996scott

so I just made the mistake of taking out the pressure relief valve (i think) instead of the drain valve while changing the oil. I was thought I could just get it back together and then I found this little part (the one I am pointing to in the picture) and I am not sure where it goes. help please. Thanks guys..

Cupcar

It is a spacer that goes over the gold tube you show entering the spring and under the spring. It nests on top of the flange on the gold tube. Then the whole assembly goes spacer side down into the threaded plug.

996scott

Cupcar, thanks for the quick reply. so this picture is how I imagine it going back into the car. When I was finishing taking out the oil filer the "cap" fell out of the hole. So is this right?

Cupcar

No, flip the spring over so the gold tubed end is in the threaded plug and the spring alone goes into the relief piston.

IXLR8

Here you go....

996scott

got it guys. thanks a ton!!

badabing

I did the exact same thing a few oil changes ago. Also got instantaneous assistance from the good folks here.

Got to love this place.

SchnellAuto

generally , that ring or spacer set the pressure...the old time mechanics sometimes shim the bottom of the with washers to increase oil pressure..

lemon

Cupcar

That is exactly what Porsche did here, the 3.2 engines have the same spring and spool but no spacer.

It really doesn't matter where the ring goes, over the tube onto the flange or under the flange of the tube, Porsche has illustrations that show it in either place.

996scott

Thanks again guys, it is amazing how knowledgable everyone is and how willing everyone is to help those of us that are far from mechanically inclined but like to try a few things every now and then. So how exactly does the valve work and what does it do?

IXLR8

Its a "pressure relief valve" and the design (piston diameter and spring rate) sets the pressure that it opens at. In this case 5.3 bar or 78 psi. (A)

There is "safety valve" that opens at 9 bar or 132 psi. (B)

Notice how they have the orientation of items 4 and 5 different in this service manual pic than the one previously posted.

SchnellAuto

i had a cow once on my seventy. took it to my old mechanic and he told me my 70 was a euro...and the measurement were in bars..not in like the american version...

duh.. felt like homer simpson


Lemon

Cupcar

Oil pressure is a function of oil flow and oil gallery resistance.

The oil gallery resistance stays the same.

As engine RPM increase, the positive displacement oil pump increases in speed along with RPM and thus increases oil flow delivery to the oil galleries.

When flow is enough to raise pressure to push the "pressure relief" valve piston off the orifice it plugs, flow is diverted back to the intake side of the pump in late engines (early engines forgot year, pre '72?, divert to sump), thus decreasing flow and thereby pressure is relatively constant over a range of RPM as the piston is pushed further off the orifice as flow increses.

The "safety valve" is a hail mary save if the engine is over revved when cold to prevent too much oil pressure and diverts oil directly back to the engine sump.

accted

nine9six

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