What happens when oil pressure switch is leaking?

An oil pressure switch is an important component in a vehicle’s engine lubrication system. It monitors oil pressure and sends signals to activate warning lights or shut down the engine if pressure drops too low. A leak in the oil pressure switch can have serious consequences.

What is the oil pressure switch and what does it do?

The oil pressure switch, also known as the oil sending unit, is usually located near the oil filter or oil galley. It has an internal diaphragm or switch that monitors engine oil pressure. Most switches are designed to close and complete an electrical circuit when oil pressure reaches 5-10 psi. This turns on the oil pressure warning light on the dashboard to alert the driver that oil pressure is low.

The oil pressure switch serves three key functions:

• Activates low oil pressure warning light on dash – The switch turns on the warning light when pressure drops below the safe limit so the driver can take action.
• Provides oil pressure data to gauge on dash – On vehicles with an oil pressure gauge, the switch sends signals to operate the gauge.
• Shut off engine during low pressure – Some switches are designed to ground the ignition coil and shut off the engine if very low or no oil pressure is detected to prevent engine damage.

What are the symptoms of a faulty oil pressure switch?

Some common signs your oil pressure switch may be faulty or leaking include:

• Oil pressure warning light stays on – If the light remains lit even when the engine oil level is full, the switch may be malfunctioning.
• Fluctuating oil pressure gauge readings – The gauge may register abnormal spikes or drops in pressure if the switch is not reading accurately.
• Low engine oil level without leaks – An internal leak in the switch can drain engine oil without any visible external leaks.
• Difficulty starting engine – Lack of accurate oil pressure signals from a faulty switch can cause startup problems.
• Engine oil on starter or underside of car – A significant external leak could drip oil onto the starter or underside of the vehicle.

What happens when an oil pressure switch leaks externally?

If the oil pressure switch develops an external leak, it will drip engine oil in areas around the switch housing. Here’s what to watch out for with an external oil pressure switch leak:

• Oil drips underneath car – The most obvious sign is oil drips or puddles under where the switch is mounted on the engine.
• Oil leaks around starter – Starter motors are often located directly below or near the switch. Oil can drip down onto the starter.
• Oil burning smell – Oil drops leaking onto hot exhaust components can burn and create a noticeable smell.
• Low engine oil level – Enough external leakage will continually drain oil from the system and lower the amount showing on the dipstick.
• Oil leaks clogging areas – Built up drips around the switch area can create mess that needs cleaning.

An external leak is typically caused by a bad seal or gasket on the switch. But it also could indicate a problem with the switch’s housing if it is cracked or damaged. Prolonged external leaks left unchecked can lead to oil depletion and engine damage over time.

What are the effects of an internal oil pressure switch leak?

A leak inside the oil pressure switch can also drain engine oil, but often without any visible dripping. Here’s what can happen with an internal switch leak:

• No visible oil leak – Since the leak is internal, there may be no evidence of an external drip or puddle.
• Oil consumption goes up – Oil level decreases as it leaks internally but consumption may not seem abnormally high.
• Lower oil level readings – Check oil level routinely to spot any unexplained loss of oil in between oil changes.
• Oil starvation risk – If the internal leak is large, the switch can drain enough oil to starve the engine of adequate lubrication.
• Sludge buildup – Oil leaks inside the switch can also lead to sludge that prevents the diaphragm from moving properly.

These internal oil pressure switch leaks occur when the internal diaphragm ruptures. As oil passes through the switch, a tear in the diaphragm will drain oil back to the engine pan. Eventually this will lead to oil loss and pressure monitoring issues if not fixed.

Can you drive with a bad oil pressure switch?

It’s not recommended to continue driving once you suspect problems with the oil pressure switch. Here are the key risks:

• Engine damage – Driving with oil leaks can quickly lead to engine parts seizing or wear in bearings without proper lubrication.
• Oil starvation – Continued driving drains oil from the system that can’t be replenished fast enough to prevent damage.
• Sudden breakdown – Significant internal or external leaks can drain oil quickly leading to a breakdown by the roadside.
• No oil pressure warning – Driving without a working switch gives no warning of low oil pressure before severe damage occurs.
• Engine overheating – Low oil and oil leaks reduce the cooling capabilities of engine oil which can lead to overheating.

The best advice is to have your vehicle towed or repaired soon after any oil pressure switch problems are discovered. Technicians can then diagnose the source, check for engine damage, and replace the switch if faulty.

How much does it cost to replace an oil pressure switch?

The typical cost for an oil pressure switch replacement ranges from $80-$150 for parts and labor. Here are some considerations that affect the cost:

• Switch location – More difficult to reach switches take longer to replace which adds to labor time.
• Engine type – Luxury vehicles or trucks often have a higher cost for parts and labor rates.
• Shop fees – Dealerships or auto shops in high-rent urban areas charge higher hourly rates.
• Additional repairs – Other unrelated repairs done at the same time can increase the total bill.
• Brand and quality – OE switches from vehicle manufacturers tend to cost more than aftermarket brands.

While do-it-yourself replacement may be tempting, most mechanics recommend leaving it to qualified technicians. Proper diagnosis of why the switch failed and ensuring correct installation is key to prevent recurrence.

How do mechanics test a bad oil pressure switch?

Experienced mechanics use a variety of methods to diagnose issues with the oil pressure switch and confirm when replacement is required. Common oil pressure switch tests include:

• Checking dash warning lights – Warning lights that behave erratically or remain on point to switch problems.
• Using an external gauge – They temporarily connect a manual gauge to the system to compare readings vs. switch signals.
• Oil pressure tests – They check actual system pressure with specialized tools to confirm switch accuracy.
• Voltage tests – Switch electrical signals are checked with a multimeter for any voltage drops or anomalies.
• Apply controlled pressure – Pressure is applied via tools and switch contacts are tested to see if signals change as expected.
• Check switch seals & housing – Visual inspection identifies any damaged seals or housing cracks that could cause leaks.

These tests along with an analysis of oil loss symptoms help pinpoint when the switch needs to be replaced. Proper testing also identifies any underlying causes, like insufficient oil pressure, that may damage a new switch if uncorrected.

Can I drive with the oil pressure light on?

It’s never recommended to continue driving with the oil pressure warning light illuminated. The consequences can be very detrimental to your engine. Here’s why you should stop driving right away with the light on:

• Loss of oil pressure – The light indicates pressure has already fallen below the safe limit of 5-10 psi in most vehicles.
• Insufficient lubrication – Major engine components are not receiving adequate oil flow which can quickly lead to overheating or seizures.
• Bearing wear – Spinning crankshaft and connecting rod bearings require a thin oil film or they rapidly wear down.
• Data ignored – Driving with the warning light on means critical data about oil pressure is being disregarded.
• Immediate engine damage – Significant damage to bearings or other components can occur very rapidly with no oil pressure.

The bottom line is the oil pressure warning light is the last line of defense before catastrophic engine failure. It should never be ignored. Safely pull over and turn off the engine as soon as possible once it comes on and call for a tow if needed.

How do I check oil pressure without a gauge?

On vehicles without an oil pressure gauge, there are a couple simple tests to check oil pressure when problems are suspected:

• Use an external gauge – Clip on manual gauges that read pressure directly from the oil sending unit fitting.
• Oil pressure test kits – Pumps attach to the engine and reveal actual system pressure readings.
• Warning light checks – Turning on ignition without starting engine should illuminate light for bulb test.
• Listen for pump noise – Place a mechanics stethoscope against the oil pan to listen for pump operation.
• Check under valve covers – Remove covers to manually check oil squirting from pump to bearings.

While not precise measurements, these checks can identify red flags like no pump noise, weak spurts from the pump, or failure to build any pressure. This points to issues needing further diagnosis to pinpoint the exact cause and solution.

Can you repair a bad oil pressure switch?

Minor oil pressure switch leaks or problems can sometimes be repaired, but replacement is usually the best option. Here’s when switch repair may be effective:

• Loose wiring connection – Electrical problems in the connector can potentially be fixed.
• Return spring defects – Sticking contact pins due to a bad return spring might be repairable.
• Adjustment of contact – Carefully adjusting the contact point gap could resolve random signal issues.
• Debris removal – Carefully cleaning out sludge buildup inside the switch may enable normal operation.

However, internal leaks, cracked housings, major seal leaks, or blunt force damage usually require a new pressure switch. Repairs often won’t last long or fully resolve these issues. Replacement also ensures you get optimal accuracy from the sensor.

Is it safe to drive with low oil pressure?

Driving any significant distance with low oil pressure is extremely unsafe and risks major engine damage. Here are the key dangers:

• Loss of lubrication – Major components rely on oil pressure for cooling and friction reduction.
• Bearing wear – Spinning bearings without enough oil film quickly overheat and deteriorate.
• Metal on metal contact – Pistons, rings and sleeves scrape without sufficient oil causing scuffing.
• Engine seizures – Moving parts can weld together from friction heat without oil.
• Cylinder scouring – Unlubricated piston skirts scrape cylinder walls leading to scarring.

The bottom line is driving more than very short distances with low oil pressure risks destroying internal engine components. Repairs often involve a full engine rebuild or replacement. Tow your vehicle or stop driving as soon as low pressure symptoms appear.

Conclusion

An oil pressure switch leak can lead to a range of problems from inconvenient oil drips to major engine damage if left unchecked. Stay alert for symptoms like the warning light, low readings, oil loss, or leaks. Discontinue driving and have your vehicle repaired promptly when switch issues are suspected. Replacement is usually required to restore accurate oil pressure monitoring and prevent engine wear from inadequate lubrication.