Wild one
Senior Member
- Joined
- Jan 17, 2016
- Posts
- 14,559
- Reaction score
- 25,755
- Ram Year
- 14 Sport
- Engine
- 5.7
The hemi has 4 lifter oil galleries,that each feed one set of mds lifters and one set of non-mds lifters.The mds solenoids restrict oil flow to the lifter bores when mds is disengaged,basically starving the lifter bores,which has been known to lead to lifter scuffing.But there's viscosity, and there's flow rate. They are inversely proportional. Higher viscosity does no good if it can't get to the part - which is where machine design comes in.
The galley and part clearances have to be wide enough for the viscosity of oil needed to keep the parts separated by the oil. If the design goofs up one or the other, the parts are underlubricated.
Which I think is the problem here. The lifter body scuffing is indicative of insufficient lubrication of the bore. Again, I'm unclear if the oil galley feeds every lifter bore, or only the MDS lifters.
Anyway, this is why I leave MDS on when dead-heading (no load), to sporadically feed the MDS lifter bores. It's also why I'm careful to balance oil viscosity to be heavy enough to lower wear but light enough to flow sufficiently to small galleys and parts. Plus low flow resistant oil filters.