Filter housing spring loaded pressure release question Series II

While at a restoration shop yesterday they fired up a newly rebuilt engine on test stand. Oil pressure was at 70 lbs. I know on my engine anything over 60 lbs will pop the pressure valve and pressure will drop. I am confused as to there being one or two
spring loaded valves in filter housing? Have a sealed unit in housing is there a 2nd
one where by pass hose goes from housing to sump?


My 1970 has one pressure valve

Its the one on the right side of the photo, the left opening is where the oil is pumped in from the oil pump. If the filter plugs or the pressure get to high the valve would open up dumping oil past the valve and then it drains down the hose to the sump. There is not another valve in the bypass hose.


There are two relief valves in your oil filter housing. They serve different purposes. The pressure relief valve looks like this on the Series 2:

It screws into the base of the housing alongside (and aft of) the spigot to which the bypass hose to the sump is attached. When oil pressure exceeds around 65 psi the valve opens, and oil is diverted back to the sump via the external hose.

The second relief valve is located inside the filter housing and consists of a valve which is normally held closed by a bee-hive spring.

Close up it looks like this:

It’s purpose is to handle the case where the filter element is clogged, and preventing adequate flow of oil. If the filter is clogged it diverts unfiltered oil directly to the oil feed gallery. In normal operation it should be closed at all times.

Hope this helps.

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Thanks guys, no longer confused.
I have had that valve on the bench and tested it with air pressure and mine opens at 60 psi. Have found that if I take car out on highway before it is fully warmed up it will pop that valve. Can see sudden drop of pressure on mechanical oil pressure gauge for 1/2 sec.
and then will return to normal if rpm is reduced.
Do not believe a replacement valve is available and no way to adjust?



SNG Barratt shows the (Part #11672) as a “Special Order Only” item. XKs says they are NLA. As you say, I don’t believe they are adjustable.