Oil Pump

Complete removal and replacement of the oil pump on a 1966 Chevrolet Corvette 327ci V8, requiring engine oil pan removal and crankshaft access.

Warnings

Tools required

Parts

• Oil pump assembly with pickup tube × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Timing cover seal × 1 — Use OEM specification
• Oil pump mounting bolt × 1 — 5/16"-18 x 3/4"
• Oil pickup tube O-ring × 1 — Use OEM specification
• RTV silicone sealant (high-temp) × 1 — Use OEM specification

Fluids

• 5W-30 Conventional Engine Oil — 5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable
3. Raise front of vehicle and support securely on jack stands placed under frame rails
4. Remove engine oil drain plug and drain all engine oil into appropriate container
5. Allow engine to cool completely if recently operated

Procedure

1. 1

   Remove oil pan
   Remove all oil pan bolts (14 bolts total around perimeter). Carefully break the gasket seal using a gasket scraper or pry bar at the rear corners of the pan. Lower the oil pan away from the engine block. If the pan is stuck, gently tap with a rubber mallet to break the seal. Note the location of any different length bolts for reassembly.
2. 2

   Remove radiator and accessories
   Drain coolant from radiator into appropriate container. Disconnect upper and lower radiator hoses. Remove radiator shroud bolts and remove shroud. Remove radiator mounting bolts and lift radiator out of engine bay. Remove fan belts by loosening alternator and power steering pump adjustments.
3. 3

   Remove harmonic balancer
   Using a breaker bar and appropriate socket, remove the single center crankshaft bolt from the harmonic balancer. Before removing the balancer, mark the position of the balancer relative to the crankshaft timing marks with a paint pen or scribe for proper reinstallation. Install harmonic balancer puller and carefully extract the balancer from the crankshaft. Do not use a jaw puller on the outer ring as this can separate the inertia ring from the hub.
4. 4

   Remove timing cover
   Remove the timing cover bolts (7 bolts total). Carefully pry the timing cover away from the block using a gasket scraper at the designated pry points. Remove the timing cover and gasket. Inspect the timing chain and sprockets for wear while exposed; replace if necessary though this is beyond the scope of this oil pump replacement procedure.
5. 5

   Remove oil pump
   Locate the oil pump mounted to the rear main cap area, driven by the distributor shaft. Remove the single oil pump mounting bolt that secures the pump body to the rear main bearing cap. Carefully pull the oil pump assembly straight down and out, disengaging it from the distributor drive shaft. The pump pickup tube will come out with the assembly. Verified detail (The SBC oil pump is retained by a single 3/8"-16 bolt, not a 5/16"-18 bolt as listed in the parts. The 5/16 spec appears incorrect for the oil pump-to-main-cap fastener.): Oil pump mounting bolt (3/8"-16)
6. 6

   Inspect and prepare new pump
   Inspect the oil pump mounting surface on the rear main cap for damage or debris. Clean thoroughly with solvent and a wire brush. Inspect the distributor drive shaft for wear or damage. Install new O-ring on the pickup tube of the new oil pump. Pack the new oil pump with petroleum jelly or assembly lube to ensure it primes quickly on first startup. Rotate the pump shaft by hand to distribute lubricant throughout internal gears.
7. 7

   Install new oil pump
   Carefully guide the new oil pump assembly up into position, aligning the pump drive shaft with the distributor drive shaft tang. The shaft has a specific orientation and will only engage one way. Rotate the pump slightly while pushing up until it fully seats against the rear main cap. Install the single oil pump mounting bolt and tighten to specification. Ensure the pickup tube is positioned correctly in the oil pan area and not contacting any other components.
8. 8

   Install timing cover
   Clean all old gasket material from the block and timing cover mating surfaces using a gasket scraper. Apply a thin bead of RTV silicone at the block-to-oil pan junction on both sides where the timing cover meets the pan rail. Install the new timing cover gasket and position the timing cover onto the block, ensuring the crankshaft seal is properly aligned with the crankshaft snout. Install all 7 timing cover bolts and tighten in a crisscross pattern to ensure even sealing.
9. 9

   Install harmonic balancer
   Clean the crankshaft snout and the inside bore of the harmonic balancer with solvent. Apply a thin coat of clean engine oil to the crankshaft seal surface. Align the harmonic balancer with the marks made during disassembly to maintain proper timing reference. Slide the balancer onto the crankshaft, then install the center bolt. Tighten the crankshaft bolt to specification while preventing crankshaft rotation by placing the transmission in gear or using a balancer holding tool.
10. 10

    Prime oil pump
    Remove the distributor from the engine. Insert the oil pump priming tool (5/16" hex shaft) into the distributor hole, engaging it with the oil pump drive shaft. Using an electric drill, rotate the priming tool clockwise (viewed from above) until oil pressure is observed at the oil pressure sending unit or oil flows from the rocker arms if valve covers are removed. Prime for 20-30 seconds minimum. This ensures the pump is filled and oil galleries are charged before engine startup.
11. 11

    Install oil pan
    Clean all old gasket material from the oil pan and engine block mating surfaces thoroughly. Apply a thin bead of RTV silicone at the front and rear corners where the timing cover and rear main cap meet the block (1/4" bead at each corner). Position the new oil pan gasket and align the oil pan to the block. Install all 14 oil pan bolts hand-tight first, then tighten in a crisscross pattern from center outward to ensure even gasket compression and prevent leaks.
12. 12

    Reinstall cooling system components
    Reinstall the radiator into the mounting brackets and secure with mounting bolts. Reconnect upper and lower radiator hoses and secure with clamps. Install radiator shroud and secure with bolts. Reinstall and tension all drive belts for alternator, power steering pump, and water pump by adjusting component positions.
13. 13

    Refill fluids
    Install oil drain plug with new crush washer if applicable. Fill engine with 5 quarts of 10W-30 or 10W-40 conventional engine oil through the valve cover oil fill cap. Refill cooling system with conventional ethylene glycol coolant mixed 50/50 with water (approximately 16-17 quarts total system capacity). Reconnect negative battery cable.

Reassembly

1. Reinstall distributor ensuring correct rotor position and timing alignment
2. Double-check all bolt locations and tightness before starting engine
3. Verify no tools or parts are left in engine bay
4. Lower vehicle from jack stands after confirming all work underneath is complete

Verification

• Start engine and immediately verify oil pressure gauge shows normal pressure within 5-10 seconds
• Check for oil leaks around oil pan gasket and timing cover while engine is running
• Allow engine to reach normal operating temperature and recheck for leaks
• Check oil level on dipstick after engine reaches operating temperature and adjust if necessary
• Verify cooling system has no leaks and coolant level is correct
• Road test vehicle and recheck oil level and pressure after 50-100 miles of operation

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