A lot of people dont seem to understand how the Oiling system works So I will try to explain it with drawings and tests that I did years ago. We tested 100 VW stock dual relief motors.
All motors were diaasembled, cleaned and had cranks reground and new bearings installed to spec.
The same oil pump was used in each motor.
The same oil cooler was used on each motor.
All the cases were line bored, full flowed and a flow meter was installed in the loop from the pump to the case.
This first drawing is the oil flow and pressures when cold with a oil temperature at 80 F.
There was a wide variety of pressures and flows recorded and I will explain the findings when I come to them.
I will add new drawings as I transfer the data to the drawings.
This is the flows and pressures at 120 F oil trmperature. At this point oil is just starting to flow thru the oil cooler.
Here you see the motors are at operating temps, 180F Everything should be fine but the relief valve is still open. We kept running the motors and most of them reached 225 before we shut them off and most of the relief valves never closed.the relief valves never closed. The motors never went over 225 either. All the excess oil is still running out the control valve. It is open 100%. I will explain this in another drawing.
Here are the motors at Idle. Notice that the relief valve has closed and the control valve is closed. All the oil is now flowing thru the oil cooler.
This is again up to 3000 RPM after Idle at 190F
Notice now the relief valve is closed and the control valve is open.
All the oil is flowing thru the cooler and a lot of oil is flowing out the control valve. Interesting aspect of the relief valve and is that it opens at a much higher pressure than it closes at. Ill explain that in another drawing.
Next drawing. Here is where we started having problems.
Notice the high pressures. There were 6 motors that reached that pressure due to different reasons. We lost 6 oil coolers at this point. Had to find the problems and retest all 6. Today this would show up as blown oil filters too.
Notice the increase in oil volumn. . This extra oil has nowhere to go because the oil relief hole is too small. that is why the pressure increases so much.
Here is 120F notice how no oil flow thru the cooler. Pressures are equal everywhere.
Here is 190F The oil is flowing thru the cooler but the relief valve does not close due to the high pressure.
Here the motor goes back to Idle and still the pressure is too high to close the valve.
Here is a section of the oil control valve Notice the opening and closing pressures of the piston.
This is the plug that needs to be removed and drilled.
Oil Flow restrictor. I will update this later.