- Jun 1, 2003
shimming it will ONLY bring the cold pressure back up. the OPRV does NOT make oil pressure it just controls the maximum it is allowed to make.
I suggested shimming (reply #11) only to ensure you were not getting leakage at the pump seal.
If there is leakage, a shim should show an increase in oil pressure when hot.
With zero leakage there will be no increase in oil pressure when hot.
With cold oil, and zero leakage, the OPRV determines the pressure, which should be approx. 65 psi. Adding a shim with these conditions will have no effect on pressure.
From your description, you have adequate oil pressure when oil temp is 155F. The fact that the pressure drops when you push it hard indicates thinning oil due to higher temperatures. You can add a cooler, but since you say you do not intend to ride that hard, adding a cooler is likely irrelevant
To reiterate, adding a shim will serve to ensure zero leakage. This will require oil pressure and oil temperature checks with AND WITHOUT the extra shim. If the pressure hot increases, leave the shim in, otherwise take it out to avoid too mush squish.
What you say is true ...... but consider the additional .....how do you figure this. if the oil pressure when hot is anything below the relief valve setting than no matter what you do to the OPRV it WILL NOT change the oil pressure. he has found the relief pressure setting when cold and that is when it will have maximum pressure and the valve will open. when hot and the pressure drops below OPRV setting it shows the pump cannot pump enough volume to overcome the leaks. the leaks i am referring to is a stack up of rod bearing clearances, oil pump clearances, seal in the timing cover to crankshaft, leaks around the oprv and the rocker arm shafts.
What you say is true ...... but consider the additional .....
Adding a shim does NOTHING TO CHANGE THE OPRV SETPOINT!
IF adding a shim increases oil pressure when hot, then one can infer that leakage past the conical seal has been decreased. The shim ONLY AFFECTS THE CONICAL SEAL!
Hope this clears it up.
Are we talking about a shim under the conical seal, or under the OPRV spring?adding a shim has everything to do with the set pressure where it opens just like a valve spring shim will change the seat pressure. adding a shim cannot have ANY effect on ANYTHING if it does not reach the set opening pressure of the OPRV and this includes the conical seal on the oil pump to timing cover and that is one more place for it to leak and not reach the set OPRV setting.
Are we talking about a shim under the conical seal, or under the OPRV spring?
My comments relate to a shim behind the conical seal.