Oil cooler adapter bypass valve

Update:
After a few hours on the boat so far this season, I am seeing stable oil pressure.

Looks like the change to a full flow filter did the trick.

Thank you all once again!

 

The bypass pressure relief valves in the filter mounting base and in some filters, guess what happens when the filter is dirty?
Oil flow bypasses the filter, so engine gets unfiltered oil.

So guess what happens when the oil filter is partially dirty and cant flow well, the relief valve opens slightly and you get a mix of dirty and filtered oil running to the bearings.

There is no way to tell if the valve is opening to allow dirty unfiltered oil to the bearings, so change the oil filter on a regular basis. Dirty silt laden silica dust in the oil works like a grinding fluid on bearings wearing them down.

I have 2 types of filters on the car engine and the boat engine which I added myself since I am interested in oil lubrication.

One is the full flow, where oil from pump passes thru filter then onto the bearings.
Other is called bypass, bleed stream filter. This takes a small amount from the pump, passes it thru a restrictor orfice, the oil is filtered at a very low 1 -2 micron level and then the filtered oil is dumped into the pan.

A full flow conventional oil filter is a compromise between particle size and sufficient oil flow to keep the engine alive.
Research has shown that particles under 10 such as the 5 micron level slip right by the conventional full flow filters and that is the size that tends to cause the most wear. So using a bleed stream bypass filter removes the small fine grit that the other one does not.

Of course this is a trade off between longer life for engines vs planned obsolescence for the engine manufacturers, which is why you dont see them on a car engine. You likely will see bleed stream filters on large expensive engines where lifespan and continued operation is more critical. You also see them more on Diesels which tend to form carbon dust into the oil.

The way to do this is have both types working on an engine.