The oil pump is removed for replacement when its supply decreases, causing a constant drop in oil pressure in the engine lubrication system, as well as when oil leaks through the seal of the mating surfaces of the pump body and cylinder block. Only the pump assembly is supplied as spare parts, therefore this section describes only the removal and installation of the pump.
To repair the oil pump, you need a set of new spare parts, which are not available separately at retail. Therefore, if the pump fails, replace it as a whole or contact a specialized service for repair.
1. Disconnect the wire from the negative terminal of the battery.
2. Drain the cooling system (see "Replacing the coolant").
3. Remove the accessory drive belts (see "Replacement of auxiliary drive belts").
4. Remove the power steering pump (see "Removal and installation the power steering pump").
5. Remove the timing belt...
6. ...and the tension roller (see "Replacing the timing belt").
WARNING: After removing the timing belt, do not turn the crankshaft or camshafts, as the pistons may damage the valves.
7. Remove the toothed pulley from the crankshaft end.
8. Remove the two bolts securing the water distribution pipe to the water pump.
NOTE: For clarity, the exhaust manifold has been removed.
WARNING: The water distribution pipe flange is sealed with a rubber ring. Replace this ring each time the connection is disassembled.
9. Remove the three bolts securing the oil pan to the oil pump...
10. ...nine bolts securing the oil pump to the engine cylinder block...
NOTES: Please note that the oil pump mounting bolts vary in length (bolts A are short, bolts B are long). For clarity, shown on a removed engine.
11. ...and remove the oil pump assembly with the water pump.
NOTE: Shown with engine removed for clarity.
12. Remove the sealing gasket installed under the oil pump housing flange.
NOTE: Replace the oil pump gasket with a new one each time the joint is disassembled, as the old gasket may not provide a tight seal when reinstalled.
HELPFUL TIP: Replace the front crankshaft oil seal whenever the pump is removed. See "Replacing crankshaft seals").
13. Install the pump in the reverse order of removal and tighten its mounting bolts evenly crosswise to a torque of 20 N·m.
14. Install all previously removed parts and fill with coolant, see. "Replacing the coolant").
HELPFUL TIP: When installing a new oil pump, we recommend replacing the oil filter element.
(The article is based on data from the website: «ChevyMan»)