Oil Pressure Diagnosis and Testing. GMC Truck Jimmy

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2002 🢒 Jimmy - 2WD 🢒 Engine 🢒 Engine Mechanical - 4.2L 🢒 Oil Pressure Diagnosis and Testing

The following can cause low or no oil pressure:

•	Low oil level -- fill to the full mark on the oil level indicator.

•	Slow idle speed

•	Incorrect or malfunctioning oil pressure switch -- replace the oil pressure switch.

•	Incorrect or malfunctioning oil pressure gage -- replace the oil pressure gage.

•	Improper oil viscosity or diluted oil

-	Install oil of proper viscosity for expected temperature.

-	Install new oil if it is diluted.

•	The oil pump is worn or dirty -- clean or replace the oil pump.

•	The oil filter is plugged -- replace the oil filter.

•	The oil pickup screen is loose or plugged -- replace the oil pickup screen.

•	A hole in the oil pickup tube -- replace the oil pickup tube.

•	Excessive bearing clearance -- replace the bearings.

•	Cracked, porous, or plugged oil galleries -- repair or replace the engine block.

•	The gallery plugs are missing or improperly installed -- install or repair as necessary.

•	The pressure regulator valve is stuck.

-	Check the pressure regulator valve for sticking in the bore.

-	Check the bore for scoring and burrs.

•	The camshaft is worn or poorly machined -- replace the camshaft.

•	Worn valve guides -- repair as needed.

•	J 21867 Pressure Gauge and Hose

•	J 42907 Oil Pressure Tester Adapter

If the vehicle has low oil pressure perform the following tests.

Check the oil level.
Raise the vehicle and remove the oil filter.
Assemble the plunger valve in the large hole of J 42907 (1) base and the hose in the small hole of J 42907 (1) base. Connect the J 21867 (2) to the end of the hose.
Insert the flat side of the rubber plug in the bypass valve without depressing the bypass valve itself.
Install J 42907 (1) on the filter mounting pad.

Start the engine and check the overall oil pressure and the oil pressure switch. The engine should be at operating temperature before checking the oil pressure. The oil pressure should be approximately 85kPa (12 psi) at 1200 rpm using 5W30 engine oil.
If adequate oil pressure is indicated, check the oil pressure switch.
If a low reading is indicated, press the valve on the tester base to isolate the oil pump and/or its components from the lubricating system. An adequate reading at this time indicates a good pump and the previous low pressure was due to worn bearings, etc. A low reading while pressing the valve would indicate a faulty pump.