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Unlocking lifter.....VLOM problem?


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On 12/29/2016 at 4:18 PM, Ryan Bokros said:

Ok, new guy here! So I know that there is and has been a ridiculous ongoing issue with the AFM lifters sticking or collapsing entirely and all that mess. I have a 2007 GMC Sierra 5.3 Flex Fuel 4X4 - 160k miles. Pretty regular maintenance, I am not OCD, but I try to do my best at around 3500-400 miles - full synthetic Mobile 1 oil, AC Delco Filter, every other change gets a half quart of MMO.

 

 

 

 

Here is my situation....

 

 

 

 

 

No ticking whatsoever (which I know is usually attributed to this), BUT recently a terribly bad misfire on Cyl 4 (one of the AFM cylinders) and throwing the typical 304 code with stabilitrak warning. Before pulling the valve covers, I checked EVERYTHING (well, except compression, should have done that) - I checked plugs (a little black, but not wet), coils, injectors, fuel and oil pressure, etc. That is what led me to go ahead and pull the valve covers to check for any slack in the rockers/valves due to a collapsed lifter (even though there is no noticeable tick). Initially pulling the covers, I was pleased with how clean everything was....and how tight everything was. No slack in the rockers whatsoever, from what I could tell the valve springs look good, etc!! Yay...but WTF is causing this?

 

 

 

 

 

Well, I fired up the truck and found that the intake valve in cyl 4 was not moving. BUT...when my wife got home, I had her turn the engine over for me so I could see it all without doing it myself. Here is what I am confused about - on start up, the valve moves...once maybe twice, it goes through the whole compression cycle then stops once the engine is running...when the engine it turned off, it does the same thing - one or two cycles. If it was collapsed or busted, it wouldn't push the valve at all, would it? Could this be the VLOM and not the lifter? My oil pressure reads well, so I am not experiencing low pressure like others I am reading, but I am aware of the filter leading to the VLOM...maybe that is the next step. Thoughts?

 

 

 

 

 

Thanks!!

 

 

 

 

i have a 2007 gmc yukon xl 1500 flex fuel and i am having the same exact problem as you down to the T.  my #4 cylinder is doing the same exact thing yours was doing and im am wondering if you ever found out what was the cause of the problem. i really hope you still visit this site because i really need an answer on this one. Thx.

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30 minutes ago, rellgmc said:

i have a 2007 gmc yukon xl 1500 flex fuel and i am having the same exact problem as you down to the T.  my #4 cylinder is doing the same exact thing yours was doing and im am wondering if you ever found out what was the cause of the problem. i really hope you still visit this site because i really need an answer on this one. Thx.

When the solenoids in the VLOM begin to fail, they get out of time causing the lifters to collapse at inopportune times.  The AFM system likes clean oil and no additives, that fella was adding Marvel Mystery Oil which is a no no in AFM engines.

 

The VLOM was updated to a new design several years after yours was built as were the lifters and driver's side valve cover (oil consumption).  You can change the VLOM before replacing the lifters but have to weigh time versus money and effort for your situation.

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i have a 2007 gmc yukon xl 1500 flex fuel and i am having the same exact problem as you down to the T.  my #4 cylinder is doing the same exact thing yours was doing and im am wondering if you ever found out what was the cause of the problem. i really hope you still visit this site because i really need an answer on this one. Thx.

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43 minutes ago, swathdiver said:

When the solenoids in the VLOM begin to fail, they get out of time causing the lifters to collapse at inopportune times.  The AFM system likes clean oil and no additives, that fella was adding Marvel Mystery Oil which is a no no in AFM engines.

 

The VLOM was updated to a new design several years after yours was built as were the lifters and driver's side valve cover (oil consumption).  You can change the VLOM before replacing the lifters but have to weigh time versus money and effort for your situation.

Thx for responding so quickly. i have already replaced the lifters and have put the engine back together and everything. i also changed spark plugs, wires, coils, and fuel injectors, and still i have a misfire on #4 cylinder.  So i removed the valve cover and cranked the engine and thats the only cylinder that is not working.  So you think its the vlom........I sure hope so......thx for helping me out.  ill see about changing it today or tomorrow. my wife is so aggravated right now with this truck lol.

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19 hours ago, rellgmc said:

Thx for responding so quickly. i have already replaced the lifters and have put the engine back together and everything. i also changed spark plugs, wires, coils, and fuel injectors, and still i have a misfire on #4 cylinder.  So i removed the valve cover and cranked the engine and thats the only cylinder that is not working.  So you think its the vlom........I sure hope so......thx for helping me out.  ill see about changing it today or tomorrow. my wife is so aggravated right now with this truck lol.

You're welcome.  I'm not certain as I'm not there to test it but it is the usual culprit and is SOP to replace when doing the lifters.  Stick with a GM VLOM, the Dorman ones do not last.  Keep us posted.

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  • 2 weeks later...

ok man i order a GM vlom and i have replaced it. i havent gotten a chance to put it on a diagnostic tool but it is still doing the same thing.  when i took it for a drive the check engine light is still flashing like is was doing before. i was wonder if this is one of those situations when i need to take the vehicle to the dealership shop so they can delete the code with their special tool. 

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On 2/29/2020 at 5:17 PM, rellgmc said:

ok man i order a GM vlom and i have replaced it. i havent gotten a chance to put it on a diagnostic tool but it is still doing the same thing.  when i took it for a drive the check engine light is still flashing like is was doing before. i was wonder if this is one of those situations when i need to take the vehicle to the dealership shop so they can delete the code with their special tool. 

Where in Louisiana are you?  Have you done a compression test on that cylinder or stuck a borescope camera down the spark plug?  Do you have a bi-directional scan tool?

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I am in marrero, Louisiana and no I have not done any of that. I'm going to take it to a shop that I believe will do that.....idk what the problem is......I have done all I know how to do lol .......

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2 hours ago, rellgmc said:

I am in marrero, Louisiana and no I have not done any of that. I'm going to take it to a shop that I believe will do that.....idk what the problem is......I have done all I know how to do lol .......

I know a guy up near Baton Rouge that's good with engines, private individual, not a shop.

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  • 3 weeks later...

Sorry im late to the topic but i have an 08 Impala SS that does the same thing. Stabiltrac and Traction Control light came on along with the Cyl. 4 misfire code. I replaced the lifter twice along with the VLOM and deleted the AFM in HPTuners. I have found that if the #4 lifter has already started to fail before showing any problems it will cause the Camshaft lobe for that lifter to begin to flatten. This is because the valve lifter oil manifold is faulty and spin the lifter 180 degree(Lifter will be spun around). This causes the camshaft lobe to flatten. I also think that the lifter trays has something to do with this as well but I cant remember but I would replace those as well. If you can, pull the cam out and see if any lobes are flat and if not make sure you soak the AFM lifters in 5w30 oil before reinstalling. Hope my response helps

Edited by 20Silverado13
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  • 1 month later...

Rellgmc,

were you ever able to figure out this problem? I have a 2008 GMC Sierra 1500 5.3 and I have a 6 cylinder valve sticking. When you start the truck it will start to move but after 3 or so times it’ll stop and stick. I replaced the VLOM and no change at all. 

Edited by AlecT23
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  • 4 weeks later...

good day, I have a problem with my gmc sierra denali 2015, in the last year the cylinder 7 liffter has been damaged three times, I am from Mexico and I no longer trust the repairs we are doing, what do you recommend? Should I change the VLOM? Would it avoid damage if I cancel the VLOM with the RANGE device?

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On 6/13/2020 at 5:14 PM, Ivan Chavarria said:

good day, I have a problem with my gmc sierra denali 2015, in the last year the cylinder 7 liffter has been damaged three times, I am from Mexico and I no longer trust the repairs we are doing, what do you recommend? Should I change the VLOM? Would it avoid damage if I cancel the VLOM with the RANGE device?

Changing the VLOM is standard operating procedure when replacing a lifter.  It is the failure of the VLOM, the mis-timing of the solenoids, that jams the lifters.  Run Dexos approved oil and keep clean oil in the engine, 7500 miles is too long.

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  • 2 months later...

Has anyone found solutions? Mine is 2013 silverado 5.3l. Random misfire on all 4 AFM, CEL on STabletrak anf Traction control.  Shop says #4 is the main problem. The truck was skippin and jumpin. I have tried workin on it over last 8 months, new plugs clean throttle body. It has sat in garage for 6 months and battery died. I jumped it off, put some seafoam directly in oil. Odd thing to me is, the truck was running perfect. No dash lights. So I drove it for about 30 miles with no problems at all. Come home parked it. Changed the dirty seafoam oil the next day. Started it up the CEL , traction and stabletrak is on again. I disconnected neg terminal to drain the battery. Started it up and ir ran perfect for 10 miles. Shut it off and started it and once again the dash lights are back on??

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