Engine Oil System

TTP	B1-L3	ATA79
Cessna 172	B2-L1

Lubrication System. Maintenance

Replace external full flow oil filter element. (Check used element for metal particles.) Drain and renew lubricating oil.

Engines Not Equipped with External Filter. Remove oil pressure screen and clean thoroughly. Note carefully for presence of metal particles that are indicative of internal engine damage. Change oil every 25 hours.

Check oil lines for leaks, particularly at connections for security of anchorage and for wear due to rubbing or vibration, for dents and cracks

Oil Grades and Limitations – Service the engine  with the recommended grade oil

Oil Suction and Oil Pressure Screens – At each 100-hour inspection remove suction screen. Inspect for metal particles; clean and reinstall. Inspect and clean pressure screen every 25 hours.

Oil Pressure Relief Valve – Subject engines may be equipped with either an adjustable or nonadjustable oil pressure relief valve. A brief description of both types follows:

(1) Non-Adjustable Oil Pressure Relief Valve – The function of the oil pressure relief valve is to maintain engine oil pressure within specified limits. The valve, although not adjustable, may control the oil pressure with the addition of a maximum of nine (9) P/N STD-425 washers between the cap and spring to increase the pressure. Removal of the washers will decrease the oil pressure. Some early model engines use a maximum of three (3) P/N STD-425 washers to increase the oil pressure and the use of a P/N 73629 or P/N 73630 spacer between the cap and crankcase to decrease the oil pressure. Particles of metal or other foreign matter lodged between

the ball and seal will result in faulty readings. It is advisable, therefore, to disassemble, inspect and clean the valve if excessive pressure fluctuations are noted.

Oil Pressure Relief Valve (Adjustable) – The adjustable oil relief valve enables to maintain engine oil pressure within the specified limits. If pressure under normal operating conditions should consistently exceed the maximum or minimum specified limits, adjust the valve

With the engine warmed up and running at approximately 2000 RPM, observe the reading on the oil pressure gage. If the pressure is above maximum or below minimum specified limits, stop engine and screw the adjusting screw outward to decrease pressure or inward to increase pressure. Depending on installation, the adjusting screw may have only a screw driver slot and is turned with a screw driver; or may have the screw driver slot plus a pinned .375-24 castellated nut and may be turned with either a screw driver or a box wrench

Garmin G1000,  Oil pressure is shown on the Multi-Function Display (MFD).

(1) The table that follows is to be used with the troubleshooting chart.
CAUTION: Do not apply voltages that are more than the voltages shown in Table 101. Too much voltage can cause damage to the indicator.
CAUTION: Do not calibrate the oil pressure indicator without a calibrated pressure source.
NOTE: A test of the calibration for the oil pressure transducer (JN004) can be completed at a facility that has a calibrated pressure source. Table 101 can be used to do a check of the correct output of the transducer.

791001 Engine Oil - Drain oil sump and oil cooler.
Check for metal particles or foreign material in filter, on sump drain plug, and on engine
suction screen. Replace filter, and refill with recommended grade aviation oil. 05-12-13 120
792001 Oil Cooler - Check for obstructions, leaks, and security of attachment.