Bob,
I will try to explain how the oil from the engine flows through the auxiliary oil thermostat. Imagine the four (4) oil line connections for the thermostat:
A...........from scavenger oil pump inside motor.
B...........oil return line to the oil tank.
C...........oil line to the auxiliary oil cooler.
D...........oil line from the auxiliary oil cooler.
- Oil pick up by the oil scavenger pump is delivered directly to the aux. oil thermostat (A). The initial flow of cold oil goes to (B) and (C).
- Cold oil flows straight thru thermostat (C) to fill the oil line and cooler and to the oil tank (B). At this stage all the oil from the engine goes to the tank after filling the oil lines and cooler.
- At temperature below 185°F, the valve @ B is fully opened and valve @ D is fully closed.
- This oil circulation goes in cycle until the engine oil gets warmer and warmer.
- At around 185°F, the slide valve inside the thermostat will start to move. The opening/closing of the valves orifices is the same to maintain the flow of oil.
For example:
Valve B (100% open)/ Valve D (100% close or 0% open)
Valve B (80% open)/ Valve D (20% open)
Valve B (50% open)/ Valve D (50% open)
Valve B (fully closed)/ Valve D (fully opened)
Etc.
This is how the auxiliary thermostat operates in conjunction with the oil cooler. Below are some of the auxiliary thermostats I used for the tests.
Tony