944 83 mod oil pressure

I have a problem with oil in the radiator, no water in the oil. I have removed the cooler & replaced the gaskets & checked for leaks. All appears in good order. My concern is with the oil pressure relief valve there are no 0 rings or seals , yet the book shows an 0 ring seal. The pressure always appears high on the gauge showing the needle at the stop when ever over 300rpm even when motor is hot. Has anyone a detailed drawing showing the early 944 oil pressure relief valve in detail & a description of operation. Would the ommision of the seals allow oil pressure past the valve & excessive pressure in the housing.causing the leak to coolant? Help would be much appreciated johnsundri@netscape .net