Should an oil cooler cause oil pressure to drop?
 

For the past few weeks, I've been studying oil coolers and sandwich plates.

A thermostatic sandwich plate is a "2 channel" system. When the engine is cold the oil flows through channel 1, bypassing the cooler. At 180*F or 82C* (whichever comes first) channel 2 opens to the cooler. Channel 1 is still open.

So, the amount of flow through the cooler is irrelevant. Even if the cooler only flowed 1/2 pint per fortnight, channel 1 is still open so oil pressure shouldn't drop.

What am I missing?

Channel 1 shouldn't really be open at temp. Pressure drop is caused by obstruction through the sandwich and heat exchanger. Unless I'm mistaken somehow

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Pressure drop is real. Accelerating mass around sharp corners, turbulent flow, blah blah... all is work resulting in head loss.

Mocal http://www.mocal.co.uk/products-oilcoolers.html gives the pressure drop thru their various cores. But the engine will not feel this pressure drop most of the time since the oil pump is a positive displacement pump (will pump a fixed vol of oil vs engine rpm, ie higher rpm = more flow). So even if there is huge restriction at the oil cooler, it will try to maintain the flow and we end up with higher pressure after the pump before the oil cooler. Also, the pressure relief at the oil gallery is triggered for a large proportion of the rev range.

Unless the pump starts cavitating. A theory that needs to be tested.

My question mainly revolves around what is happening at the sandwich plate. I see where the oil flow is open to the cooler at 180* but I don't see where that cuts off flow to "channel 1".

My choice of oil cooler was dictated by shortest and greatest number of tubes. The Sebrab Series 1, 34 row seemed to be the best compromise.

A sandwich plate with a Vernatherm works different than you described. When cold the Vernatherm is short allowing oil to bypass the cooler. As the oil get hot it expands and shuts off the bypass and forcing all the oil to go through the cooler. Or some ratio between the two.

You guys are correct. I found this video. For me, it helped clarify what the dang thing does.

https://www.youtube.com/watch?v=l6Z2q-ttyOA