N14 Base Engine Troubleshooting and Repair Manual – 007-041   Lubricating Oil Viscosity Sensor

Remove the oil transfer tube. Refer to Procedure 007-040.

Disconnect the pressure signal line (1) from the lubricating pump fitting.

Disconnect the rifle pressure supply line (3) from the oil rifle fitting (4).

Disconnect the viscosity sensor drain line from the cylinder block fitting.

Remove the two mounting bracket capscrews from the pan rail.

Remove the entire assembly from the engine.

Remove the hoses and bracket from the viscosity sensor.

1. Main oil rifle pressure.
2. Modified pressure signal to pressure regulator.
3. Return to oil pan.

Remove the viscosity sensor fittings (1) and (2), and filter screens (3).

Remove the viscosity sensor fitting (1), the injector orifice plug (3), and gasket (4).

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Use ultrasonic cleaners, Part Number 3376665 or 3375001, and ultrasonic cleaners solution, Part Number 33750003, to clean the viscosity sensor.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Use mineral spirits to neutralize the solution after cleaning.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Use compressed air to blow through each port to remove any debris.

Inspect the flex lines. Replace if plugged or restricted.

Inspect fittings (1) and filter screens (2). Replace if damaged or plugged screens.

Inspect the injector orifice plug (3) and gasket (4). Replace if damaged or restricted.

Install the filter screens (3) and screen retainers (4) in the viscosity sensor.

Install the fittings (1) and (2), with new o-rings (5), and tighten.

Lubricate the o-rings with clean vegetable oil.

Install the injector orifice plug (3) and gasket (4).

Lubricate the o-ring with clean vegetable oil.

Install the fitting (1), using a new o-ring (2) and tighten.

Install the bracket to the viscosity sensor. Install the two bracket capscrews and tighten.

Connect the flexible hoses to the viscosity sensor fittings.

Do not allow dirt or debris to enter the oil lines.

1. Main oil rifle pressure.
2. Modified pressure signal to pressure regulator.
3. Return to oil pan.

Install the entire assembly with flex hoses attached to the cylinder block pan rail.

Install the two capscrews and tighten.

Connect the sensor drain line (1) to the tee fitting on the cylinder block.

Connect the pressure signal line (1) to the lubricating pump fitting (2) and the rifle pressure supply line (3) to the oil rifle fitting (4).

Install the oil transfer tube. Refer to Procedure 007-040.

Operate the engine until the water temperature reaches 82°C [180°F], and check for leaks.

The viscosity sensor controls the oil pressure signal to the lubricating pump pressure regulator. It allows high oil rifle pressure with cold, thick oil, but normal oil rifle pressure with warm oil. The high oil pressure with cold viscous oil highly improves oil fill of the STC injector tappets. This provides maximum engine timing advancement and white smoke control. The sensor allows normal oil pressure when the oil is warm.

Connect an oil pressure gauge of known accuracy to the main oil rifle.

Operate the engine until the oil temperature stabilizes. Observe the oil rifle pressure as the temperature of the oil is increasing. compare results with the values given in the Effect of Viscosity Sensor on Main Oil Rifle Pressure table.

If the results do not agree with the Effect of Viscosity Sensor on Main Oil Rifle Pressure table, verify that the base engine lubricating system is operating properly before removing the viscosity sensor.

Verify the base engine lubricating system is functioning properly by isolating the viscosity sensor from the system.

Disconnect the viscosity sensor to lubricating pump line and the oil rifle-to-viscosity sensor line.

Plug both lines from the viscosity sensor.

Connect a pressure signal line from the oil rifle to the lubricating pump construct a flexible hose (1) of 305 mm [12 inch] to connect the main oil rifle (3) to the lubricating oil pump (2).

Operate the engine until the oil temperature stabilizes.

The temperature must be between 82°C [180°F] and 93°C [200°F].

Observe the oil rifle pressure as the oil temperatures rises.

Observe the oil pressure at the oil main rifle. The pressure must be as follows:

Oil pressure at idle (minimum allowable) 70 kPa [10 psi] at 93°C [200°F].

At no load governed speed: 240 to 310 kPa [35 to 45 psi].

If the pressure is within these specifications, the lubricating system is operating properly.