Engine Lubrication: Description and Operation

Legend
- 1 Oil pump
- 2 Relief valve
- 3 Oil thermostat
- 4 Piston cooling nozzle
- 5 Spring loaded piston type valve
- 6 Compressor shaft
- 7 Drilled oil way from main oil way

Lubrication System
The high output of the engine has imposed greater demands on its lubrication system and cooling. The following modifications have been made:
- Oil pump (1) capacity has been increased by using a wider, differently shaped impeller.
- The reducer valve (2) has a stronger spring and opens at six bar (instead of the B5254's five bar).
- An oil thermostat (3) regulates oil flow to the cooler. The oil thermostat opens at approx. 95°C (203°F) and is fully open at an oil temperature of approx. 150°C (302°F).
- Piston cooling nozzles (4) direct oil onto the underside of the pistons. Oil is supplied to these nozzles from the main bearing oil supply passages and flows through spring loaded valves (5) which open at two bar oil pressure so as to maintain satisfactory oil pressure at low Rpm when piston cooling is not necessary. Common ball valves are used for cylinders 2-3 and cylinders 4-5 while cylinder 1 has its own valve.
- Compressor shah (6) lubricating oil is supplied via an oil way drilled into block (7) from the main oil way in the cylinder block. The return oil way is connected to the sump.

Oil Capacity
Oil change and filter replacement: 5.3 l (5.6 US qt.)
Engine dry after reconditioning: 6.2 l (6.6 US qt.)
(if the oil cooler, which contains about 0.91 has been drained).