Loud Engine Rattle all of a Sudden

I have a loud engine rattle like there’s a golf ball bouncing around in the engine. So far the mechanics have no idea where the knocking is coming from. Here’s a video of the sound at idle. If you attempt to drive (or rev above 1500rpm) the sound becomes very loud and is then obviously undrivable.

It’s a 1999 Volvo V70, 2.4L, non-turbo, automatic
It has 260,000km or 162,000mi

Listen for the fuel injectors and the lifters. Under that there is a low, steady Knock. There is also a louder bang that is irregular. It sounds like I’m hitting the camera or the car but it comes from within the engine! First it’s irregular then catches up with the engine speed. Any thoughts on what those noises might be?

I was just beginning a road trip and all the fluids were checked.
Engine has appeared to be fine for years.
I pretty much only use Shell silver grade gas.
I had filled up the tank 100 km prior.
I had just changed the oil and filter 200km prior.
Symptoms appeared as I was pulling on to the highway for the first time that day.

As I accelerated on to the on ramp (with four passengers) the oil pressure light came on.
5km after that I thought I heard a low oil ticking so I pulled over to check and as I did, the engine really started knocking and whining.
Checked the oil and it was full and later I found out there was pressure. Coolant was okay too.
Turned the car on and oil pressure light never came back on.
No check engine light.
As I tried to get off the highway the knocking was so bad I could barely drive it. Probably should have left it. Got off the highway and called a tow truck.

The mechanic has drained the oil and found metal filings. He checked the timing belt and it is fine and hasn’t slipped. No idea yet where the sound is coming from.

I’m hoping to find a similar experience to help me determine (where the noise is coming from and) if I need a new engine.

You need a new engine. You drove the car down the highway with the oil pressure light on, the car then developed engine noise including ticking and now knocking, and the mechanic has now found metal in your oil. Oil level is irrelevant to the light, so the fact that the level was fine doesn’t mean anything. You said you later found that it had oil pressure, but a) you didn’t say much about that and b) finding it later doesn’t mean that you had it while the light was on. When the oil light goes on you pull over then and there and cross your fingers that it isn’t dead already.

You YouTube video didn’t show up btw.

I agree with cig above, except that I think the engine was toast before the light came on. But had you stopped, there would have been one shot in the dark that might have saved it and that is to replace the oil filter. It is possible, remotely possible that you have a defective oil filter, but it is far more likely that the engine was going to go out on you then and there wasn’t anything you could do about it.

BTW, the knock you hear is the sound of a spun bearing. The bearing was probably already worn down and it could have been worn to the point that it caused the oil pressure to drop so low. The it finally spun.

The technical term for the condition of your engine is “busticated”.

The question now is not where is the noise coming from, but how much will it cost to replace the engine. Stop spending time and money trying to determine the cause of failure.

Driving 5km with the oil light on is 4.9km too far. At the time the light came on the oil pressure in the engine was below the minimum required for adequate lubrication and engine damage started immediately, as evidenced by the metal debris in the oil.

Get prices for the installation of a rebuilt or god used engine, and be sure that includes new oil cooler lines and a radiator, as these items will be contaminated with the metal filings from your motor oil and will quickly damage your replacement engine.

So far the mechanics have no idea where the knocking is coming from

Actually if they didn’t know that noise you need new mechanics. I think they just didn’t want to be the ones to give you the bad news.