Series 50 – Section 3.4 Oil Pressure Relief Valve

Section 3.4
Oil Pressure Relief Valve

Oil leaving the pump under pressure passes into the pressure relief valve body. The spring-loaded valve opens when the pressure exceeds 690 kPa (100 lb/in.² ) and directs the excess oil to the oil pan. The pressure relief valve is mounted on the oil outlet adaptor in the balance support assembly.‪

The pressure relief valve consists of a valve body, a hollow piston-type valve, spring, spring seat and pin to retain the valve assembly within the valve body.‪

The relief valve assembly used is composed of the same parts as the regulator valve assembly with the exception of the body. See Figure "Oil Pressure Regulator and Relief Valve Details" .‪

Note: The valve body has two retaining pin holes. Install the pin in the outermost hole for the regulator valve. The retaining pin must be positioned correctly so the proper valve opening pressure will be obtained. Although the same casting is used for both the pressure regulator and relief valves, the regulator valve has a slightly larger opening machined into the side. See Figure "Comparison of Pressure Regulator and Relief Valve Assemblies" .

The spring in the relief valve assembly is the same as used in the oil pressure regulator assembly.‪

Section 3.4.1
Repair or Replacement of Oil Pressure Relief Valve

To determine if repair is possible or replacement is necessary, perform the following procedure. See Figure "Flowchart for Repair or Replacement of Oil Pressure Relief Valve " .‪

Figure 1. Flowchart for Repair or Replacement of Oil Pressure Relief Valve

Section 3.4.2
Cleaning and Removal of Oil Pressure Relief Valve

Precleaning is not necessary.‪

Remove the oil pressure relief valve as follows:‪

1. Drain the lubricating oil and remove the oil pan. Refer to "3.9.2 Cleaning and Removal of Oil Pan" .
2. Remove the two bolts and washers securing the relief valve to the balance support.
3. Tap the oil pressure relief valve body lightly to loosen it from the balance support.
4. Remove the oil pressure relief valve and gasket.

Section 3.4.3
Disassembly of Oil Pressure Relief Valve

Disassemble the oil pressure relief valve as follows:‪

1. Clamp the oil pressure relief valve in the soft jaws of a bench vise.

   EYE INJURY ‪
   To avoid injury from flying parts when working with components under spring tension, wear adequate eye protection (face shield or safety goggles).‪

2. Depress spring seat and holt it securely while removing the spring seat retaining pin from the oil pressure relief valve body.
3. Remove the spring seat, spring and valve from the oil pressure relief valve body.

Section 3.4.3.1
Inspection of Oil Pressure Relief Valve

Clean the oil pressure relief valve prior to inspection as follows:‪

1. Clean all of the oil pressure relief valve components in fuel oil.

   EYE INJURY ‪
   To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.‪

2. Dry the components with compressed air.

Inspect the oil pressure relief valve as follows:‪

1. Inspect the oil pressure relief valve for movement.
   1. Check to see if the oil pressure relief valve moves freely in the valve body.
   2. If relief valve binds, replace it with a new part.
2. Inspect the components for wear or damage.
   1. Check to see if valve or the valve body are scored.
   2. If the valve and valve body parts cannot be cleaned up with a fine emery cloth, replace with new parts.
3. Inspect spring for following:
   1. Check for pitting or fractures.
   2. If spring is damaged, replace it with a new part.

Section 3.4.4
Assembly of Oil Pressure Relief Valve

Assemble the relief valve as follows:‪

1. Apply clean engine oil to the outer face of the valve.
2. Slide it into the oil pressure relief body, closed end first. See Figure "Oil Pressure Regulator and Relief Valve Details" .
3. Insert the spring in the valve and install the spring seat.

   NOTICE:
   The retaining pin must be positioned correctly so the proper valve opening pressure will be obtained. Although the same casting is used for both the pressure regulator and relief valves, the regulator valve has a slightly larger opening machined into the side. See Figure "Comparison of Pressure Regulator and Relief Valve Assemblies" .‪

4. While compressing the spring, install the retaining pin behind the spring seat.
5. Press the pin flush to 0.254 mm (0.010 in.) below the surface of the valve body.

Section 3.4.5
Installation of Oil Pressure Relief Valve

Install the oil pressure relief valve as follows:‪

1. Remove all traces of old gasket material from the mating surfaces of the oil pressure relief valve body and the balance support.
2. Secure the oil pressure relief valve assembly to the balance support with two bolts. Torque the bolts to 30-38 N·m (22-28 lb·ft).
3. Refer to "11.1.2 Lubrication System" for verification of proper oil pressure relief valve installation.