F150Torqued

I think it IS the base - residual pressure remaining in the oil galley of the cylinder head after cam bearings / lash adjusters / VCT solenoids weaps a little out. I've taken a phaser apart and there are passageways milled in one of the chambers behind the locking pin. Oil can push it up against the spring. But there is the unknown factor though. I have NO idea how much oil pressure is intended to be in the heads / phasers after passing from the engine Block Oil Galleys - through the restrictor into the heads. But it is likely NOT the 25 Lbs we would read on our gauge. Something less.


I think the little milling is there to allow enough 'movement' at low pressures for the locking pin to 'capture' the back plate/camshaft and lock them into place - at AROUND Zero Degrees.


And YES, that would be impacted by oil viscosity as well as base pressure. Is this why 5w20 is recommended? The chambers have no oil scraper like piston rings or oil seals. By design the Front and Back plates are not sealed. I think it is intended to be a source of seepage oil for oiling the chains.


And YES, I believe wear / slop in the locking pin and overall degradation of oil pressures in the head / phasers / tensioners are the source of the noise. ie: the "Diesel sound" at idle which immediately goes away on the slightest acceleration.