I suspect we have two issues. First the popping and rattling noises is most likely fuel related. We need to start with checking fuel pressure and go from there with that.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
As for the oil pressure dropping that is most likely a separate issue. Oil pressure will raise and fall on older engines when you raise the RPM due to speeding up the oil pump because it is connected to the crank shaft. So when the crank spins faster the oil pump spins faster and builds pressure.
The oil pressure is created no only by the pump spinning but it pushes the oil through the tight channels and in between the bearings. When you push the oil through these tight spots the PSI goes up. As the engine wears these channels and bearings begin to "open up" and the pump is not able to build as much pressure and it begins to fluctuate more because there is less resistance.
The other possible cause is the oil pump is failing and the gears inside cannot build the pressure. Here is a guide that will help with this. The fact that we have a gauge saying it is low, we should hook a mechanical gauge to the engine just to confirm the gauge is accurate.
https://www.2carpros.com/articles/high-or-low-engine-oil-pressure
Let me know about this and we can go from there. Thanks
May 21, 2020 at 9:22 AM
