MUFFLER AS 7W3659 - Caterpillar

Low Oil Pressure
Table 1
Required Tools    
Tool     Part Number     Part Description     Qty    
A     4C-4890     Hydraulic Test Group     1    The following conditions will cause low oil pressure.
The oil level is low in the crankcase.
A restriction exists on the oil suction screen.
Connections in the oil lines are leaking.
The connecting rod or the main bearings are worn.
The rotors in the oil pump are worn.
The oil pressure relief valve is operating incorrectly.A worn oil pressure relief valve can allow oil to leak through the valve which lowers the oil pressure. Refer to Specifications, "Engine Oil Relief Valve" for the correct operating pressure and other information.When an engine that is turbocharged runs at the normal temperature for operation and at high idle, the oil pressure must be a minimum of 280 kPa (40 psi). A lower pressure is normal at low idle.Use Tooling (A) in order to test the pressure of the lubrication system.High Oil Pressure
High oil pressure can be caused by the following conditions.
The spring for the oil pressure relief valve is installed incorrectly.
The plunger for the oil pressure relief valve becomes jammed in the closed position.
Excessive sludge exists in the oil which makes the viscosity of the oil too high.