Originally Posted by JosephA
Greetings everyone!
Well after about a year of repairing my 2012 Dodge RAM Hemi, it appears the lifter failure is happening again after driving about 50,000 miles since the repair. As a reminder, here is what I did:
1. Replace camshaft to non-MDS cam made by CompCam.
2. Installed MDS plugs to stop oil flow since MDS was deactivated
3. Reprogrammed ECM to deactivate MDS
4. Installed new Hellcat lifters
5. Replace Bank2 valve-train roller-rocker rails (worn from valve loose valve lash)
6. Initially used Redline 5W-30, but due to excessive costs, I switched to royal purple 5W-30 during the winter, and 5W-40 for summer.
The sound is again coming from cylinder #8, which was the same lifter that was destroyed with the first failure. I will likely switch back to Redline 5W-30 and hope the noise will lesson. I wish I had purchased the non-oiled Johnson Lifters which might have lasted longer than the engine itself. LOL
Joseph, nice to hear from you again, it's unfortunate that it appears that it may be under less than great circumstances however. If indeed the issue has returned, I think we can safely conclude that you've confirmed that it has nothing to do with the MDS, since you no longer have it. What kind of prep/clean-up did you do on the lifter bores that had the damaged lifters in them if you don't mind me asking?
Originally Posted by JosephA
I came across a great article by a former Air Force Metals Tech expert, who now works for a specific custom oil company. This individual analyzed some 120 failed cams and lifters to see if science could determine the cause of failure. His studies indicated the lifters to be the problem, combined with insufficient lubrication. The low-weighted engine oils used by Chrysler do not apply enough film between the rollers and the cam-lobes, which leads to rollers rotating at high RPM speeds. This in turn leads to roller needle bearing failure and/or complete seizure of the roller. Next is time and pressure, after which the roller will have wiped out the cam-lobe leaving excessive debris throughout the engine. His solution was to use a high molly and zink oil with a weight of about 7.5w-30.
I believe you may be talking about the article mentioned here:
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/5452840/1
My takeaway:
Originally Posted by OVERKILL
The letter is an interesting read, the guy hawing a made-up grade (7.5W-40) with a billion ppm of ZDDP? Not so much.
The conclusion that the lubricant is inadequate doesn't make sense, given that as he noted, the valve spring pressure isn't overly high and it isn't a solid roller racing engine. Guys have experienced the issue even on engines run on much heavier additized oil, like M1 0w-40 for example.
I questioned, in one of the other extensive threads on this topic, whether the spring pressure was actually becoming inadequate once the engines got some miles on them, allowing valve float, damaging the rollers, causing them to spall the lobes and eventually lock up.
Roller motors are not supposed to have lofty oil AW requirements, that was one of the reasons they were introduced.
Per the analysis, something is causing the rollers to skid, spall, and eventually lock up and it isn't a lack of lubrication. It could be valve float, defective needle bearings in the rollers or insufficient lifter alignment control, allowing the rollers to scrub due to the body rotating. In any instance, a production street engine with a pretty mild cam shouldn't require Top Fuel levels of AW additives just to keep a cam in it. Given that most of the failures are 2015 and earlier and the lifter part #'s changing multiple times at this point, I expect FCA has/had a pretty good handle on the cause, as did/does GM, who experienced a nary identical issue with their AFM engines.
Originally Posted by JosephA
I do not feel like tearing back into the Hemi engine. So I've decided to dump the stupid thing and buy a better truck..probably a Toyota Tundra since most of the folks I know personally have had well over 300,000 miles on theirs and still runs like new. I also have a 2003 Chevy Tahoe with currently 329,000 miles and the engine still runs and pulls great. However, the transmission did give out and I ended up having to replace the 4L60e transmission.
In your shoes, I'd be soured and looking to replace with something else as well.
Originally Posted by JosephA
Another note by the Metals Tech was his discussion was a Chrysler engineer who stated in a letter that they intentionally designed Dodge/Chrysler engines to fail at certain intervals in order to help maintain employment for Chrysler service departments, or else force the owner to buy a newer vehicle. His words were, "we cannot build a vehicle that will last 15 years or more; doing so would reduce sells, and so we deigned the engines to last the term of the financing...." I for one believe this to be true, because all three of my Dodge vehicles (1997, 2002, 2012) have all failed shortly after paying them off full-finance term.
That doesn't make sense though, as there are millions of these vehicles/engines out there that don't experience the issue over their lifetime. Also, the multiple updates to the lifter part #'s certainly indicates that FCA is aware of isolated failures and working with the supplier to try and eliminate the issue.
Originally Posted by JosephA
Summary:
I'm now convinced the problem is mostly related to poor lifter design. If anyone has repaired their Hemi's using Johnson Lifter, please post any updates you might have as to the longevity of life's engine after repair.
JosephA
Yes, that's my position as well, that it is lifter related, just like with the GM AFM engines. Whether it's exclusive to the lifters themselves, or there is a trigger like weak valve springs and valve float? Would be interesting to know.
