Lubrication System : Low Pressure
Power Stroke 7.3 Liter Diesel Engine Low Pressure Oil Flow
- High-pressure oil pump reservoir
- Cylinder block
- Anti-drain check ball cap
- O-ring seal
- Check ball
- Valve lifter oil galleries
- Piston cooling oil jet
- Turbocharger oil return gallery
- Turbocharger oil supply gallery
- Pressure relief/regulator valve
- Oil filter bypass drain
- Main oil gallery
- Oil cooler
- Oil cooler header
- Oil pump screen cover and tube
- Gerotor oil pump
- Engine front covers
The Power Stroke 7.3 Liter Diesel engine lubrication system is comprised of a low-pressure system and a high-pressure system. The low-pressure system provides primary engine lubrication while the high-pressure system provides the hydraulic pressure required to actuate the fuel injectors.
The low-pressure lubricating system draws oil from the engine oil pan through the oil pump screen cover and tube into the oil inlet passage in the front cover. The gerotor oil pump then pumps the oil back out through the outlet passage in the front cover.
The oil separates into two paths.
One flow path sends oil into the high-pressure pump reservoir initial fill gallery (integral to the cylinder block) and through the anti-drainback check ball. During cold start the oil feeds in two directions from the anti-drainback check ball. One feed leaves the check ball and enters the front cover. From there it enters the high-pressure oil reservoir. The second feed exits the check ball and enters the left bank valve lifter oil gallery.
After leaving the front cover outlet passage, the second oil path sends the oil through the oil cooler and filter assembly. Once inside the filter housing, the oil filter bypass valve may open to vent excess pressure and oil back into the oil pan. After the oil has been circulated through the oil filter, the oil feed then enters the main oil gallery (integral to the cylinder block). Once in the main oil gallery, the oil is routed to the five crankshaft main bearings through five drilled and machined feed galleries (integral to the cylinder block). The five camshaft bearings receive the oil feed through five vertically drilled and machined feed galleries connected to the main bearing feed galleries. The front main bearing feed gallery also supplies oil to the right bank valve lifter oil gallery through a vertically drilled and machined oil feed gallery (integral to the cylinder block). The rear main bearing oil feed gallery also supplies oil to the turbocharger assembly through a vertically drilled and machined oil feed gallery (integral to the cylinder block).
Pressurized oil entering the turbocharger assembly is utilized to lubricate the compressor/turbine shaft. The oil drains back through the turbocharger mounting pedestal and back into the oil pan. The valve lifter oil gallery supplies pressurized oil to the valve tappets and to the piston cooling oil jets. Oil from the valve tappets is routed upward to the cylinder head valve train through hollow push rods. Once in the cylinder head, the oil drains back to the oil pan through return ports at each end of the cylinder head.