1991 Ford Explorer XLT lower engine knock?

1991 Ford Explorer XLT lower engine knock? - 1

I've got a 1991 Ford Explorer XLT that seems to have some sort of lower engine knock. Still runs and drives great just driving me crazy not knowing where this sound is coming from. Almost to the tune of an oil lifter but a slight heavier/deeper? Any feedback is appreciated.

A lifter is more of a tapping noise. How many miles is on it? It could be piston slap. It could also be a crankshaft thrust bearing. I doubt it's a rod or main bearing knock because it wouldn't keep going.

It can be just detonation from bad or old gas. Also carbon build up on the pistons or out of timing can cause it. I've had all four. Sounds about the same as a rod knocking.

Spun rod bearing. Go grab yourself a junkyard engine for $150