Oil Return: Oil Filter

[sastanley]

HalcyonS, It isn't quite that simple, but I cannot answer it for you completely. Some areas of the crankcase like the valves, it just splashes around, and apparently having the cover off does not affect oil pressure, and I guess the unpressurized oil trickles down there.

Someone else that has torn one apart in detail will have to explain further. I think that maybe the crankcase itself is pressurized, so that oil gets pressure fed into the cylinder walls and crankshaft/camshaft, etc. The Indigo system gets its feed from the OEM oil pressure sender 1/8" NPT hole and then is fed back in via the 3/4" hole just under the fuel pump. Older versions had a pickup tube (which in theory are great for pulling oil out for oil changes, but the newer ones do not...it just dumps in based on the newer diagrams.) I have the older style, but I still pull my 3-ish quarts out of the dip stick hole, because I am too lazy to engineer anything better.

So, if I understand correctly, the pressure valve in the older Indigo system up near the filter is likely a relief valve, and it keeps the crankcase pressurized and any extra/bleed off it lets into the oil filter, which in turn dumps into the sump. The Indigo kit comes with a couple of parts to bottom out (maximize) the pressure at the OEM oil pressure regulating valve in the engine block.

[hanleyclifford]

On the Right Track

There is a flow diagram on page 5-3 of the Moyer marine Service and Overhaul Manual. Notice that the relief valve is located in the block very near the pump. If you go to an externally relieved system (like the Indigo) the procedure is to "two block" the stock relief valve and relieve some place else. Bear in mind that because the oil system is dynamic pressures are not constant throughout.

[jpian0923]

Oil circulation and description

http://www.moyermarine.com/forums/showthread.php?t=5579

[HalcyonS]

Thanks Jim (and Jerry), helpful.