Originally Posted By: CLOVER
Quote:
BTW - he made it sound like he thinks the oil flow will be cut back if the filter goes into bypass mode. That is only true IF the oil pump has also hit pressure relief. If the oil pump is not in pressure relief, then 100% of the oil volume coming out of the pump is still going through the filter & engine ... even if the filter is bypassing some of that oil.
Yes, It is a positive displacement pump, so the flow is not affected by the filter pre-relief,
and, post-relief, the pressure is high enough (in this case 100psi) that there
will always be enough pressure to the motor...100psi relief minus 35psi bypass = 75psi.
But if the filter is badly compromised the motor sees unfiltered oil after relief
and at any other time pre-relief.
That was my comment about the positive displacement oil pump and oil flow volume.
If the oil pump pressure relieve is set to 100 psi, and the oil filter bypass valve is set to 35 psi, then 100-35=65 psi. So theoretically, if you only saw 65 psi on your oil pressure gauge - which I assume is located after the oil filter - then that would mean the filter delta-p was about at 35 psi and going into bypass.
Keep in mind, this would have to occur at really high RPM with somewhat cold oil in order to make your oil pump hit the 100 psi relief pressure. If you are driving around mellow at low RPM, the oil pump isn't going to approach 100 psi because the volume coming out of the pump at low engine speeds is much less, and therefore the resulting pressure is also less.
If the oil filter was only producing say 10 PSID when the pump was producing 100 psi (pressure relief at near redline RPM), then you should see ~90 psi on you oil pressure gauge.
If the filter was very clogged up, it could be producing 35+ psi of delta-p, which would make the bypass valve open even at lower engine RPM when the oil pump is not in pressure relief. In that case, you could not tell from looking at your oil pressure gauge what's going on because 100% of the oil coming from the pump is still going to the engine, and the oil pressure will therefore read the same. The pump has to be in pressure relief in order to determine the actual filter pressure loss (delta-p) when monitoring only one oil pressure gauge that's located after the oil filter. The only other way to determine the actual delta-p across the oil filter when the pump is not in pressure relief is to use a pressure gauge before and after the filter to see the delta-p across the oil filter.
Originally Posted By: CLOVER
I said "compromised", What you can see in the photos and drawings is the pleats
jamming together between the axial supports and deforming over the radial supports.
this must significantly restrict the capacity of this filter.
I am doing some testing:
This car has Approx 100psi relief and 35psi filter bypass.
New oil and filter.
Cold idle: 100psi supply.(relief open)
Warm idle: 45psi supply
When warm the press relief opens at 4000rpm.
Pressure across filter 2-3 psi.max.
Not sure how you're coming up with "pressure across filter 2-3 psi max". Based on the large impressions on the media that presses against the center tube cage, there's been way higher than 2-3 psi across that oil filter.
Are those pressure numbers above what you actually see on your pressure gauge? So you are saying the pressure goes up to near 100 psi (like 85~90 psi) at 4,000 RPM when the oil if fully hot?