Badwolfe

I have a 1998 Supercab OFFROAD 4X4 with a 4.6L Romeo V8, while traveling on the interstate the oil pressure gauge bottomed out, raised, and bottomed again. then there was a quick grinding and it shutdown. will start, but suddenly there was only three quarts oil left and none on the engine, chassis, ground, or exhaust. My question is what repairs I'm looking at? Engine replacement, top end rebuild, or simply an oil pump?

JCR 56

Just a guess, but probably an engine.

mk99

Not sure how much oil 4.6L holds but what you describe sounds like oil pump cavitating, sucking air. Usually when that happens bearings go first.

Badwolfe

My truck has the oil filter relocated behind the bumper and a oil cooler so it holds a little over 6 quarts. I checked and there's no metal in the oil.

GMW468

I don't know if this was an option in 1998 but some vehicles have a low oil pressure shut off. Basically the engine is shut down when low oil pressure is detected in an attempt to save the engine from severe damage. But I'm not sure if a 98 would have this option.

If your oil pump took a crap, then your rods and mains are probably shot and you're looking at either a new motor or a total rebuild. Honestly, I would NEVER just replace an oil pump, I'd want to see those bearings to determine their condition before buttoning up the bottom end.

I would start by topping off my oil and then hooking up a cheap mechanical oil pressure sensor to determine if you have oil pressure or not, if there is good strong oil pressure, you might be lucky enough to just have to replace the OE sending unit. If you have low or no oil pressure, it's time to start shopping crate motors.