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From The Saab Tech Wiki
==Overview==
The pressure reducing valve (relief valve) controls maximum oil pump pressure. It is located below the balance chain area. The valve piston moves up and down with oil pressure and is easily damaged by metal particles from a worn balance chain or from the balance chain sprockets. If the valve sticks open, oil pressure will be low. If closed, pressure will exceed maximum pressure at high rpm. The oil pressure reducing valve can be inspected along with the timing chain tensioner, valve cover, oil pan and oil pickup screen to assess the condition of the engine.
[[file:900_9-3_Oil_Pressure_Relief_6.gif|thumbnail|none|Fig. 1 - Timing Cover and Oil Pressure Reducing Valve Diagram (engine side)]]
Pictures and other content below were provided by jonnyfgroove on SaabCentral Forums. Thanks also to Anders (Swedecar) for documenting reducing valve scoring and other balance chain issues on SaabNet.
==Access and Inspection==
===Access===
The oil pressure reducing valve is accessible from under the car, after removing the plastic right front air shield. The right wheel, and the plastic shield over the crankshaft pulley can be removed for more room to work if necessary.
[[file:900_9-3_Oil_Pressure_Relief_5.jpg|thumbnail|none|Fig. 2 - Front Air Shield]]
===Removal===
If the piston sticks in the bore, it may have to be removed using a pick or a similar tool. In that case, the pick must be inserted carefully into the hollow piston to avoid scratching the walls of the bore.
[[file:900_9-3_Oil_Pressure_Relief_1.jpg|thumbnail|none|Fig. 3 - Oil Pressure Relief Valve Cap]]
===Components===
The valve consists of a cylindrical piston, a spring, and a cap with a gasket. The spring fits inside the hollow portion of the piston.
[[file:900_9-3_Oil_Pressure_Relief_2.jpg|thumbnail|none|Fig. 4 - Oil Pressure Relief Valve Components]]
===Inspection===
The piston on the left in Fig. 1 came from a '96 SE turbo with a noisy balance chain which had to be cut and removed from the engine. Closeup pics show significant scoring, but the piston moved freely, and did not appear to stick inside the bore. If the piston shows excessive scoring, or no longer moves freely, it must be replaced.[[file:900_9-3_Oil_Pressure_Relief_3.jpg|thumbnail|none|Fig. 5 - Oil Pressure Relief Piston With Scoring]][[file:900_9-3_Oil_Pressure_Relief_4.jpg|thumbnail|none|Fig. 6 - Oil Pressure Relief Piston With Scoring]]
===Reassembly===
===References===
Haynes Ch. 2A-11.11
Saab EPC 2-0330
