Back when I pulled the engine I removed the oil pressure regulator
to clean it up a bit and to see how it worked.
Fig. 1 shows where the
regulator attaches to the block. Remove the two 8mm x 1.25 bolts that hold
it to the block. Note there is a gasket between it and the block. Disconnect
the oil line from the end of the regulator.
2-3 show the removed unit. There is not a lot to
it but lets take it apart, clean it up and see what's inside.
Disassembling the regulator
All apart, and Cleaned
I clamped the regulator in a vice and used an adjustable
wrench to loosen the lock nut. See Fig. 4. Once
the nut is
loose then the adjuster can be backed out all the way. Next will be a spring
and then the regulating piston. See Fig. 5. I
put the housing in the parts washer, de-rusted it, then sand blasted it. The
piston, spring and adjuster/nut were hand cleaned. While cleaning the adjuster
I noticed the oil seal was cracked, I'm still looking for one... (Update: found
FSM Oiling diagram
Pump to Regulator Oil
Oil Gallery Flow
Regulator Oil Flow
So how does the F engine oil pressure regulator work? Well first
refer to Figs. 5-8 for how the oil
flows through an F engine. The oil is sucked up through the oil
strainer, into the pump, pumped through the hard line and into the lower engine
oil gallery. This gallery runs the entire length of the block as can be seen
in Fig. 8. The oil pressure sending unit is screwed
in to the gallery to measure oil pressure.
main crank bearings, splits again and goes to the cam bearings then
the head where it lubes the rocker arms.
Now what happens is this: When the engine FIRST cranks over
there is NO oil pressure. Refer to Fig. 9.
The spring in the regulator keeps the piston seated so that the line to the
oil filter is CLOSED. This forces ALL the oil to the main bearings in the
engine for startup. Once the oil pressure reaches 44-50 PSI (or whatever
the regulator has been adjusted for) the spring is compressed allowing the
piston to move off the seat gradually opening the passage to the oil filter
as the pressure rises to its maximum. This
some of the oil from the oil gallery to the oil filter where it's filtered
and returned to the oil pan via the hose that screws into the block as shown
6 and 8. One consequence of this type of system is not all of the
oil is filtered before it reaches the bearings. So change your oil often!
ANY debris left in the system can find its way to the bearings!