🔋 Sierra Medium Oil Pressure Sender, 18-5899 Review

Bought to replace my 3.0 Mercruiser, the oil pressure was 80psi (very high) and I knew the engine ran fine. Sensor replaced and sensor repaired, installation takes 5 minutes.

Choose a cheap option and take the risk of buying a used one. Before installing I measured the resistance at 0 PSIG and got 0.9 ohms. It should be 240 ohms. I'm glad I tested it first. Maybe that's why it was an earlier comeback? Next time I won't buy "as new" because it's not.

Gauge was low. Did some tests and found the oil pressure sensor to be the culprit. The multimeter reading fluctuated. Bought and tested before replacing. Ideal reading 240 ohms. Thread sealant used in place of Phelon tape as the unit must be grounded to the unit.

Unfortunately the pressure sensor I received was dead on arrival. It needs to offer variable resistance to a variable pressure. Instead he measured the full circuit the whole time, zero resistance. I bought another one from a local dealer and it worked fine but was double the price. I'm sure it was just a strange incident.

Please check the resistance of the device to be replaced. Before buying, it is important that the characteristics of the parts match the specifications. I bought one at an auto parts store and the resistor was off, I just wasted time trying to figure it out. The pressure gauge did not show the correct oil pressure. So check out the guides.

It was used to replace a hydraulic oil gauge that someone used in an RV my wife recently bought. Because I don't like the idea of a high-pressure hot oil line feeding a gauge right a foot from my crotch while waiting for disaster while piloting a 15,000-pound brick, we decided to remove that gauge and return to the OEM. Sensor type with an electrical signal instead. It works like a charm.

These transmitters are indeed Sierra I think. They are well built and reliable. Make sure the range matches your sensor. It is also important NOT to use thread sealant. Therefore the threaded part is made of brass. All of these transmitters operate with an increasingly larger ground connection. The higher the pressure, the more the sensor grounds the sensor cable. If the base of the sensor is not firmly grounded to the engine, readings may be falsely low or erratic. esp. Do not use Teflon tape.