Originally Posted By: robd
What I also noticed was that the bypass valve took an extreme amount of force just to open off its seat compared to other brands of filters used on this vehicle. I know this is very unscientific but the amount of force to open was almost ridiculous. I think Purolator may have something bad going on with their bypass valves causing deformation of the media and tears on cold starts or higher flow. This particular one has the bypass valve with the circular leaf spring.
The whole spiral leaf spring bypass valve design has been discussed a few times. You're not the first guy to think it's too stiff, but if you actually measured the force to make it crack open, and then measure the effective area that the delta-p acts on, you will calculate that it cracks open in the PSI range that Purolator says it should.
That bypass valve design is also used on many Purolator filters that don't show any signs of media tears. I've said it a dozen times in these threads, the media tears because the pleats on both sides of the seam are spaced out too wide, and potted into the end caps with too much of a "V" shape. The force produced by the oil flowing into the sides of those pleats causes too much side force on the pleat, and the media ends up tearing/failing at ends of the pleats where they are glued into the end cap.
What I also noticed was that the bypass valve took an extreme amount of force just to open off its seat compared to other brands of filters used on this vehicle. I know this is very unscientific but the amount of force to open was almost ridiculous. I think Purolator may have something bad going on with their bypass valves causing deformation of the media and tears on cold starts or higher flow. This particular one has the bypass valve with the circular leaf spring.
The whole spiral leaf spring bypass valve design has been discussed a few times. You're not the first guy to think it's too stiff, but if you actually measured the force to make it crack open, and then measure the effective area that the delta-p acts on, you will calculate that it cracks open in the PSI range that Purolator says it should.
That bypass valve design is also used on many Purolator filters that don't show any signs of media tears. I've said it a dozen times in these threads, the media tears because the pleats on both sides of the seam are spaced out too wide, and potted into the end caps with too much of a "V" shape. The force produced by the oil flowing into the sides of those pleats causes too much side force on the pleat, and the media ends up tearing/failing at ends of the pleats where they are glued into the end cap.
