HOSE AS 3725905 - Caterpillar

Vehicular, Generator Set Engines So EquippedMagnetic pickups (speed sensors), installed in the flywheel housing, can be contaminated with metal filings. The metal filings can result from starter pinion and flywheel ring gear engagement. These metal filings can accumulate on the magnetic tip of the sensor. If the sensor is contaminated with metal filings, the signal from the sensor may be lost. The loss of sensor signals can result in the malfunction of the engine protection system, erratic engine operation, and/or random engine shutdowns.
Caterpillar recommends that engine speed sensors and crank angle sensors (magnetic pickups) be cleaned and reset to factory clearance dimension at the first oil change and every 4000 hours thereafter. The magnetic pickups should also be cleaned and recalibrated at the first oil change following the replacement of a starter, ring gear, or flywheel. The inspection interval can be changed depending upon the results of previous inspections, and the frequency and duration of the engine cranking.