Comprehensive Guide to the Oil Pressure Switch for Harley Davidson Motorcycles

What is the Role of the Oil Pressure Switch in Harley Davidson Motorcycles?

The oil pressure switch in a Harley Davidson motorcycle is a critical component that monitors the engine’s oil pressure and alerts the rider to any potential issues. The switch is responsible for activating the oil pressure warning light on the dashboard when the oil pressure falls below a certain threshold. This ensures the rider is alerted to potential engine damage due to low oil pressure. The switch typically operates by completing a circuit to ground when the oil pressure is sufficient, thus turning off the warning light. When the oil pressure drops, the circuit is broken, and the warning light illuminates.

What are the Common Specifications and Issues with the Oil Pressure Switch?

The oil pressure switch in Harley Davidson motorcycles can have different thread types. Early models may have 3/8-24 threads, while later models often use 1/8 NPT threads. This difference can necessitate the use of adapter fittings during installation or replacement. Common issues with the oil pressure switch include incorrect thread types, faulty switches, and wiring issues. Ensuring the correct thread type and proper installation is crucial for the switch to function correctly.

How to Install an Oil Pressure Gauge on a Harley Davidson?

To install an oil pressure gauge on a Harley Davidson, you will need the following tools and materials:

1. Oil Pressure Gauge Kit (specific to your model year and type)
2. Adapter fittings (if necessary)
3. Teflon tape or LOCTITE pipe sealant
4. Socket wrench or ratchet and socket set
5. Torque wrench

The installation process involves the following steps:

1. Locate the mounting location for the gauge, typically on the right side of the gearcase next to the rear tappet guide housing.
2. Remove the existing components, including the cap, O-ring, screen spring, and screen from the gearcase. Ensure the oil screen mesh is clean and not plugged.
3. Reinstall the oil screen spring and screen, bending the top of the screen into a “V” shape to fit the adapter fitting.
4. Install the new O-ring on the adapter plug and tighten it to 3 ft-lbs.
5. Install the 45° fitting and then the gauge, ensuring it is correctly positioned and not overtightened.
6. Use teflon tape or LOCTITE pipe sealant on all threads except the adapter plug to prevent clogging.

How to Replace the Oil Pressure Switch on a Harley Davidson?

To replace the oil pressure switch on a Harley Davidson, you will need the following tools and materials:

1. New oil pressure switch (correct thread type for your model)
2. Socket wrench or ratchet and socket set
3. Torque wrench
4. Adapter fittings (if necessary)

The replacement process involves the following steps:

1. Locate the oil pressure switch, typically near the oil pump.
2. Disconnect the wiring from the old switch, noting the wiring configuration to ensure correct reconnection.
3. Remove the old switch by unscrewing it from the oil pump. If the threads are different, use an adapter fitting.
4. Install the new switch, ensuring it is securely fastened. Use an adapter fitting if necessary.
5. Reconnect the wiring to the new switch, ensuring the correct connections are made.

The cost of a new oil pressure switch can range from $20 to $50, depending on the model and source. The replacement process typically takes about 30 minutes to an hour, depending on the complexity and the need for adapter fittings. Potential challenges include ensuring the correct thread type and proper wiring connections.

How to Troubleshoot an Oil Pressure Warning Light on a Harley Davidson?

To troubleshoot an oil pressure warning light on a Harley Davidson, follow these diagnostic steps:

1. Check the bulb and wiring:
2. Ensure the warning light bulb is functioning.

3. Verify that the wiring from the switch to the bulb is intact.

4. Check the switch functionality:

5. Test the oil pressure switch by applying air pressure to the switch and measuring the voltage output.

6. The switch should ground the circuit when sufficient pressure is applied.

7. Check the oil pressure:

8. Verify that the engine oil pressure is within the recommended range.
9. Low oil pressure can trigger the warning light.

Possible root causes for the oil pressure warning light include a faulty switch, incorrect thread type, or wiring issues. To address these issues, you can replace the switch, check and repair the wiring, or adjust or replace any adapter fittings as needed.

Reference:
1. Oil pressure switch | V-Twin Forum
2. Oil Pressure Switch threads – The Panhead & Flathead Site
3. TESTING OIL PRESSURE SWITCH – The Panhead & Flathead Site