Greetings all:
I find it rather laughable when I hear people suggest that the 5.7 Hemi lifter/camshaft failures are a rare thing. It is quite common and getting much worse.
My name is Joseph and I have a 2012 Dodge Ram Hemi 5.7 that started the infamous "hemi-tick" at about 90,000 miles give or take. Since it was under warranty at the time, I took it to the local Dodge Servicing department in Sumter SC. They replaced a coil pack, all 16 spark plugs, and supposedly did an intake induction cleaning and fuel system flush. Total cost to me was $988 bucks. That's the most expensive tune-up I've ever seen, especially considering the same services were advertised on their own board for about $300 bucks. Personally, I suspect they did more than that and it's my suspicion that changed out a bad lifter despite the possibility of a bad camshaft lobe. They knew our warranty was about to expire so they did the bare minimum to turn the truck back out to me with the hidden repair they did. I know that Chrysler is telling their service departments to hide the camshaft lifter failures if at all possible in order to minimize public awareness.
To get to my point, at about 104,000 miles, the "hemi-tick" came back and eventually turned into a loud knock. Since the warranty was expired, I tore into the engine myself (I'm a retired AF aircraft mechanic), 36 years of automotive repair, and even paint and body repair. So my mechanical skills are not lacking to say the least, without which I would not have been able to sustain my 1999 Chevy Suburban 5.7 Vortec for as long as I have, and still running strong. Sure she's needed work along the way, but she still goes strong. Just for giggles and fun, I pulled the Suburban's engine 3 years ago and did a complete overhaul, bottom and top. The rings were still solid, cross-hatches still visible, and no ridge around the bore-tips. And the camshaft and lifters looked beautiful, despite neglected oil changes (on the Suburban) at times, and about 225,000 miles. The only degredation I noted were my intake and exhaust valves which were all pitted, so I replaced the valves and lapped them in my garage. To-date, 297,000 miles on my baby and she's still pulling roughly 6,000 pounds of horse trailer (with horses).
I can't say that for my Ram. With only 114,000 miles, the #8 cylinder lifter was destroyed and the roller and needle bearings were missing. Naturally I've got to drop the oil pan to remove all possible debris. Cylinder's 4 and 6 MDS lifters were also damaged as each of its rollers were severely chaffed. I noticed that both MDS lifters for 4 and 6 were not appropriately locked on center as the lock-tabs were twisted to the side, thus causing the rollers to spin somewhat at an angle. This no doubt caused the damage to the lifter rollers for cylinders 4 and 6. Cylinder number 8 however was completely dry with little to no oil, and it's roller is toast, and the camshaft lobe for all 3 cylinders mentioned (passenger side) are destroyed.
WHAT'S CAUSING THE PROBLEM?
This is something I've yet to see anyone explain. Mind you I am a [censored] good troubleshooting mechanic (all thanks to the USAF), and here then is my diagnosis. MDS lifters require oil pressure to expand into the locked position. This temporarily robs the oil supply volume just long enough to lock the lifters into place. Once locked, oil pressure is dispersed evenly respective of the applicable lubed component of the engine. Unfortunately, when you have 1 or more MDS lifters failing to lock, oil pressure is lost to the rest of the engine (not all pressure but enough to cause oil starvation). This would explain why the intake lifters for cylinder's 2 and 8 were nearly dry, while cyilnder's 4 and 6 intake MDS lifters were saturated with oil since both of these lifters failed to lock. When an MDS lifter fails to lock due to internal failure of the PLASTIC (did I mention plastic?) keepers, oil pressure continues to attempt to lock the lifter, which of course never happens due to the failure, and this robs the engine of oil to the rest of the valve-train. Lifters that fail to lock also cause the infamous "Hemi-tick". So NO the Hemi-tick is not a good thing and NO it is not normal.
SOLUTION:
Dump the MDS system. This requires camshaft replacement-upgrade to a non-MDS system, installation for solid lifters with heavier duty rollers, removal and plugging of the MDS oil solenoids, and a PCM flash for MDS deactivation. The 5.7 Hemi is a rather easier engine to work on. I found the fan-clutch to be a little more difficult to remove than usual; that is until I realized that after 2007 (or 2009), the fan clutch is not leftee-loossie, righty-tighty, but rather righty-loosie and lefty-tighty. The rest is not that difficult. You will likely find the exhaust manifold heat-shield bolts broken. I suggest not putting that wasted product back on. Switch out to headers if you choose, or simply leave the exhaust manifold exposed. There is nothing nearby that will be damaged from heat. The driver side exhaust manifold is a little bit pesky to takeoff due to the steering column shaft. Or better yet, leave the exhaust manifold on the heads and disconnect the exhaust pipes from the manifold. I chose to remove them in case my heads needed to be worked.
Summary: The MDS lifters are failing to lock and robbing the engine of oil pressure. This is especially worsened by those who might have a nasty habit of idling the engine too long. The loss of oil pressure, especially at idle, causes oil-starvation to the rest of the valve train of the specific bank (1 - driver side / 2 - passenger side) and causing the lifters to fail at the rollers. Once the rollers are damaged, the camshaft lobes will eventually be wiped out. Lastly, I will not be using 5W-20 as the dealership has been using, and yes (for the record), we've maintained appropriate oil-change maintenance, and yet still suffered catastrophic failure. I will be switching over to 5W-30 synthetic once I've completed the upgrade.
I hope this helps anyone else out there. You do not have to agree, but I'm almost certain my prognosis is 100% percent correct. The dry #8 lifter caused by lost oil pressure due to lifters 4 and 6 MDS lifters hogging oil pressure, is clear indication of what's causing the lifter rollers to fail, and thus leading to unfortunate camshaft destruction. #8 lifter was destroyed due to oil-starvation, and lifters 4 and 6 were damaged due to failing to lock on-center leading to excessive oil supply attempts at locking the lifter into place.