Relief or pressure regulating valve on 218 "motor

[Sebastian Soutiño]

Hi all! This time to ask you about this valve, which in my opinion would be the culprit for the loss of oil pressure in my Ply 47 engine. The first question that occurs to me is how do they replace this when they rebuild an engine? Is there a spare? In my case not only is the piston damaged but also the shirt where it is housed.
Thank you for what you can contribute.

[dpollo]

pressure relief valves rarely cause low oil pressure.  During an overhaul the valve is removed , cleaned and replaced.

 

Low oil pressure is most often a result of worn bearings, worn oil pump, or badly diluted oil.

[Sniper]

Don;t forget the cam bearings, IIRC, the cam bearings get oiled before the mains in our flatties and a lot of times a rebuilder doesn't replace them.

[greg g]

Usually the valve sticks open causing high oil pressure.  Factory calls for 50psi for maximum operating pressure.  I believe you should clean the area where the valve seats and buy a new piston and spring and see what happens.  You can block the passage with a small screw, then fill the area up with white vinegar (vinegar if a 5% acid solution) it will attack the rust in there, may take a few days and a few refillings but it should get all the corrosion out so you can polish it with some fine Emory cloth.

[Sebastian Soutiño]

 

What would be the maximum and minimum pressure range recommended for an engine in good condition?

At 700 rpm the pressure drops to almost the minimum