4.7 updated rockers with smaller orafice question
#21
So the hole we were discussing is in the rocker arm where it contacts the lifter. As I understand it, the oil enters thru that little hole in the side (see lifter on left), then eventually exits thru the top. The lifter sits vertically (well sideways, actually), so I don't think the rocker has anything to do with the leak down.
These lifters for the 4.7L are the same brand and part number, however the one on the left is considered the improved version. Notice the smaller hole at the top. I guess the lifter on the left should keep a better pressure than the right.
These lifters for the 4.7L are the same brand and part number, however the one on the left is considered the improved version. Notice the smaller hole at the top. I guess the lifter on the left should keep a better pressure than the right.
On bleeddown, when the engine shuts down the springs should collapse the lifters. Once they are collapsed, the oil's surface tension should be keeping oil from gravity draining out of the lifter for at least a couple of days. If the hole in the top is too large, then surface tension won't be enough to keep air from forcing its way in.
The noisy lifter isn't going to be due to the smaller top hole,, because the small side hole is the pessure restriction. My thinking is that there might be an issue with the lifter. It's possible for a new lifter to be bad out of the box.