Originally Posted by LubricatusObsess
Never heard of it. The failure they had was pumping oil past the rings on the 5.3L. I know - I had one. I ran an oil cleaner through it, which cleaned up the rings and slowed the oil consumption, and traded the P.O.S. in. It was a combination of cold AFM cylinders and slppy power cylinder package - NOT the same as HEMI MDS lack of lubrication. Not even close.
Do you actually read the threads you reply to or is this your style, dropping in with some shot-from-the-hip garbage?
From this thread:
https://www.bobistheoilguy.com/foru...c-lifter-failure-oil-related#Post5122957
Originally Posted by Melling
TECHNICAL BULLETIN
www.melling.com
Melling Engine Parts, P.O. Box 1188, Jackson, MI 49210
GM LS AFM Deactivation Lifter Issues
We have noticed an increase in the issues surrounding the replacement of deactivation lifters in GM LS engines with Active Fuel Management or AFM. After installing new lifters the original issue may not have been corrected. Most lifters returned for analysis are found to be good. We have found that most lifter faults are caused by oil pressure issues, or control issues.The AFM activation and deactivation is controlled by the Valve Lifter Oil Manifold or VLOM. The VLOM consists of 4 electronically operated solenoids and is bolted to the top of the engine block beneath the intake manifold assembly. Its job is to direct the flow of pressurized engine oil to the active fuel management intake and exhaust valve lifters. VLOM applies pressurized oil to the AFM lifters when cylinder deactivation is requested, and shuts off that supply of oil to reactivate those cylinders. Cylinder activation and deactivation are both supposed to occur on the base circle of the cam lobe, making the transition from four to eight cylinder mode unnoticeable to the driver. To control contamination a small replaceable oil filter is located in the VLOM inlet oil passageway. The AFM oil pressure relief valve regulates the oil supplied to the VLOM and is located in the oil pan near the oil filter housing. The AFM system has an operating range from 27 PSI to 66 PSI of oil pressure. At higher engine speeds the high side of this operating range is controlled by the AFM oil pressure relief valve. At low engine speeds the low side of the operating range will depend on the engines ability to produce oil pressure using the flow of oil from the oil pump.The AFM lifter bores in these engines have a spec of .843-.844, and the deactivation lifters require 22 PSI of pressure to release the locking pins. Taking these two things into consideration a lifter bore that is even slightly worn could bleed off enough oil pressure to prevent the lifter from unlocking. In addition it has been reported that it is common to find the VLOM oil filter plugged and needing replacement on high mileage engines with miss-fire fault codes. Melling has received AFM DEAC lifters back for warranty claims where the lifter has been stuck compressed, this condition can be caused by the VLOM commanding activation or deactivation at the wrong point in the cam's rotation, either in the ramp, or at the lobe peak.Any time an engine has failed AFM lifters the lifter guides must be replaced, the lifter bores must be measured, and the VLOM must also be tested for proper operation, or replaced.In addition the VLOM oil filter must be replaced as well.
Here's another thread on the subject:
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4629660/1
Quote from the thread:
Originally Posted by clinebarger
Originally Posted by das_peikko
Originally Posted by clinebarger
I do about 1 of these a month on average, Annoying ticks, Misfires & oil consumption are eliminated!!
How often do you see destroyed camshaft lobes from the AFM lifters, which are collapsed, bouncing up and down between the camshaft lobes and the pushrods?
Not many at all..... I see MORE Non-AFM lifters damage camshafts! Keep in mind that AFM lifters have damper springs on them that keeps the lifter "roller" in contact with the lobe even if they fail/collapse.
There are many myths about AFM....
*Oil Pressure is applied to a separate camber in the lifter that forces the plunger to collapse. Many believe the "Pump-Up/Lash control" oil is cut-off to the lifter....Not True.
And another thread:
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4058530/all/5.3_freshly_rebuilt???
Quote from the thread:
Originally Posted by clinebarger
AFM Lifter Failures are quite common, It is not a oil related failure, They fail just the same on spotless well maintained engines & Varnished abused engines. Cylinders #1/#4/#6/#7 have the AFM lifters, It is ALWAYS one of those cylinders with issues!
My shop does several AFM/DOD deletes a year on 5.3L/6.0L/6.2L Gen IV engines, Trucks/SUV's are TOO EASY! A good Tech can do it in 8 hours, To bad GM dealers have no interest in fixing these engines.
And another non-BITOG thread:
https://grassrootsmotorsports.com/f...e-in-seattle-is-the-dealer/118452/page1/
Google is your friend.