TM 5-3895-346-14
ENGINE OVERHAUL
LUBRICATING OIL PRESSURE REGULATOR
LUBRICATING OIL PRESSURE REGULATOR
Stabilized lubricating oil pressure is maintained within the engine at all speeds, regardless of the oil
temperature, by an oil pressure regulator valve installed in the engine lower front cover as shown in Fig. 1. The
oil pressure regulator consists of a hollow piston-type valve, a spring, gasket, and plug. The valve is located in
an oil gallery within the lower front cover and is held tight against a counterbored valve seat by the valve spring
and plug. When the oil pressure exceeds a given value (Table 1), the valve is forced from its seat and the
lubricating oil is bypassed into the engine oil pan. Under normal conditions, the pressure-regulator valve
should require very little attention. If sludge accumulates in the lubrication system, the valve may not work
freely, thereby remaining open or failing to open at the normal operating pressure.
Figure 1. Location of Current Oil Pressure Regulator Valve
TABLE 1
Valve Opening
Engine
Front Cover
Pressure
psi
kPa
Former
78
538
In-line
Current
51
352
Whenever the lubricating oil pump is removed for inspection, the regulator valve and spring should also be re-
moved, thoroughly cleaned in fuel oil and inspected.
Remove Oil Pressure Regulator
1. Remove the plug and washer from the engine lower front cover.
2. Withdraw the spring and the valve from the cover.
Inspection
Clean all of the regulator components in fuel oil and dry them with compressed air. Then inspect the parts for
wear or damage. The regulator valve must move freely in the valve bore. If the valve is scored and cannot be
cleaned up with crocus cloth, it must be replaced. Replace a fractured or pitted spring.
Install Oil Pressure Regulator
1. Apply clean engine oil to the outer surface of the valve and slide it into the opening in the engine lower front
cover, closed end first.
2. Install a new copper gasket on the plug.
3. Insert the spring in the valve.
4. While compressing the spring, start the plug in the side of the cover, then tighten the plug.
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