Oil pressure testing

Oil pressure testing is another strong indication of your engines overall internal health. Just as blood pressure can be used to determine the health of a human being.

The oil pressure test is used to determine the wear of an engine's internal parts. The testing procedure is performed with a mechanical gauge that measures the pressure of the oil as it circulates through the engine.

Basically, the pressure of the oil depends on the efficiency of the oil pump, along with the clearances through which the oil will flow.

Excessive clearance is most often caused by worn bearings and will cause a decrease in oil pressure. The most common worn bearings would be either the crankshaft main bearings or the connecting rod bearings. In some cases I have also seen worn camshaft bearings cause a low oil pressure reading.

Reasons for oil pressure testing

A loss of engine performance, flickering pressure warning light, excessive engine noise, and even poor starting can be caused by abnormal or low oil pressure.

When the engines oil pressure is too low, premature wear of its internal parts can be one of the results. Any of the above listed problems mentioned will cause me to break out my mechanical pressure gauge and get a reliable reading.

Personally I do not trust the oil pressure gauge on the dash. This is because there is a lot of room for error between the electronic sending unit and the gauge itself.

Oil pressure testing procedure

Remember if you do not have a good connection you may have a large mess to clean up. I use Teflon tape on the connection fittings. You should also look up the specifications for your engines pressure in a car repair manual.

Also note that the pressure is read when the engine is at normal operating temperature and results are recorded at idle speed, and usually around 2000 RPMs.

Excessive bearing clearances are not the only possible causes for low oil pressure readings. Sometimes they can be oil pump related problems. An example would be a restricted pump pickup screen.

This can be commonly blocked by sludge from lack of maintenance. Also note that a week or broken pressure relief valve, low oil level, contaminated oil, or even a low viscosity oil (wrong weight) can all cause low-pressure readings.

Give this engine diagnosis and oil pressure testing page a bookmark.

Learn the theory and operation as well as advanced testing procedures on my page about automotive engine repair

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