For……… too long my oil circuit has been draining after a prolonged stop. Balance, it takes at least 15 seconds to restart to regain oil pressure (turn off the sight glass).
I changed the pump, the pump casing, the strainer and even the engine block. Without result!!!
So to avoid waiting for the worst, I decided to install a battery (oil pressure accumulator).
The accumulator: It consists of a cylinder with a piston. On one side of the piston, air under pressure, on the other the oil reserve.
The solenoid valve and its pressure sensor.
Pitting on the oil circuit, after refrigerant (accumulate cold oil). After the oil filter to avoid impurities that could alter the surface of the cylinder and piston seal.
Advantage: the oil filter serves as a valve, all the oil is directed to the engine block.
Note: In all cases, the oil pump is gear driven, even if its tightness is not perfect, it acts as a valve.
As my oil filter is not offset, it is directly on the engine block.
Principle of operation:
An accumulator and a manual valve. This arrangement is mainly used for pre-greasing when starting the engine. During operation, the valve is open, the pressure in the accumulator is that of the oil circuit. Before stopping the motor, the manual valve is closed, the pressure in the accumulator is constant (that at the time the valve is closed). It can be interesting to carry out this operation in accelerated mode to have a maximum pressure. Before restarting the engine, the manual valve is opened, the pressure in the accumulator drains the oil into the circuit and pre-greases it.
Installation with electrical control:
The manual valve is replaced by remote solenoid kit, the principle of operation is identical.
The solenoid valve can be ordered: by a switch on the dashboard, or directly powered by the +12V ApC. It will close when the ignition is switched off while the oil pressure is still normal in the circuit and will open as soon as the ignition is switched on again (before operating the starter) (the pressure in the accumulator will force the oil into the lubrication circuit.
Mounting with solenoid valve and pressure sensor:
As in the previous case the system is powered by the +12V ApC.
The pressure sensor 20-25 psi (1.4-1.7 bar) or 35-40 psi (2.4-2.7 bar) or 55-60 psi (3.8-4.1 bar) is connected in series with the valve, it measures the pressure in the lubrication circuit.
When the pressure exceeds the high threshold the contact is open, the valve is closed. When the pressure in the circuit drops below the low threshold, the contact is closed, the valve is opened, the accumulator supplies the lubrication circuit.
Choice of pressure sensor: it depends on the engine characteristics. During normal operation, the solenoid valve must remain closed (keep the pressure reserve in the accumulator). Therefore, the low threshold must be above the minimum pressure in the circuit during normal operation (usually at idle). This condition could make us choose 55-60 psi, but in this case, the valve would not close before the high threshold, and therefore the reserve would not be replenished.
Conclusion: Choose the value just above the fuel pressure at idle.
Advantages of the pilot operated solenoid valve: In the event of “lift-off” (mainly on the circuit), the lubrication pump defuses, the oil pressure drops sharply. The oil pressure is maintained by the discharge of the accumulator for 20 to 60s (depending on the size of the accumulator and the type of engine – oil consumption).
Note: For pre-greasing before starting, same operation as above.