The AERA Technical Committee offers the following information regarding sudden loss of oil pressure on 1997-2005 Chrysler 2.7L VIN R, U and V engines. This loss of engine oil pressure has usually occurred shortly after replacement of the engine oil pump.
It has been reported that certain replacement oil pumps on the above-mentioned engine use an expansion plug to secure the oil pressure relief valve within the pump cover. If the plug dislodges, a loss of oil pressure will result, as oil will route back into the oil pan.
The original design pump incorporates a screw-in plug to secure the pressure relief valve as shown in Figure 1. No reports have been received of that style plug coming loose during regular engine operation.
This oil pump also relies on correct crankshaft location when installing to prevent engine damage. Refer to Figure 2 and observe the location marks while the #1 cylinder piston is 60° after top dead center (ATDC). 
