Originally Posted by OVERKILL
Originally Posted by JosephA
Update:
The MDS Delete kit has been ordered. Only time will tell.
On a side note, GM recognizes the same issue, and has released this information. It is clear that GM seems to care about their customers and product owners. I wonder when Chrysler is going to step up and do the same. As suspected, GM also believes their AFM lifter failures are a result of oil pressure issues and likely improper AFM deactivation/reactivation timing. Here is their release:
TECHNICAL BULLETINwww.melling.comMelling Engine Parts, P.O. Box 1188, Jackson, MI 49210 GM LS AFM Deactivation LifterIssuesWehave 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 issuemay not have been corrected. Most lifters returned for analysis are found to be good. We have found that most lifter faultsare 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 inletoil 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 oilpressure relief valve. At low enginespeeds the low side of the operating range will depend on the engines ability to produce oil pressureusing 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 engineswith 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.
What say you Chrysler? Still blaming the lifter failures on bad batch's or customer neglect?
Joe
That quote is from Melling, not GM, FWIW:
https://www.melling.com/wp-content/...-Deactivation-Lifter-Issues-3.1.18-1.pdf
Seems consistent with what we are discussing here for the most part, though I'm not sure if Chrysler uses a screen to block contamination from the MDS passages. If there is one, you'll likely discover it during your repair. I could certainly see the activation of the system while on the ramp could be problematic, though on the Chrysler setup, with the location of the orifice that feeds the MDS port, I cannot see it engaging with any significant lift as:
1. The pin should not be able to displace with significant pressure on it, so it would have to come back to, or close to, base circle before there was low enough pressure
2. The orifice needs to align with the cut-out in the lifter body where the MDS pressure port is located, which should be blocked by the lower portion of the lifter body upon any significant lift.
The oil pressure issue discussed in the linked article isn't about insufficient lifter lubrication, which was the general concern in this thread, it was insufficient engine oil pressure to cause the MDS lifters to operate properly, which could be due to:
a. Worn lifter bores, bleeding off too much pressure so the pin stays locked
b. Worn engine, resulting in insufficient global pressure so the pin stays locked
c. Plugged or partially plugged AFM screen preventing sufficient pressure from reaching the lifters, so the pin stays locked
I think the TSB is generally good advice though.
No matter how you look at it, it all comes down to simply thought. Did Hemi engines suffer catastrophic lifter failure prior to MDS? As I've stated before, the answer is no. They have valve seat issues which was easily corrected with proper machining.
In the same way, did GM have lifter failure prior to the AFM system? The answer is no; the LS engines are a fantastic design despite a short history of initial piston slap issues due to excessive gaping between the rings and the cylinder bore. Both the early Hemi engines and the LS engines were great products. But as soon as both decided to again try cylinder deactivation technology, we are again seeing lifter destruction. Catalack tried this in the 1980's and suffered engine problems then.
The solution is simple. Delete MDS and the problem is solved. While there may have been a few Hellcat engines suffering lifter failure, the problem in my opinion is incorrect lubrication for an engine with such high horse power. You can't build a high performance engine using non-weighted engine oil. Could you imagine what would happen to dragsters if they ran their engines on 00-20 non-weighted oil? BOOOOM!
The problem is oil...contributing to early failure of weak design lifters, which in turn wipes out the cam lobes.
Dump MDS and AFM, go back to standard/traditional engine oil, and the problem is solved. Who gives a crap about the EPA's CAFE standards. I didn't buy the truck to save gas; I bought it do hall trailers and horses. And you can't do that driving a 6 cylinder Japanese engine.
The lifter bore is not the cause of the issue or all of them would be failing. It is possible the cam journals might have been damaged, but I believe I caught the problem early enough so as to avoid major engine damage.
I installed the cam and lifters 2 days ago. But I freaking forgot to drill out the two broken bolts on the driver side head. So now I have to remove the head again to drill out the stuck bolts and tap-die the hole.
The ultimate goal of course is to fix the truck, and dump it; let it become someone else's problem. Rest assured, I will never buy another Dodge product again....NEVER. I've been hosed by that creepy company twice before despite religious oil changes and proper maintenance. You just can't win owning a Dodge. I'm sticking with the more dependable Toyota's and Honda's; at least they honor their warranty unlike Chrysler.
Joe