Internal Oil Flow

455 / 403 Engine Lubrication System


Ref: Maintenance Manual X-7525 / Section 6 - Engine / Page 6A-2 / Engine Lubrication


NOTE: Red shows oil path leaving the engine and blue the return path.


The engine oil pan forms a reservoir for engine oil to provide lubrication and also hydraulic fluid to operate the valve lifters. Oil pressure for lubrication is furnished by a gear type oil pump that is bolted to the rear main bearing cap and driven by the camshaft gear through a hexagonal drive shaft. Oil enters the pump through a screened inlet located near the bottom rear of the oil pan.


The pressurized oil from the pump passes through the engine oil cooler located in the radiator tank then to the oil filter located on the right rear side of the engine block, see Figure 2. The oil filter base has a by-pass valve which in the event of filter restriction will open at 5.3 to 6.3 psi. It then enters the right oil gallery where it is distributed to the five main bearings. The right bank valve lifters receive oil from this gallery from eight feed holes that intersect the gallery.


The five camshaft bearings are lubricated from vertical passages intersecting the main bearing oil passages . At the front main bearing a third passage connects the right main oil gallery to the left gallery which then feeds the left bank of valve lifters.


The engine oil pressure warning light switch is connected to the front of the left oil gallery. The switch is calibrated to turn on the instrument panel warning light when engine oil pressure is too low. The switch, normally closed, is set to open at 2-6 psi.


The rear oil gallery plug has a .040" orifice to help purge contaminants from the gallery. At the front end of the right gallery, a small orifice sprays oil to lubricate the fuel pump eccentric cam and the timing chain.


The oil pump and distributor drive gear are lubricated by splash from the rear cam bearing and connecting rod bearings.


The rocker arms and valve tips are lubricated by means of oil furnished through the hydraulic lifters and hollow push-rods. A disc valve in the lifter meters oil to the push rods.


The connecting rod bearings are oiled by constant oil flow from passages drilled through the crankshaft connecting the main journals to the rod journals. A groove around each main bearing furnished oil to the drilled crankshaft passages.


Oil returns to the oil pan reservoir from the rocker arms through passages at each end of the cylinder heads. Oil from the valve lifter compartment returns through clearance holes in the lower portion of the compartment near the camshaft. The timing chain compartment drains directly into the oil pan.