deflector shield on the AFM oil relief valve that is in the oil pan.

 

You may not have the exact concern, but it does sound like there may still be some contamination floating around in the oil galleys sticking your lifters.

 

As far as I know the reprogram only applies to police package vehicles. But it is always a good Idea to have the latest program installed that is available. Not all updates are published in bulletins . Many corrections are usually combined into new updates, and you usually don't know until it is hooked up to GM and the current avalible program comes up on screen.

 

Here is the key statement in the bulletin .

 

The AFM lifters can also be monitored for proper operation by carefully inspecting the cylinder 1, 4, 6, and 7 rockers and valves while cranking or briefly running the engine with the valve covers removed in the service bay. If the valve(s) of an AFM cylinder stop moving while doing this test, the AFM lifter is causing the concern.

 

Notice: If SI diagnosis or any of the steps above indicate that any AFM lifters are unlocking or collapsed as described above, follow the applicable notes below and replace the VLOM, all AFM lifters, and all plastic lifter guides.

.

If you need more info please ask.

Thanks Hal

Customer: replied 2 years ago.
Hi,
First of all,when I removed valve covers ,heads,VLOM and lifters , all parts were remakably clean to my surprise.The engine has 147000 miles on it..I was really shocked at how clean everything was.
I did replace all the lifters,too much work to have to do it twice.I carefully inspected the lobes on the cam,as good as possible in the engine.I 've had experience with wiped out lobes,big block chevys with solid lift cams.
As I said ,the number 1,7 and 6 intake rocker stops right after start up,with valve covers off.
Is there any method to clean a lfter,or does it have to be replaced?
It is crazy it runs perfect for about 2 to 3 seconds then goes to hell.
Will the Motis system [I think thats it] read this system? If so,can you tell me where to start?
Expert:  Hal replied 2 years ago.

I don't doubt that the engine is clean. The bulletin walks you through all the steps needed to identify the cause. when it talks about cleaning it is talking about the lifer oil bores.

 

"

Clean out the related lifter control oil passages (item 1 below) while the old lifters are removed. Generally, it is only necessary to blow through the passages with shop air but if a lot of debris is noted, it may also be necessary to flush the passages out with brake cleaner. The oil should be changed after doing this since the cylinder heads will be off to replace the lifters anyhow."

 

The information above is what the bulletin recommends.

 

The information below pertains to verifying oil pressure to the VLOM assembly. There is a pressure relief valve in the oil pan. If this valve is faulty you will have low oil pressure to the VLOM assembly..

 

"

Low oil pressure to the VLOM can also cause AFM lifter damage. As a result, it is suggested to note the Tech 2 oil pressure parameter at a hot idle. This is located in the Cylinder Deactivation Data List of the Tech 2. Generally most known good vehicles will have around 30 PSI (207 KPA ) of hot idle oil pressure with new engine oil. As long as there are no oil pressure sensor DTCs, such as a P0522 or P0523, the oil pressure sensor is fairly accurate. If the sensor reads 19 PSI (131 KPA) or less while at a hot idle with new oil, also perform the Cylinder Deactivation (Active Fuel Management) Oil Pressure Relief Valve Diagnosis and Testing as outlined in SI and repair as necessary. In some cases, the new VLOM could correct a low oil pressure concern if there is an internal leak or plugged VLOM filter screen."

 

GM came out with a shield that is installed on the relief valve, but this shield was only to deflect the oil for high oil consumption. Check the oil pressure with a scan tool to verify what the oil pressure is as per the bulletin above.

 

If the lifter is stuck then it will have to be replaced. If it is just unlocking thee still could be a restriction in the passages. The lifter unlocks by applying pressure through the passage from the VLOM to the lifter. It pushes the pins on the side of the lifter in to unlock it and allow it to move up and down with out moving the internal part of the lifter.

 

This passage needs to be inspected. Also I would test the VLOM assemble to make sure you received a good component. Just because it is new does not mean it is good.

The dealership has a tool to verify the VLOM is operating and is not leaking.

 

I as i said above , I know what your going through. Every one has gone through this if they have worked on one of these engines for the first time. The camshafts are coming apart on these engines and it is difficult to see the pitts at times without removal of the cam. They don't go flat like the older cams did. They just start to delaminate .

 

Here is a picture of the block indicating the passage I am referring to.

 

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I am not familure with the modis. At the dealership we use the Tech 2. The bulletin is referring to using this scan tool for diagnosis. You would just have to see if the information is in the modis to perform these test.

 

 

Here is a picture of the AFM relief valve in the oil pan and a picture of the shield installed.

 

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Here is just a paragraph from bulletin PIP4138K doc # 2563016 It explains the cam inspection difficulty.

 

If the tests above do not isolate the cause of this concern, it may be necessary to visually inspect the lifter rollers and cam lobes for obvious damage, such as flat spots, pits, grooves, scoring, gouging, flaking, rusting, etc...It is very easy to overlook a damaged cam lobe when inspecting them through the lifter bores and just because the lifter rollers are not worn, does not mean that the related cam lobes are okay. Both pieces need to be carefully inspected. It may help to use a bore scope or pen light when inspecting the cam lobes through the lifter bores. In some cases, the worn cam lobe may not be discovered until the camshaft is physically removed from the engine and inspected for the issues mentioned above.

 

 

Let me know if this is making sense to you , or if you need further information.

Hal

Customer: replied 2 years ago.
Hi,
It all makes sense,don't know why they have to complicate it so much .I had a 99 Z-71 with the 5.3 ,mileage was about the same.
I appreciate your time ,I'll let you know the outcome.
Thanks!
Expert:  Hal replied 2 years ago.

I don't know why either . I wish GM would come out with a program to disable this system. I wish you good luck and hope you resolve the issue without too much difficulty. Let me know.

 

Hal

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