Here's how to tell if your Dodge pickup's oil pressure sending unit is going bad:
* Erratic or fluctuating oil pressure gauge: This is the most common symptom. The gauge needle might jump around wildly, sometimes showing normal pressure, sometimes low, or even pegged at zero, even when the engine is running smoothly. If the fluctuation is drastic and unrelated to engine load, the sending unit is a prime suspect.
* Oil pressure gauge always reads zero or very low: While this *could* indicate true low oil pressure (a serious problem!), it's also a possibility that the sending unit is simply failing to register pressure. Check the oil level first! Low oil itself can cause gauge problems, but again, low oil is a serious problem and must be addressed immediately.
* Oil pressure light stays on constantly: Similar to a consistently low reading, a constantly illuminated oil pressure light usually suggests low oil pressure—a critical issue. However, a faulty sending unit can also trigger the light.
* No change in oil pressure reading with engine RPM: Normally, oil pressure increases as engine speed increases. If the gauge remains stubbornly low or unchanged regardless of engine RPM, the sending unit is a possible culprit.
Important Considerations:
* Check your oil level: Before diagnosing a bad sending unit, always check your oil level. Low oil will affect the pressure reading, regardless of the sending unit's condition. Add oil if necessary, but *only* after the engine is completely cool.
* Mechanical oil pressure gauge: The most definitive way to rule out a true low oil pressure problem is to use a mechanical oil pressure gauge. This bypasses the electrical sending unit entirely, giving you a direct reading of the actual oil pressure. A mechanic can quickly perform this test.
* Multiple symptoms: If you have multiple issues, like erratic gauge readings, the oil pressure light staying on, and noises from the engine (which could suggest low lubrication), you have a far more serious issue than just a bad sending unit and should seek immediate professional help.
In short, erratic or inconsistent oil pressure gauge readings are the key indicator of a potentially failing oil pressure sending unit. However, always verify oil levels and consider a mechanical pressure test before replacing the sending unit to ensure you're not masking a more serious engine problem.
