Engine Lubrication: Description and Operation

Lubricating system





General
Engine oil is used not only to lubricate and cool the engine, but also for the operation of the CVCP mechanism. The oil sump is made of cast aluminum and has a lower and an upper baffle plate, a so-called windage tray. The oil level switch is mounted in the sump. The oil pump is a complete unit mounted in the cylinder block behind the cam timing cover. The oil cooler is mounted on the cylinder block while the front of the engine houses the filter housing and oil pressure switch. It is vital that the oil change intervals specified in the Saab Service program are followed to ensure that all engine components reach their full service life and that engine performance is optimal. Servicing must be carried out when one of the criteria - service message, distance or time - is met. It is also vital that oil complying with specification GM-LL-A-025 is used.





Oil sump
The oil sump is cast of an aluminum allow in a power version that reduces noise. The sump has a lower baffle plate to control oil movements and prevent the oil pump from sucking in air. To reduce crankshaft friction loses, the sump is also equipped with an upper baffle plate, a so-called "windage tray". This plate reduces the amount of oil drawn in with the crankshaft rotations, which in turn reduces friction. A oil level switch is mounted in the oil sump.








Oil pump
Engine lubrication is handled by a pressure lubricating system in which oil pressure is generated by a gear pump (a gerotor pump) consisting of a pump housing with cover, gear and a centrally displaced gear ring. The pump housing is mounted in the cylinder block behind the cam timing cover and is driven directly by the crankshaft. The pressure relief valve is located in the pump housing. The oil pump sucks in oil from the sump via a pipe. The oil is lead in the gear pump and is then forced out via a duct in the engine to the heat exchanger. Once the oil has passed the heat exchanger, it is filtered in the oil filter.








Oil filter
The engine is equipped with an oil filter order to prevent wear and engine damage from particles and to reduce engine wear. The filter is an insert filter. The filter cartridge should be changed as specified in the Service program. In the event of a filter clog, an overflow valve in the oil filter holder cover opens. The oil then passes without being cleaned. This is a safety feature since oil circulation is vital under all conditions.





Heat exchanger
In order to maintain a uniform engine oil temperature, it passes through a heat exchanger. When a cold engine is started, the coolant warms up the engine oil. Conversely, if the engine is driven with a high load, i.e. the engine oil is warmer than the coolant, the heat exchanger cools the engine oil. The heat exchanger is mounted together with the oil filter on the cylinder block on the back of the engine.