[boyt911sc]

Originally Posted by KTL

The pressure in the scavenge circuit is very high when cold. But the key is that this section of the oil path with the trombone loop is blocked on the return side when cold. It's just a "stack" of oil that is waiting to move until the thermostat opens. So there is no flow and thus no pressure. The point I'm getting at, is this part of the oil system isn't under pressure until the oil at the thermostat is just above 180F

But for reference, here's an example of the pressure created by the pump elsewhere when cold. If you don't run a thermostat before the oil cooler, you risk damage to the cooler and other things when the oil is cold and thick

http://forums.pelicanparts.com/911-engine-rebuilding-forum/632726-911-3-0l-sc-oil-cooler-system.html#post6308846

Kevin,

Why would the oil pump scavenger side be having very high pressure when cold? From the diagram, oil from the sump area is sucked by the oil pump and directed to the auxiliary thermostat. Where is the restriction point to produce this very high oil pressure? The cold oil by-passes the auxiliary thermostat and goes directly to oil tank. I have not dissected an oil tank and have no idea how the internal plumbing works. Thanks.

Tony