Oil Pressure Sending Unit Replacement
Procedure for replacing the oil pressure sending unit on the 944, including power steering pump access notes for turbocharged cars, crush washer specification, torque value, and terminal orientation.
Tools Needed
- 15/16" (or 24 mm) stubby open-end wrench — thin head if possible
- Metric socket set
Procedure
- Disconnect the battery negative lead.
- Place the car on jack stands.
- From underneath the car, remove all skid/belly pans covering the bottom of the engine.
Note: On normally-aspirated cars, the power steering pump may not need to be removed to access the oil pressure sending unit. On turbocharged cars and normally-aspirated 944s fitted with an external oil cooler, the additional oil cooler lines obstruct access sufficiently that the power steering pump must be moved out of the way.
- Disconnect the power steering pump (leave all lines attached) and hang it out of the way. Remove the belt tension adjusting turnbuckle without changing the adjustment — this allows the pump to be reinstalled without re-adjusting the belt.
- Disconnect the two wire leads from the oil pressure sending unit (located just below the oil filter).
Note — Crush Washer: When replacing the sending unit, use a new crush washer. An M18 × 24 aluminium or copper crush washer is required. (The factory parts catalogues do not list a crush washer for this unit, but one is present on every car in practice.)
- Using a 15/16" or 24 mm stubby open-end wrench, loosen the oil pressure sending unit. Have catch rags ready. Have the new sending unit ready to install immediately to minimise oil loss.
- Remove the old sending unit and immediately insert the new one. Torque the sending unit to 35 Nm (25 ft-lbs). This requires a 24 mm (15/16") open-end crow's foot for a torque wrench. If a crow's foot is unavailable, tighten until snug — do not overtighten or the seal ring will be damaged. A new seal ring should prevent leaks.
- Reconnect the wires to the terminals of the new sending unit.
Note — Terminal Orientation: The sending unit has two terminals. Normally one is a straight post and the other has a spade connector. New sending units sometimes have spade connectors on both posts. Use the old sending unit as a reference to determine correct orientation. If the terminals are reversed, the gauge will read pegged high and the low oil pressure warning light will flicker at idle.
- With the wires connected, reconnect the battery negative lead and start the car to verify proper gauge operation.
- Reinstall the belly pans and lower the car from jack stands.