Lubricating Oil System - Overview C Series Page F-10 Section F - Familiarization If a sending unit malfunction is found: Use a master gauge of known accuracy to verify the reading of the suspect gauge. Replace the sending unit if it is defective. Oil Temperature Thermostat NOTE: The oil temperature thermostat can not be checked in-chassis; it must be removed for testing; refer to Procedure 007-039. Oil Suction Tube A loose suction tube, damaged gasket, or crack in the suction tube can cause a temporary loss of prime for the oil pump. The engine will have low pressure or no oil pressure at starting, followed by normal or low pressure.
A steady decrease in oil pressure over a long period will be indicated by worn bearings or excessive oil pump wear. Refer to Procedure 007-051 to check for internal engine damage. Bearings and Oil Pump