Harley-Davidson Engine Oil Pressure: Installing a Dial Gauge

• Lubricate, creating a sliding film between the moving parts in contact
• Cool, absorbing part of the heat generated in the engine
• Clean, removing combustion residues and metal or plastic shavings
• Pressurize hydraulic elements such as tappets, tensioners, etc., allowing them to function correctly.

Pressurized system
The oil circulates through all the passages, pushed by the pump, whose job is to maintain constant pressure while the engine is running. This pressure can vary due to temperature, when the oil's viscosity changes, and increases with engine speed (for this reason, it's advisable not to lower the idle speed too much, as this can lead to a loss of pressure in critical areas).
To be able to visualize the correct operation of the system, we will install a pressure indicator gauge from the manufacturer Arlen Ness, performing the operation on a Twin Cam Softail.

The indicator needle is immersed in a silicone liquid to dampen vibrations; the air bubble is necessary to allow for temperature variations.

Installing the clock
Installing the kit is very simple. We'll start by mounting the metal hose on the base of the clock. It's recommended to use liquid Teflon to properly seal the joints.

We will continue mounting the clock on its stand and lightly tightening the retaining screw so that it does not move.

The next step is to loosen the 2 bolts on the rear cylinder rocker cover and then mount the bracket directly using the new bolts provided in the kit, carefully tightening them to 23 Nm.

Making the connections
With the indicator in place, we will then look for the oil pressure sensor , which is located at the bottom front of the right crankcase, and proceed to remove it.

Once we have the sensor out of the engine, we will screw it (remember to use Teflon to seal the joint) to the adapter provided in the kit.

In the next step, we reinstall the sensor in the crankcase, tightening it to 14 Nm. With this step completed, we'll connect the clock hose to the new adapter.

The kit includes a hose retaining clip. It must be installed on the bolt holding the rear cylinder's hydraulic tappet cover. Its tightening torque is 12 Nm.

System check
With the new pressure gauge installed, we can now check if it's working properly. To do this, start the engine and check that the engine oil pressure light goes off after a few seconds.

We'll take a short drive until the engine reaches normal operating temperature (around 110°C), after which we'll check that the oil level is correct, adding more if necessary. Under these conditions, the gauge reading should be 5-10 psi with the engine idling and 20-38 psi with the engine at 2000 RPM.

It should be noted that these pressures will be significantly higher when the engine is cold and will drop slightly at high operating temperatures.

Frank Burguera

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