Originally Posted by JosephA
You are correct.
I know, I've been clear on how the system operates from the start.
Originally Posted by JosephA
But is the oil pressure maintained throughout the deactivation operation?
The oil pressure, at the orifice, is NECESSARY to keep the pin unlocked. So it is maintained until the solenoid closes, which in turn shuts off the MDS.
Originally Posted by JosephA
Or is the oil pressure removed once the pin is unlocked? Get my point? Oil pressure is needed to keep the system unlocked.
I've been clear about that the entire time.
Originally Posted by JosephA
Now I might be incorrect about the oil pressure being used to the last possible second just prior to MDS deactivation; this is possibly to help ensure the lifter reaches maximum expansion. And as soon as the lock pin is just about to lock, the solenoid is deactivated and oil flow to the lifter through the solenoid is blocked, leading to a locked lifter.
And this is where you still don't get it. How is the pin about to lock if the system is still pressurized? It isn't! You've got it backwards. It's the solenoid cutting off the pressure to the orifices that enables the pin to slide back into place, disabling the MDS. Oil pressure turns on, and keeps on, the MDS. Once that pressure is removed, the pin slides back into place on the next cycle, disabling MDS.
Originally Posted by JosephA
Now then, if the oil from the solenoid is cutoff during full engine operation (all 8 cylinders), this would mean that the lifters are receiving lubrication normally by another means; the same means the non-MDS lifters receive oil. And this oil must lubricate both the outside of the lifter (body, rollers, etc.), and likewise as a standard lifter, travel through the inside of the lifter to form a path to the push rods, which in turn lubricates rockers and valve springs, etc. The point is, the lifter must maintain lubrication. And what happens when the lubrication is compromised by a opened hole on the lifter where the lockpin would ordinarily be closed? It's going to leak into the lifter itself. Now using physics 101, would this not equate to a drop in volume flow, and hence a reduction in oil flow velocity?
For what must be the 5th time now, where is the oil going to leak to? You keep envisioning the part of the lifter that the solenoid feeds as a black hole, where oil disappears. It's a small hole in the side of the lifter body with a pin, in a cylinder, which it slides in, that, once under pressure, results in that pin sliding backwards a tiny amount to unlock. If the internal mechanism rotates out of alignment with the hole, it doesn't matter, as the small relief in the body that the pin engages is circumferential and when that relief is under pressure, the pin will be displaced.There is no additional path for the oil to follow. Some may squeeze between the body and the bore, but that amount would be quite small.
I'm going to try and explain this with a diagram:
1. This is the standard feed hole present on all 16 lifters that ties into the lifter feed galleries. These are always under pressure providing oil through the body of the lifter, to the roller, and through the pushrod.
2. This is the relief for the MDS pin. It runs around the entire inside of the body, so even if the pin is not aligned with the hole, this is under pressure when the solenoid is live
3. These are the oil paths fed by #1
4. This is the solid block that holds the MDS pin, spring, and the chamber within which this slides. This is essentially the "lifter inside a lifter" that slides up and down when the pin is unlocked.
5. These are the plastic guides we discussed earlier that keep the lifters in-line with the camshaft
Originally Posted by JosephA
Put it to you like this. Oil pressure can be used to indicate the age of an engine. As bearings and parts where down, oil pressure will drop due to less resistance between the journals, bearings, lifters, cylinder walls, etc.
Typically, journals, which are hard, don't wear. It's the bearings that wear, opening up the clearance, resulting in more side-leaking, which in turn lowers oil pressure. Cylinder walls aren't pressure-lubricated, they are lubed with a spray that comes from between the rod and crank. A worn bore will have zero impact on oil pressure.
Originally Posted by JosephA
In the case of the Hemi lifters, if the lock pin is stuck open, then that is the same as a worn bearing; oil travel to that specific part of the system will be reduced in speed, while increased in volume. And a drop in oil pressure/volume to any part of the engine will equate to losses else wear as lower RPM's.
No, it's nothing like that at all. If the pin is stuck open, that lifter simply stays in MDS mode. However, the pin can't be stuck and MDS be on, as the MDS activation depends on the pin being displaced, and thus pressure being provided to the MDS orifice on the lifter body. If the pin sticks, it sticks on MDS
disengagement, that is, when the solenoid CUTS OFF, the oil pressure to the lifter, but the pin does not return to the locked position, leaving that lifter in MDS operation.
Originally Posted by JosephA
Now unless you want to explain how the MDS lifters are lubricated both during locked and unlocked operation, I fail to see how you are not grasping or understanding what I'm trying to explain.
You first need to get a handle on how these things function. I've already explained how everything is lubricated, it's your turn to digest that information.
Originally Posted by JosephA
I will admit my error with MDS operation with regards to the lower half and the upper half of the lifter. I initially assumed the lower end of the lifter is what bobs up and down while the middle half remains stationary. I was wrong. I now understand that the lifter itself remains stationary (through the plastic keepers which might be the culprit causing some slight rotation), and the internals from the top down to the bottom inside the lifter collapse in on itself and the push rod is basically "having sex" figuratively speaking. LOL
I still don't think you follow this part.
The lifter body is a solid piece, just like a conventional lifter, that, when the engine is rotating, follows the profile of the camshaft. This is the case whether MDS is engaged or not. The entire body moves up and down, kept in alignment by the plastic guide at the top, just like the non-MDS lifters. When the solenoids receive power and pressurize the MDS orifices, the lock pins are displaced and the solid assembly that is inside the lifter body; essentially the "lifter inside the lifter", becomes detached from the main body, remaining stationary while the spring that is below it keeps sufficient pressure on it to keep the pushrod in location and allow for conventional oiling to continue through it.
Originally Posted by JosephA
So then, back to the point. If the MDS oil solenoid only "spurts" oil just long enough to unlock the pin, then the lifter must remain unlocked by some other means. However, this is not the case. Oil pressure from the MDS solenoid must remain opened during the entire cylinder-deactivation operation in order to keep the MDS lifters from locking back into place. And THIS ladies and gentlemen is what I've been trying to explain to you all and this is what's causing lubrication problems throughout the rest of the valve train. Once the solenoid opens oil pressure to unlock the lifter, this pressure is maintained throughout the entire time of MDS operation which prevents the lifter from locking back into place; the video I posted shows this. Once the driver demands more power, the solenoid remains open just long enough as the lifter is expanding, and oil pressure is cut to allow the internal lock pin to lock.
1. The above again assumes there is an oil black hole that results in pressure loss. This is not the case as I've explained.
2. Once something happens, whether it is the driver hitting the pedal or encountering a grade to increase load, the solenoid has the power removed from it, which ceases the pressure being applied to the MDS orifices, which then allows the springs behind the lock pins to push the pins back into their grooves, making the lifters single units again. The solenoid does not, in any part of this, "remain open" when MDS is called to be deactivated. It is the cessation of oil pressure caused by the solenoid being deactivated that allows the pin to seat, thus disabling MDS.
Originally Posted by JosephA
If the lock pin does not lock, then oil (normal oil lubrication during extended use) is wasted on those lifters. And THIS is why we do not see lifter/camshaft damage prior to MDS and DOD introduction.
Joe
If the lock pin does not lock, that lifter remains in MDS operation, which would be noticeable. Everything else would operate normally. And I've provided numerous examples that show lifter failure happens on non-MDS engines, you claiming that it doesn't at this juncture is utterly ridiculous.