Originally Posted by ZeeOSix
Originally Posted by Railrust
Originally Posted by ZeeOSix
Originally Posted by Railrust
The PF63e has a bypass pressure of 22psi which is important for the 5.3 engines as they build pressure up evenly through the entire crankshaft before oil pump relief valve regulates pressure (whatever that does, I don't know).
Is this another comment thinking that the filter bypass valve somehow effects the pump's pressure relief valve?
I'm not saying that, not sure that is the case. All they mention is the filter needed a higher pressure to help maintain consistent pressure through the crank, and a less pressure filter would allow contents to flow into the engine.
Link to this info?
Only thing the GM TSB basically says is that they went with a higher filter bypass valve to help prevent filter bypass events on cold start-ups because of where the pump's pressure regulator sensor was located.
With a positive displacement oil pump, the oil flow going to the engine will be the same unless the filter is so restrictive and clogged (highly doubtful) that it would cause the pump to hit pressure relief. Might happen at temps of -20 F or colder during a cold start-up.
But certainly, the filter's bypass valve setting has absolutely nothing to do with how the oil pump or the oil pump's pressure relief valve works.
Building on what ZeeOSix said.
It is my understanding when GM made the variable rate oil pumps, they wanted to ramp the oil pressure up quickly on startup. In other words, get the oil where it needs to be more quickly on startup. To accomplish this, they also used remote sensing for the oil pump's output pressure. In doing so, the design has a time delay between the actual pressure and the sensed pressure. When this happens on startup, there is a pressure spike which would cause the bypass valve to open in the oil filter. To reduce the number of bypass events, then GM began specifying higher bypass valves for their oil filters to be used on engines with variable rate oil pumps.
GM believes they are reducing engine wear by improving oiling at startup and reducing the number of bypass events.
I believe they are likely correct.