SHEET AS 3967684 - Caterpillar

Illustration 1. Test location for governor oil pressure and location of orifice.2. Check the engine oil pressure. Acceptable oil pressures are 205 25 kPa (30 5 psi) at 800 rpm and 380 35 kPa (55 5 psi) at 2000 rpm.These pressures are increased to 620 to 690 kPa (90 to 100 psi) by the governor oil booster pump. See Illustration 2.
Illustration 2. Location of by-pass valve and oil booster pump for governor.3. If low oil pressures are found in Steps 1 or 2, the cause of these must be found and corrected. Some possible causes are: a. A restriction in the oil flow, such as a plugged orifice in the fuel transfer pump housing. See Illustration 1. This orifice is a passage for oil into the governor oil booster pump. The diameter of this orifice must be 1.57 mm (.062"). If this diameter is too large, the other components in the servo mechanism will not get enough oil.b. A failure of the governor oil booster pump.c. By-pass valve does not operate. The valve may be held open.