Ok, If you want the real story on why the lifters fail, keep reading.....
Everyone knows how MDS works by now. The problem also occurs on non-MDS engines. The cause has to do with the way the engine gets oiled. In most engines oil gets sucked into the pump, travels to the filter and then to the crank and cam journals. The lifters then get fill, oil continues up the push rod to the rockers, and runs back down into the pan. If we did that to the Hemi's, we would starve the MDS cylinders when activated. For this reason the Hemi's are oiled backwards. What that means is the oils goes through the pump. then filter, and crank journals. Instead of pumping up the lifters, oil goes to the rocker arm shafts to the rocker arms, down the push rods, and finally the lifters. The lifters are the last thing to recieve oil! In order to meet fuel economy standards the good old US of A required, MDS was the only way these engines are able to be produced! The only way to make MDS work, is to modify the lubrication circuit. I can't believe how many different theories are floating around as to why the lifters have issues. During my time working for Chrysler I had the opportunity to speak with one of the engineers and designers of the engine. So there you have it, the real story about Hemi's lifter issues. One other tid-bit for you before I leave you. Ever wonder why there are 16 spark plugs? It was actually a mis calculation. When work began on developing the 5.7 Hemi, it was believed that 16 plugs were needed to make it through California's smog check program. Only when the final design was completed did they realize that it was not necessary. They were not going to re-design the heads, and re-tool the assembly lines to correct it. Cheaper to throw in 8 more spark plugs! Cheer's!
