Truck dying and oil pressure dropping to 0

ANSWER : The fuel pump will not stay on if you loose oil pressure. This is why it is shutting off. The loss of oil pressure may be from bad crankshaft bearings or camshaft bearings. The engine oil pan should be removed and the oil pump needs to be checked to ensure that you put in the pick up tube seal to the pump and connected the pump to the block. Then remove at least one main bearing cap and inspect the bearings for excessive wear and crankshaft damage. If you need some help with this, consider YourMechanic, as a certified technician can help diagnose the issue with your oil pressure firsthand and help you fix it accordingly.

ANSWER : Your vehicle has a fair amount of miles on it, but the pressure reading should still come up when you are driving. With a new pressure sending unit and a new oil pump, there must be a blockage inside the engine or there may be a disturbed bearing that isn’t allowing oil to flow properly. Consider hiring a technician to check the actual mechanical oil pressure at the sending unit port and again at the oil filter. The same technician can check the knock sensors to see if the sensors are faulty or if they are going crazy because of an internal engine concern. Consult your nearest machine shop or engine repair facility.

ANSWER : Hello – assuming an adequate oil level, which you have checked, there may be a real oil pressure problem. It’s worth checking with a know working oil pressure gauge, so that you can get the real readings (i.e. 40 psi at running RPM, 10 psi at idle – both hot – would be acceptable). It’s expected that your oil pressure will drop at a hot idle, as long as you have good pressure above idle. Low hot pressures all around are indications of excessive connecting rod or crankshaft main bearings, camshaft bearings, or oil flow bleeding off elsewhere in the engine. For professional assistance, I recommend a low oil pressure inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.

ANSWER : If you have replaced the sensor three times and it did not fix the problem, then you may have problems with the oil pressure being low at idle due to wear in the engine bearings. The reason it would be fine sometimes and not others may be due to engine load and temperature changes. Have the oil pressure tested at the sensor port to see if it is low and needs engine repairs.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to perform an inspection to determine why the Oil Pressure Light is on.

ANSWER : Your motor (454/7.4L Big Block Chevy) should have an oil pressure sending unit that is typically mounted just above the oil filter housing. This is a relatively small unit (about the diameter or a quarter or slightly bigger) with threads going into the engine block and a line coming out of the other side of the unit. Your oil pressure fluctuation sounds like this may be a case of a failing sending unit. If you are not able to replace this on your own, feel free to schedule an appointment with one of our expert mechanics here at YourMechanic to come to your location to replace your oil pressure sending unit.

ANSWER : Hi there. Typically when the oil pressure changes based on the type of oil you are using, it’s an issue with the pick-up itself. Quite often, the wrong sized or style of oil pump or a pick-up line that is too short / long, can cause inconsistent oil pressure. It’s also possible as you indicated that the oil pickup screen is clogged with sludge or debris (especially if the engine has not been rebuilt). It might be a good idea to have a professional mobile mechanic complete an oil pressure light inspection to help you pinpoint the source of the issue and recommend the right repairs.

ANSWER : Oil pressure reporting systems with programmable audible alarms are readily available. An example is the CruzPro Digital Gauge but there are many other vendors and you really have to do a product comparison and look at all the reviews. Once you select an audible alarm based system, if you desire a professional installation, you can use YourMechanic’s oil pressure sending unit service page to request installation. Of note, most damage to engines related to oil starvation occurs in the few seconds after starting. Therefore, I would recommend you FIRST install a pre-pressurization system as that will give you the most bang for the buck and indeed solve what is an immediate problem in all engines. An example of this product is the Insta-Lube Engine Pre-Lube Kit. Again, though, there are many variations on this solution. I highly recommend pre-lube and the only reason all engines do not have it is such a system adds cost and complexity to motor vehicles but it solves a real problem. A certified mechanic from YourMechanic can install such a pre-lube kit as well, if you desire. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : It is possible that they put in the wrong viscosity oil. In rare instances, a defective filter will also cause low pressure. If there is too much oil, it will aerate and cause low pressure. Be sure the oil level is really not above "max". The P2187 code will appear if the oil fill cap is not tight but it will also appear due to a myriad of causes because that code only "generally" identifies a lean running condition. Consequently, numerous parts would have to be tested including the O2 sensor, gas cap seal, manifold air leaks, any vacuum leak anywhere including PCV and EVAP systems, exhaust leaks, and fuel system faults such as failing fuel pump, clogged filter and more. Since the car has relatively low mileage, you would not expect a failed oil pump, although the pressure sensor (or switch) could be bad. However, the occurrence of the oil pressure warning light is quite coincidental to the oil change, thus I would suggest bringing the car back and asking them to redo with a new filter and double check the viscosity of the new oil that they use. If the problem persists after that, you will have to test actual operating oil pressure (at idle for instance) as well as the oil pressure switch. Finally, if the oil pressure warning light comes on continuously, unless the warning circuit itself is malfunctioning, that means the oil pressure is too low to operate the engine without damaging it. Anytime the light comes on for more than literally an instant, you should shut down the car and thus an issue like this obviously has to be repaired.

If you’d like, a YourMechanic certified mechanic can come to your home or place of business to inspect the vehicle and perform an oil pressure light is on inspection to diagnose the vehicle and suggest potential repairs.